rgndwm manual april, 2003 final

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NRSA/HD/RGNDWM/TR:02:2003 For Official Use Only

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FOR PREPARATION OF GROUND WATER PROSPECTS MAPS Rajiv Gandhi National Drinking Water Mission Project

(Phase-II)

Sponsored by Dept. of Drinking Water Supply Ministry of Rural Development

Govt. of India

NATIONAL REMOTE SENSING AGENCY (DEPT. OF SPACE, GOVT. OF INDIA)

BALANAGAR, HYDERABAD-37

April, 2003

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This is an official document. No part of it should be reproduced in any manner without due acknowledgement.

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METHODOLOGY FOR PREPRATION OF GROUND WATER PROSPECTS MPS

Rajiv Gandhi National Drinking Water Mission Project (PHASE-II)

Dr. P.R. Reddy Dr. K. Chandra Mouly S.K. Srivastava K. Seshadri G. Srinivasa Reddy Manoj Dangwal I.C. Das

NATIONAL REMOTE SENSING AGENCY (DEPT. OF SPACE, GOVT. OF INDIA)

BALANAGAR, HYDERABAD-37

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PROJECT MANAGEMENT

Dr. D.P. Rao Director, NRSA (till, April, 2001) Overall guidance & supervision Dr. R.R. Navalgund Director, NRSA (since, May, 2001) “ “ Shri S.K. Bhan Dy. Dir. (Appls.) till June, 2002 “ “ Dr. A. Bhattacharya Dy. Dir. (RS & GIS) since, July, 2002 “ “ Dr. V. S. Hegde Dy. Dir. (Appls.) ISRO/DOS Hqrs. Adviser Dr. P.R. Reddy Project Director … … Project coordination & execution Dr. Chandra Mouly Project Manger (Andhra Pradesh & Himachal Pradesh States) Shri S.K. Srivastava Project Manger (M. P. & Chhattisgarh States) till June 2001 Shri K. Shesadri Project Manger (Kerala, Rajasthan & Orissa states) Shri G.S. Reddy Project Manger ( Karnataka State) Shri M. Dangwal Project Manger (Rajasthan State) till October, 2001 Shri I.C. Das Project Manger (M.P., Chhattisgarh & Jharkhand States) Shri M.V. Kama Raju Project Coordinator (Orissa State ) since Feb. 2003 Shri V. K. Jha Project Coordinator (Himachal Pradesh State ) since, Feb. 2003 Shri V. Tamilarasan Project Coordinator (Gujarat State ) since, Feb. 2003 Dr. S. K. Subramanian Project Coordinator (Jharkhand State ) since, Feb. 2003

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The following scientists / experts participated in the discussions and offered their suggestions in finalising the technical guidelines for preparation of ground water prospects map.

1. Shri N. Kittu Officer on Special Duty

Rajiv Gandhi National Drinking Water Mission Ministry of Rural Areas & Employment

2. Dr. P. Babu Rao Director Ground Water Department, Hyderabad

3. Dr. S.V.B.K. Bhagwan Director APSRAC, Hyderabad

4. Dr. G.V.A. Rama Krishna Scientist APSRAC, Hyderabad

5. Dr. M. Bassappa Reddy Director Dept. of Mines & Geology, Bangalore

6. Dr. Y. Lingaraju Director KSRSAC, Bangalore

7. Shri V. Gopalappa Geologist PHED, Bangalore

8. Shri P. Radhakrishnan Nair Director Kerala State Remote Sensing & Environment Centre, Trivendrum

9. Shri M. Subramanian Suptd. Engineer State Ground Water Dept., Trivendrum

10. Shri A. Jaju Jacobs Executive Engineer Kerala water Authority, Trivendrum

11. Shri S.B. Tiwari Senior Hydrogeologist PHED, Bhopal

12. Shri R.S. Bharadwaj Scientist RSAC, MPCST, Bhopal

13. Shri K.K. Sharma Senior Hydrogeologist PHED, Jaipur

14. Dr. Ashok Gahlot Research Officer

State Centre, Dept. of Science & Technology Jodhpur

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15. Shri S. Adiga Director

NNRMS-RRSSC, ISRO Hqrs., Bangalore

16. Shri V.S. Hegde Dy. Director (Applications) EOS, ISRO Hqrs., Bangalore

17. Shri K. Ganesh Raj Scientist NNRMS, ISRO Hqrs., Bangalore

18. Shri V. Tamilarasan Scientist SAC, Ahmedabad

19 Shri Arun Sharma Scientist SAC, Ahmedabad

20. Shri Uday Raj Scientist RRSSC, Bangalore

21. Dr. A. Jeyram Scientist RRSSC, Nagpur

22. Shri M. Suryanarayana Head, Geophysics Division NRSA, Hyderabad

23. Prof. V.K. Jha Head, Geology Division IIRS, Dehra Dun

24. Dr. A. Perumal Head, Integrated Surveys Division NRSA, Hyderabad

25. Dr. S.K. Subramanian Scientist, Integrated Surveys Division NRSA, Hyderabad

26. Shri M.V.V. Kamaraju Scientist, Geophysics Division NRSA, Hyderabad

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LITERATURE CONSULTED

1. Bhan, S.K. and Bedi, N. (1978). Satellite remote sensing survey of natural resources

of Andhra Pradesh. Project Report, NRSA, Hyderabad. 2. Bhan, S.K., Bhattacharya, A., Guha, P.K. and Ravindran, K.V. (1991). IRS-1A

applications in geology and mineral resources. Current Science, Vol. 61, Nos. 3 & 4, pp 247-251.

3. Department of Space / ISRO (1988). Manual for Hydrogeomorphological mapping

for Drinking Water Mission. 4. Fairbridge, R.W. (1968). The Encyclopaedia of Geomorphology. Reinhold Book

Corporation, New York. 5. Fetter, C.W. (1990). Applied Hydrogeology. CBS Publishers, Delhi. 6. Gold, D.P. (1980). Remote sensing in geology – Chapter 14 (Edited by Barry et al.).

John Wiley & Sons, New York. 7. NRSA (1995). Integrated Mission for Sustainable Development – Technical

Guidelines. National Remote Sensing Agency, Dept. of Space, Hyderabad. 8. NRSA and RRSSC (1997). Manual of procedure for preparation of wastelands digital

data base using remote sensing & GIS techniques. NRSA and RRSSC, Dept. of Space, Govt. of India.

9. Rao, D.P. et al. (1974). Integrated resources survey – a pilot project in parts of

Karimnagar district, A.P. Internal Report of Indian Photointerpretation Institute (IPI), Dehra Dun.

10. Rao, D.P., Bhattacharya, A. and Reddy, P.R. (1996). Use of IRS-1C data for

geological and geomorphological studies. Current Science, Vol. 70, N0. 7, pp 619-623.

11. Reddy, P.R. (1991). New concepts and approach for ground water evaluation and

modelling with special reference to remote sensing. Ph.D. Thesis, Osmania University, Hyderabad, India (Unpublished).

12. Reddy, P.R., Kumar, K.V. and Seshadri, K. (1996). Use of IRS-1C data in ground

water studies. Current Science, Vol. 70, N0. 7, pp 600-605.

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13. Reddy, P.R. (1999). Remote sensing in ground water studies. In : Remote Sensing for Earth Resources – Chapter 12, Publication of Association of Exploration Geophysicists, Hyderabad.

14. Reeves, R.G., Anson,A. and Landen, D. (1975). Manual of Remote Sensing, Vol.-II,

American Society of Photogrammetry, Falls Church, Virginia, USA. 15. Sabins, F.F. (1997). Remote sensing principles and interpretation. W.H. Freeman &

Company, New York. 16. SAC (1997). National (Natural) Resources Information System (NRIS) – Node

Design and Standards. SAC Document No. SAC/RSA/NRIS-SIP/SD-01/97. 17. Thornbury, W.D. (1984). Principles of Geomorphology. Wiley Eastern Limited, New

Delhi. 18. Whitten, D.G.A. and Brooks, J.R.V. (1983). A Dictionary of Geology. Penguin Books

Ltd., England.

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CONTENTS

1. 2. 3. 4. 5. 6. 7.

List of Tables, Figures and Plates List of Annexures INTRODUCTION BACKGROUND OBJECTIVES REMOTE SENSING IN GROUND WATER STUDIES DATA REQUIREMENTS AND COLLECTION GROUND WATER PROSPECTS MAPPING- THE CONCEPT AND BROAD METHODOLOGY 6.1 Factors Controlling Ground Water Regime 6.2 Classification Systems 6.2.1 Lithology 6.2.2 Geological Structures 6.2.3 Geomorphology 6.2.4 Hydrological Information and Recharge Conditions METHODOLOGY FOR PREPARING GROUND WATER PROSPECTS MAP 7.1 Preparation of Base Map 7.2 Preparation of Lithological Map Overlay 7.3 Preparation of Structural Map Overlay

7.4 Preparation of Geomorphic Map Overlay

7.5 Preparation of Hydrological Map Overlay

7.6 Field Visit And Data Collection

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7.6.1 Planning 7.6.2 Verification of Lithological, Structural, Geomorphological and Hydrological Maps 7.6.3 Collection of Ground Water Information

7.6.4 Information about Problem Habitations 7.7 Corrections / Modifications in the Lithological, Structural, Geomorphological, Hydrological and Base Maps 7.8 Preparation Of Ground Water Prospects Map 7.8.1 Draft map preparation

7.8.2 Digitisation 7.8.3 Generation of final ground water prospects map 7.8.4 Ground water prospects evaluation 7.8.5 Colour scheme

7.9 Quality Check 7.10 Output Generation

7.10.1 Option-I 7.10.2 Option-II

SCOPE OF GROUND WATER PROSPECTS MAPS ANNEXURES - I to X

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LIST OF TABLES, FIGURES AND PLATES

Tables

Table-1 Table-2 Table-3

Classification of rock types / lithologic units. Classification of geological structures. Classification of geomorphic units / landforms.

Figure Figure-1

Flow chart depicting the methodology for preparation of ground water prospects map.

Plate

Plate-1

Ground water prospects map for parts of Tumkur district, Karnataka (part of toposheet no. 57 G/3).

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LIST OF ANNEXURES

Annexure-I Symbols for representing base map information Annexure-II Symbols for representing structural information Annexure-III Symbols for representing hydrological information Annexure-IV Colour scheme for representing ground water prospects information Annexure-V Proforma for collecting lithologic / structural / geomorphic /

hydrological information

Annexure-VI Proforma for collecting well inventory data Annexure-VIIA Description of geological units Annexure-VIIB Description of geomorphic units Annexure-VIII Additional geomorphic units, methodology for Deccan Traps & sample

legend, Guidelines for suggesting recharge structures Annexure-IX Phase-II -- Improvements / Modifications in the methodology Annexure-X Quality check proforma

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1. INTRODUCTION

The Rajiv Gandhi National Drinking Water Mission (RGNDWM), Ministry of Rural

Areas and Employment, Govt. of India has approached the Dept. of Space / NRSA for taking up a project for preparation of ground water prospects maps on the scale of 1:50,000, using high resolution satellite data towards scientific source finding of drinking water for all the non-covered (NC) and partially-covered (PC) habitations in the country by the concerned States and Union Territories. The RGNDWM indicated that as on 1.4.98, nearly 4.4 lakhs NC and PC habitations existed in the country spread over in different States. Thus, more than 30% of the total habitations in the country are not having proper drinking water sources. Due to increasing population and declining ground water levels, more villages are added to PC and NC habitations every year. Taking this as a serious issue, the Govt. of India has included this in the common minimum programme for providing drinking water to all the villages in the country on priority basis in a time-bound manner.

In pursuance of the above objectives and realizing the importance of scientific

database for selection of well sites for establishing drinking water sources to all the problematic habitations in the country, the RGNDWM has requested NRSA / DOS to prepare the ground water prospects maps. In response to the above, NRSA / DOS has submitted a project proposal to the RGNDWM for taking up the total work as an integrated project including satellite data interpretation, preparation of ground water prospects maps, follow-up ground surveys, identification of sites on the ground for drilling, selection of sites for construction of water harvesting structures and ultimately creating a digital database.

After detailed discussions and deliberations, ultimately the RGNDWM has

entrusted NRSA to prepare the ground water prospects maps on 1:50,000 scale based on satellite imagery interpretation with limited field checks. Initially in Phase – I programme six (6) states namely - Rajasthan, Madhya Pradesh, Chhattisgarh, Andhra Pradesh, Karnataka and Kerala were taken up in January, 1999 and subsequently during Phase – II Jharkhand state was added in October 2001 and Himachal Pradesh, Orissa and Gujarat states in October 2002.

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2. BACKGROUND

In India, more than 90% of rural and nearly 30% of urban population depends on

ground water for meeting their drinking and domestic requirements. In addition, it accounts for nearly 60% of the irrigation potential created in the country. The distribution of ground water is not uniform in all the regions. The spatio-temporal variations in rainfall and regional / local differences in geology and geomorphology have led to an uneven distribution of ground water in different regions across the country. This uneven distribution (poor prospects) and indiscriminate tapping (over-exploitation) in certain zones are the main reasons leading to scarcity of drinking water in many parts of the country. In view of this, a large number of habitations in the country have remained as problem villages not having sustainable drinking water sources. In this context, the ground water source finding for planning sustainable drinking water schemes assumes great significance.

In many States, Public Health Engineering Departments (PHEDs) and

Panchayath Raj Engineering Departments (PREDs) are engaged in rural drinking water supply. Potable water is provided to the rural masses by these departments mainly through hand pump wells and piped water supply schemes by pumping of water from bore / tube wells and connecting to overhead tanks / ground level reservoirs. In water scarcity areas, water is also supplied to villages through tankers during summer season. These departments are having well established drilling and maintenance units supported by experienced hydrogeologists for selection of sites for drilling. However, scientific database on ground water, which facilitates identification of prospective ground water zones for systematic selection of appropriate sites for drilling is not available in majority of the cases. Added to this, these hydrogeologists do not have enough time to select the sites by conducting systematic hydrogeological studies in the area followed by site specific investigations in the favourable zones. Due to work pressure, they have to select large number of sites for drilling in a short period to tackle the drinking water problem on war footing. This has resulted in low success rate of wells. In addition, many wells have started drying up very soon due to recharge problem; thus, more and more habitations are falling into problematic category.

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3. OBJECTIVES

The main objective of this project is to generate a scientific database for ground

water on appropriate scale towards scientific source finding of ground water for all the non-covered (NC) and partially-covered (PC) habitations besides promoting systematic planning and development of ground water in the country. In addition, these maps should also provide necessary information for selection of sites for construction of recharge structures to improve the sustainability of drinking water sources, wherever required.

Towards this, it has been decided to prepare the ground water prospects

maps on 1:50,000 scale incorporating geological (lithological and structural), geomorphological and hydrological information. Such integrated information provided in the ground water prospects maps form a suitable database for narrowing down the target zones and systematic selection of sites for drilling, after conducting follow-up ground surveys to establish drinking water sources to all the non-covered and partially-covered habitations, besides providing information for selection of sites for construction of recharge structures to improve the sustainability of drinking water sources, wherever required.

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4. REMOTE SENSING IN GROUND WATER STUDIES

During the last three decades, different organisations like Geological Survey of India (GSI), Central Ground Water Board (CGWB), National Remote Sensing Agency (NRSA), Space Application Centre (SAC), Ground Water Departments of different states, Regional Remote Sensing Service Centres (RRSSCs), State Remote Sensing Centres, and Academic Institutions / Universities have used the aerial photographs and satellite imagery for mapping geology, geomorphology and for identifying potential ground water zones.

The methodology for preparing ground water maps using remote sensing data

has undergone rapid changes during the last two decades. Initially, remote sensing data was used mainly for updating and refining the hydrogeological maps prepared from ground surveys. Subsequently, many organisations in the country have started preparing the ground water maps through visual interpretation of satellite data with limited field checks. These maps, prepared by different workers with different titles, vary greatly in their quality and information content. However, these studies have undoubtedly contributed to gradual improvement in the mapping procedures. Significant studies carried out at NRSA/DOS during this period are discussed below :

Hydromorphological maps were prepared (D.P.Rao et al., 1974) through aerial

photo-interpretation on 1:50,000 scale indicating the hydromorphic unit-wise ground water potential in qualitative terms i.e. very good, good, poor, none, etc.

Geomorphological maps were prepared (S.K. Bhan and Naresh Bedi, 1978)

based on visual interpretation of Landsat-1 imagery on 1:250,000 scale and geomorphic province-wise ground water potentials were evaluated taking into account the landform, lithology, drainage and lineament density and the ground water potentials were indicated in qualitative terms as very high, high, moderate and low.

Ground water potential maps were prepared on 1:25,000 scale based on visual

interpretation of Landsat-MSS data (P.R. Reddy and R.S. Rao, 1984), wherein the ground water potentials were evaluated by combining the geology, geomorphology, terrain conditions, depth of weathering, etc. Ground water potential maps were prepared on 1:50,000 scale using high resolution Landsat-TM data (P.R. Reddy and A. Perumal, 1985; R.S. Rao, 1985), wherein the ground water prospects were evaluated taking into account the lithology, landform and structural information. Ground water potential maps were also prepared on 1:250,000 scale using Landsat-TM data(Dept.of Space 1986-87) for the states of Maharashtra, Karnataka and Rajasthan by adopting a common legend.

Hydrogeomorphological maps were prepared on 1:250,000 scale using Landsat-

TM and IRS-1A/1B data for all the 447 districts in the country(Dept.of Space with the support of other depts., 1987-92), under National Drinking Water Technology Mission. In these maps, the ground water prospects were evaluated in terms of low, moderate,

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high, etc by taking into account the lithology, geomorphology and structural information. Subsequently, hydrogeomorphological maps were also prepared on 1:50,000 scale for some selected areas under Integrated Mission for Sustainable Development (NRSA / DOS, 1995-99). In these maps also, the ground water prospects were indicated as very good, moderate, poor, etc.

During the last few years, studies conducted at NRSA and other centers of Dept.

of Space (under IMSD Project and other R&D studies)have proved the usefulness of satellite data for selection of sites for construction of recharge structures7,13,ground water resource estimation and budgeting , ground water draft estimation, mapping of ground water over-exploited zones13.

Thus, the use of satellite data has been demonstrated for ground water mapping

and selection of sites for planning recharge structures.

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5. DATA REQUIREMENTS AND COLLECTION

The data requirements and collection for preparing the ground water prospects

map are given here under : 1. Geocoded (precision scale corrected) IRS-1C/1D LISS-III FCC imagery on 1:50,000

scale, preferably of February-April period with scene specific enhancement (to be provided by NRSA ),

2. Locations of the non-covered (NC) and partially-covered (PC) habitations (to be

provided by the concerned Depts of the respective States), 3. Survey of India (SOI) toposheets on 1:50,000 scale for consultation (to be procured

by the investigator), 4. Existing geological, hydrogeological, geomorphological and geophysical maps and

information (to be collected by the investigator), 5. Historic data of the observation wells available with the concerned State Depts. and

CGWB (to be collected by the investigator), and 6. Ground hydrogeological and well observation data for 80 – 100 wells in each map

(to be collected by the investigator during field surveys).

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6. GROUND WATER PROSPECTS MAPPING- THE CONCEPT AND BROAD METHODOLOGY

The conventional hydrogeological maps prepared mainly based on ground

hydrogeological surveys provide geological unit-wise ground water prospects. However, within each geological unit (rock type), the ground water conditions vary significantly depending upon the relief, slope, depth of weathering, nature of the weathered material, presence of fractures, surface water bodies, canals, irrigated fields, etc. Therefore, a different but systematic approach / methodology, which can take care of large amount of variability within a geologic unit, is required to understand the ground water prospects more clearly. Such a methodology was developed (P.R. Reddy, 1991) defining the total ground water regime as a combination of 4 factors, i.e. 1) Lithology, 2) Landform, 3) Structure and 4) recharge conditions. Systematic and well defined classification systems were evolved for each of these factors and an innovative approach was developed for preparing the ground water prospective zone maps representing lithology with code numbers, landforms with alphabetic annotation, geological structures with line symbols, hydrological data with colours / symbols and ground water prospects with different colours following the VIBGYOR colour scheme. Thus, by integrating the lithological, landform, structural and hydrological data sets, supported by correlation models, the quantitative information on ground water prospects could be provided indicating the nature of aquifer, type of aquifer, type of wells suitable, their depth range, yield range, success rate, sustainability, etc.

These ground water prospects maps form a very good database and help the

geologists of user departments in identifying favourable zones (prospective zones) around the problem villages, thereby narrowing down the target areas. Then, by conducting detailed ground hydrogeological and geophysical surveys within these zones, most appropriate sites can be selected for drilling. Further, these maps will also be useful for identifying suitable zones/sites for planning recharge structures to improve the sustainability of drinking water sources. Thus, the ground water prospects maps will serve the twin benefit of helping the field geologists to - 1) quickly identify the prospective ground water zones for conducting site specific investigations, and 2) select the sites for planning recharge structures to improve sustainability of drinking water sources, wherever required. The factors controlling the ground water regime, their classification systems and the methodology for preparing ground water prospects maps are described here under (Chapters 6 & 7). Most of this is adopted from P.R. Reddy, 1991 with minor modifications.

6.1 FACTORS CONTROLLING GROUND WATER REGIME

The ground water regime is a dynamic system wherein water is absorbed at the surface of the earth and eventually recycled back to the surface through the geological strata. In this process, various elements like relief, slope, ruggedness, depth and nature of weathering, thickness and nature of deposited material, distribution of surface water bodies, river / stream network, precipitation, canal command areas, ground water irrigated areas, etc also influence the ground water regime, besides the geologic framework. Thus, the framework in which the ground water occurs is as varied as that of

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rock types, as intricate as their structural deformation and geomorphic history, and as complex as that of the balance among the lithologic, structural, geomorphic and hydrologic parameters. The possible combinations of variety and intricacy are virtually infinite leading to the unavoidable conclusion that the ground water conditions at a given site are unique and not completely amenable to scientific understanding. Some of the conditions are often obscured and not readily apparent even from the field observations. However, factor-wise analysis, systematic mapping, data integration and interpretation based on conceptual understanding will help in overcoming this problem to some extent11.

Though, there are a large number of variables that are important in understanding the ground water conditions of an area, it is not possible to separately map and study all the variables individually during the course of the investigation. Rarely it is possible for an investigator to complete all the examinations to eliminate uncertainties and provide quantitative information about the type, thickness and depth of aquifer, its yield potential, success rate, etc with complete confidence. Varying degrees of uncertainty and inconsistency are inherent in the present methodology (conventional hydrogeological mapping). Hence, the entire procedure of mapping has to be made more systematic and simpler with well defined units based on which better inferences can be made. For this purpose, all the variables that control the ground water regime have been grouped into the following 4 factors - 1. Geology / Lithology 2. Geological Structures 3. Geomorphology / Landforms 4. Recharge conditions.

Once, information on these 4 factors is precisely known, it is possible to

understand the ground water regime better by visualising the gross aquifer characteristics of each unit11. Systematic visual interpretation of satellite imagery in conjunction with existing geological / hydrogeological / geomorphological maps and data supported by limited field checks / observations provide the information related to these 4 factors. By integrating the lithological, structural, landform and hydrological information referred above, the ground water prospects map can be prepared which provide better understanding of ground water regime as compared to the conventional hydrogeological map.

6.2 CLASSIFICATION SYSTEMS

6.2.1 Lithology The geological classification of different rock types which is mainly based on their

origin and mineral composition does not provide sufficient information for hydrogeological studies. In ground water studies, texture of the rocks is more important as it defines the water holding and transmitting capacity of the rocks vis-a-vis the aquifer characteristics. Considering this, a separate lithologic classification system has been evolved, wherein all the rocks having similar or matching hydrogeological characteristics are grouped together. Thus, mainly based on the texture of the rocks (primary / secondary porosity and permeability resulting from inter-granular pore spaces, bedding,

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cleavage, schistosity, foliation, etc), a two stage lithological classification system has been evolved11 and presented in Table-1.

In this classification, all the rock types have been classified into 9 rock groups.

Under each group, several lithologic units that are likely to occur have been identified. For the sake of easy representation on the maps, numerical code numbers have been assigned to different rock groups and rock types / lithologic units. In the numerical code number of the rock type / lithologic unit, the first digit represents the rock group and the second digit represents the lithologic unit. In a given area, if more than one similar lithologic unit occurs at different stratigraphic positions, a third digit has to be added to the code number for further differentiation as explained in section 7.2 in more detail. Efforts have been made to include all possible variations in lithologic units in each rock group. Further, provision has also been kept to include additional units, wherever required. However, this should be done judiciously after fully satisfying that such variations are not covered in the existing litho-units and creating an additional unit is absolutely essential. This should be done in consultation with the Project Director, Rajiv Gandhi National Drinking Water Mission, NRSA. 6.2.2 Geological Structures In the hard rock areas, geological structures exercise definite control on the aquifer characteristics of different rock types, as the structurally weak planes act as conduits for movement and occurrence of ground water, thereby introducing an element of directional variation in hydraulic conductivity11. The geological structures that can be identified on satellite imagery can be divided into two categories: (i) primary structures- associated with specific rock types and (ii) secondary structures- which cut, deform and otherwise affect the rock units themselves13. Both these primary and secondary geological structures have been classified into the following 8 categories to facilitate systematic mapping based on satellite imagery interpretation with limited field checks (Table-2). All these structures like - i) bedding, ii) schistosity / foliation, iii) faults, iv) fractures / lineaments, v) fractures / lineaments (inferred), vi) shear zones, vii) folds and viii) trend lines have to be represented on the map with different line symbols as indicated in Annexure-II. 6.2.3 Geomorphology

The earth’s surface can be classified into different geomorphic units / landforms based on their physiographic expression, origin, material content and climatic conditions, etc. Different types of geomorphological maps can be prepared giving emphasis to some of these factors. Hence, the geomorphological maps vary greatly depending on the purpose for which they are prepared, i.e. terrain evaluation, land resource mapping, soil classification, watershed prioritisation, ground water studies, etc. A number of terms are available in the geomorphic literature for describing a variety of landforms, but all of them may not exercise definite control on the ground water regime. In view of this, a systematic classification of geomorphic units / landforms wherein the individual geomorphic unit / landform has definite bearing on the ground water regime11, has become necessary to follow in this project.

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Considering this, a geomorphic classification system has been developed11 for preparing the ground water prospects map on 1:50,000 scale. The same has been pesented in Table-3. In this classification all the geomorphic units / landforms have been broadly classified into 3 major zones, (1) Hills & Plateaus, (2) Piedmont Zones and (3) Plains. In each of these zones, a number of geomorphic units / landforms which are possible to occur have been included as shown in Table-3. The details provided in this classification are commensurate with the scale of mapping, i.e. 1:50,000 scale. However, depending on the ground realities, additional landforms, if any, can also be included. Further, it may be mentioned here that much of the geomorphic terminology used in this classification system have been taken from the existing geomorphic literature. But, these terms are used more liberally to cover additional landforms which were not originally intended for. Thus, the names of landforms given in this classification system are not used in their strict sense. Their usage has been extended to cover a variety of landforms. For example, the terms pediment and pediplain were originally used to represent rock-cut surfaces / plains formed mainly by massive rocks in arid and semi-arid climatic zones; whereas, these terms are used here to represent all gently undulating plains formed on all rock formations (including sedimentary and volcanic rocks) in all climatic zones. 6.2.4 Hydrological Information and Recharge Conditions Recharge is the most important factor in ground water studies. If sufficient recharge is not there, the most favourable aquifer zones will also go dry. Hence, it is essential to pay sufficient attention to study the recharge conditions before evaluating the ground water prospects of each unit. As already mentioned earlier at section 6.1.4, the hydrological information derived from satellite imagery in conjunction with ground hydrological data will be quite useful in proper evaluation of recharge conditions. The recharge conditions can be given as excellent, very good, good, moderate, limited, poor and nil considering the perennial / ephemeral nature of water bodies, rivers, streams and canals, amount of rainfall, the extent of recharging area and the hydrogeological conditions. In the ground water prospects map, the recharge conditions also have to be given in the legend for each hydrogeomorphic unit along with rock type and landform. This not only helps in proper evaluation of ground water prospects but is also useful for selection of sites for planning recharge structures in different units to improve the sustainability of drinking water sources11.

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TABLE-1 classification of rock types / lithologic units. (P.R. Reddy, 1991 with minor modifications)

Code Rock Group Code Rock Type / Lithologic Unit

No. No. 1 UNCONSOLIDATED

SEDIMENTS 11 12 13 14 15 16 17 18 19

Alluvium – sand / silt dominant Alluvium – clay dominant Alluvium – sand / silt & clay alternating beds Colluvium – clay / silt dominant Colluvium – pebble / cobble dominant Eolian Sand / silt Loess ---------- ----------

2 RESIDUAL CAPPINGS 21 22 23 24 25 26 27

Laterite (ferricrete) Bauxite (alecrete) Kankar (Calcrete) Chert (silcrete) Detrital laterite / bauxite --------- ---------

3 DECCAN TRAPS & INTERTRAPPEANS

31 32 33 34 35 36 37 38 39

Inter-/infra-trappean sand / clay beds Tuffacious basalt Vesicular basalt Amygdaloidal basalt Massive basalt Columnar basalt Red / green bole ---------- ----------

4 OLDER VOLCANICS & METAVOLCANICS

41 42 43 44 45 46

Basalt / meta basalt Rhyolite / meta rhyolite Dacite / meta dacite Andesite / meta andesite ---------- ----------

5 SEMI-CONSOLIDATED SEDIMENTS

51 52 53 54 55 56 57 58 59

Sandstone / pebble bed / conglomerate Shaly sandstone Sandstone with shale / coal bands Sandy shale Shale with sandstone / limestone bands Shale / coal / lignite Limestone / shell limestone Limestone with shale bands ----------

Table contd.

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6 CONSOLIDATED SEDIMENTS

61 62 63 64 65 66 67 68 69

Thin bedded / flaggy sandstone / quartzite Thick bedded / massive sandstone / quartzite Thin bedded / flaggy limestone / dolomite Thick bedded / massive limestone / dolomite Shaly limestone Shale with limestone / sandstone bands / lenses Shale Conglomerate ----------

7 PLUTONIC ROCKS 71 72 73 74 75

Alkaline rocks | Name of rock Basic rocks | to be specified Ultrabasic / ultramafic rocks | ---------- ----------

8 GNEISS-GRANITOID COMPLEX / CHARNOCKITE-KHONDALITE COMPLEX / MIGMATITE

81 82 83 84 85 86 87 88

Granites / Acidic rocks Migmatite / Migmatite complex Granitoid Gneiss / Gneissic Granitoid / Granitoid complex Charnockite Khondalite Charnockite – Khondalite complex ---------- ----------

9 METAMORPHIC ROCKS 91 92 93 94 95 96 97 98 99

Gneiss Schist Phyllite Slate Quartzite Calc-gneiss / schist Marble / Crystalline limestone ---------- ----------

(Red Colour) Q _______ Q Quartz reef / Quartzite band “ “ P _______ P Pegmatite “ “ D _______ D Basic dyke Note: 1) This classification is based on texture of the rocks, mainly for hydrogeological purpose. In the map

legend, the rock types have to be listed as per the geological sequence indicating their type name like Barakar sandstone Peninsular gneiss etc. giving the appropriate code number from this table.

2) In case of unconsolidated sediments where they are shallow (less than 10 m thick), their composition

may be indicated in the remarks column of the map legend and the rock type occurring below such sediments should be indicated in the rock type / geologic sequence column.

3) In case of residual cappings, the underlying rock type should be indicated in the remarks column of

the map legend. 4) Quartz reef, pegmatite, basic dyke may also be marked as polygon features, wherever required.

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Table-2 Classification of geological structures

Structure Category

1.

Bedding

Gentle (<100 dip) Moderate (10-450 dip) Steep (45-800 dip) Sub-vertical to vertical (>800 dip)

2.

Schistosity / Foliation

Gentle (<100 dip) Moderate (10-450 dip) Steep (45-800 dip) Sub-vertical to vertical (>800 dip)

3.

Fault

Minor (< 3 km length) Major (> 3 km length)

4.

Fracture / lineament


5.

Fracture / lineament (inferred)


6.

Folds

Anticline / Antiform Syncline / Synform

7.

Shear zone

8.

Trend line

Symbols for representing the above structures are shown in Annexure-II.

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Table-3 Classification of geomorphic units / landforms.

(P.R. Reddy, 1991 with minor modifications) Physiography Geomorphic Unit / Landform Code I.

HILLS & PLATEAUS

Hills

Structural Hills Denudational Hills Residual Hills Inselberg

SH DH RH I

Plateaus Upper Plateau

- Undissected - Mod. Dissected - Highly Dissected

UP UPU UPM UPH

Middle Plateau - Undissected - Mod. Dissected - Highly Dissected

MP MPU MPM MPH

Lower Plateau - Undissected - Mod. Dissected - Highly Dissected

LP LPU LPM LPH

Other Landforms common to Hills and Plateaus Linear / Curvilinear Ridge Cuesta Mesa Butte Inselberg Outer Fringe of Plateau Fracture / Fault line Valley Intermontane Valley Valley Valley fill – Shallow Valley fill – Moderate Valley fill – Deep

LR/CR C M B I OFP FV IV V VFS VFM VFD

II. PIEDMONT ZONE

Piedmont Slope Pediment Pediment-Inselberg Complex Piedmont Alluvium

- Shallow - Moderate - Deep

PS PD PIC PA PAS PAM PAD

Bajada - Shallow - Moderate - Deep

BJ BJS BJM BJD

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Linear / Curvilinear Ridge Cuesta Mesa Butte Inselberg Alluvial Fan Talus Cone Fracture / Fault line valley Valley Valley fill – Shallow Valley fill – Moderate Valley fill – Deep

LR/CR C M B I AF TC FV V VFS VFM VFD

III. PLAINS Pediplain Weathered - Shallow - Moderate - Deep

Buried


PP PPS PPM PPD BP BPS BPM BPD

Stripped Plain Shallow Basement Moderate Basement Deep Basement

SP SPS SPM SPD

Other Landforms common to Pediplain & Stripped Plain Linear / Curvilinear Ridge Cuesta Mesa Butte Inselberg Valley fill – Shallow Valley fill – Moderate Valley fill – Deep Fracture / Fault line valley Valley

LR/CR C M B I VFS VFM VFD FV V

Flood Plain - Shallow - Moderate - Deep

FP FPS FPM FPD

Alluvial Plain

- Shallow - Moderate

- Deep

AP APS APM APD

Deltaic Plain - Shallow - Moderate

- Deep

DP DPS DPM DPD

Other Landforms common to Flood Plain, Alluvial Plain and Deltaic Plain Channel Bar Point Bar River Terrace

CB PB RT NL BS

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Natural Levee Back Swamp Cut-off Meander Abandoned Channel Ox-bow Lake Palaeochannel Buried Channel

CM AC OL PC BC

Coastal Plain - Shallow - Moderate - Deep

Beach Beach Ridge Beach Ridge & Swale Complex Swale Offshore Bar Spit Mud Flat Salt Flat Tidal Flat Lagoon Channel Island Palaeochannel Buried Channel

CP CPS CPM CPD BH BR BSC SW OB ST MF SF TF LG CI PC BC

Eolian Plain


EP EPS EPM EPD

Sand Dune Stabilised Dune Dune Complex Interdunal Depression Interdunal Flat Playa Desert Pavement Loess Plain Palaeochannel Buried Channel Escarpment

SD STD DC ID IF PL DPV LP PC BC

Note:

1. In case of Plateau, the elevation range (in metres) have to be given in the parenthesis along with the unit name [e.g. Upper Plateau – Undissected (UPU) – (400-500 m)] in the legend.

2. The Flood Plain, Alluvial Plain, Deltaic Plain and Coastal Plain may be further classified and mapped as

upper / lower, older / younger, wherever required.

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7. METHODOLOGY FOR PREPARING GROUND WATER

PROSPECTS MAP

The broad methodology to be followed for preparing the ground water prospects

map is shown in the flow chart (Figure-1). It involves the following 7 steps :

Preparation of base map from SOI toposheet, and lithological, structural, geomorphological and hydrological map overlays based on the visual interpretation of satellite image in conjunction with the existing maps / literature. Preliminary quality check and suggestions for improvement. Field visits for checking the interpretation, collecting the additional hydrogeological information. Incorporation of field observations in the lithological, structural, geomorphological, hydrological and base map overlays. Preparation of ground water prospects map by combining the lithological, structural, geomorphological and hydrological map overlays and transferring the details on to the base map, and preparation of legend indicating hydrogeomorphic unit-wise ground water prospects. Final quality check and suggestions for improvement. Incorporation of corrections / modifications suggested during the quality check. Output generation and submission to NRSA. For this purpose, there are 2 options –

OPTION-I : This option is for the organisations where the digitisation and hard copy output generation facilities are not available. Such organisations can submit the outputs (individual map overlays and ground water prospects map) in the form of cartographically drawn hard copies.

OPTION-II: This option is for the organisations where digitisation and output

generation facilities are available in-house. Such organisations can take up the digitisation, integration and map composition job and have to submit the soft and hard copies of the outputs as explained in section 7.10.2.

The detailed methodology for preparing the individual map overlays, i.e. base

map, lithological map, structural map, geomorphological map and hydrological map, their integration for preparing the ground water prospects maps are discussed in this chapter. The Quality Check (QC) will be carried out by the Quality Assurance and

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Standardisation (QAS) team of NRSA/DOS as shown in Figure-1 to ensure the high quality and uniformity in the end products.

7.1 PREPARATION OF BASE MAP

The base map has to be prepared on a transparent overlay mainly using the precission corrected Satelite Imagery on 1:50,000 scale. Field information and collateral data have to be used and toposheet may be consulted for preparing the base map. The base map should contain the following details with appropriate symbols as shown in the Annexure-I :

1. Rivers / streams (entire drainage upto first order strteams). In case of Hilly areas and highly dissected terrain where drainage density is very high, some first order streams can be omitted to reduce the clumsiness in the map).

2. All water bodies, both perennial and ephemeral have to be mapped based on the

satellite image.

3. Canals

4. National highways

5. State highways

6. Metalled and unmetalled roads connecting all the habitations

7. Railway lines

8. Cities / major towns / villages / Habitations as seen on the satellite data (Names of the habitations have to be indicated on the map by consulting the toposheet or any other map)

9. Problem villages (NC / PC habitations) with names to be indicated with different

symbols as shown in Annexure-I. The locations of NC/PC villages have to be collected from the concerned State Depts.

10. International, State, District, Taluk / Tahsil boundaries

11. Springs / seepages (Sfrom ground surveys)

7.2 PREPARATION OF LITHOLOGICAL MAP OVERLAY

The synoptic view and multispectral nature of the satellite imagery help in discrimination and mapping of different lithologic units. Geological mapping is carried out mainly based on visual interpretation of satellite images adopting deductive approach by studying image characteristics and terrain information in conjunction with a priori knowledge of general geological setting of the area. The tone (colour) and landform characteristics combined with relative erodibility, drainage, soil type, land use/ land cover and other contextual information observable on the satellite image are useful in differentiating different rock groups / types.

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The direct clue for interpretation of rock type / lithologic unit comes from the tone (colour) of the image. For example, the acidic and arenaceous rocks appear in lighter tone as compared to the basic / argillaceous rocks. Similarly, coarse grained rocks having higher porosity and permeability appear brighter on the image as compared to fine grained rocks having higher moisture retaining capacity. The highly resistant rock formations occur as different types of hills depending upon their texture and internal structure; whereas, the easily erodible rocks occur as different types of plains and valleys. While dendritic drainage indicates homogeneous rocks, the trellis, rectangular and parallel drainage patterns indicate structural and lithological controls. The coarse drainage texture indicates highly porous and permeable rock formations; whereas, fine drainage texture is more common in less pervious formations. The coarse textured and light coloured soils indicate the acidic / arenaceous rocks rich in quartz and felspars; whereas, the fine textured and dark coloured soils indicate basic / argillaceous rocks. Thus, by combining all these evidences, it is possible to interpret different rock groups / formations. Though, one or two recognition elements, mentioned above, may be diagnostic for the identification of a particular rock type, the convergence of evidences must be considered by studying all the recognition elements conjunctively. However, limited field checks are a must to identify the rock types and to make necessary corrections in the interpreted map based on field evidences. Once, the rock types are identified, the contacts can be extended over large areas with minimum ground control. The identification, correlation and extrapolation of rock types is possible based on similar spectral and morphological characters.

For preparation of lithological map overlay, information from the following sources is required : 1. Consultation of existing geological / hydrogeological maps or literature

2. Interpretation of satellite imagery

3. Field visits / surveys.

Consultation of existing maps/literature helps in knowing general geological setting of the area and different rocks types that occur or likely to occur in the area. Where previous literature is not available and differentiation of rock types is very difficult/not possible, a reconnaissance field visit will be useful. With this “ a priori knowledge,” the geologist should look at the satellite imagery and try to correlate the different image characteristics with different rock types. Where, contrasting rock types are occurring, the boundaries can be seen very clearly on the satellite imagery with different colours (tones) or landforms. In other cases, complementary evidences have to be considered to demarcate the boundaries between different rock types. This can be done more effectively by keeping the satellite imagery on light table and putting a fully transparent overlay. On this overlay all lithological boundaries should be marked. Where previous geological maps on 1:50,000 scale are available, the same may be overlaid on the satellite imagery in the form of transparent tracing and further modifications / corrections and editing should be done incorporating additional details that can be interpreted from satellite imagery. After total interpretation of the imagery, each lithologic unit / rock type should be indicated with appropriate lithologic code number like 21, 34, 76 as given in the lithologic classification system (Table-1). In this code number, the first numeral represents the rock group code and the second numeral

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represents the lithologic unit / rock type code. If similar rock type occurs at different stages of succession or if a rock is sub-divided based on mineralogic composition, it has to be indicated by adding a 3rd digit like - 541, 542, 543, in the increasing order from top to bottom. If any lithologic unit / rock type is not covered in Table-1, it may be added as provision has been made to include the extra units, if any. In case two digit codes are exhausted for a particular rock group, third digit may be added to the last code to include the extra lithologic unit / rock type, e.g. 691, 692, 693, etc. Wherever the lithological units are not clearly identifiable, they should be indicated with question marks for verification on the ground during field visit. After the field verification, final lithological map overlay has to be prepared by incorporating the field observations. 7.3 PREPARATION OF STRUCTURAL MAP OVERLAY The utility of satellite imagery for mapping the geological structures has been emphasised by various workers. The synoptic coverage provided by the satellite imagery enable mapping regional structures which is difficult in conventional ground surveys due to scanty rock exposures, soil cover, lack of continuous observations, etc. The different types of primary and secondary geological structures (attitude of beds, schistosity / foliation, folds, lineaments etc.) can be interpreted from satellite imagery by studying the landforms, slope asymmetry, outcrop pattern, drainage pattern, individual stream / river courses, etc.

Lineaments representing the faults, fractures, shear zones, etc are the most obvious structural features interpretable on the satellite imagery. They control the occurrence and movement of ground water in hard rock terrain, and their significance in ground water exploration has been proved beyond doubt. They occur in parallel sets in different directions indicating different tectonic events. They appear as linear to curvilinear lines on the satellite imagery and are often marked by the presence of moisture, alignment of vegetation, straight stream / river courses, alignment of tanks / ponds, etc. These lineaments can be further subdivided into faults, fractures and shear based on their image characters and geological evidences.

The attitude of beds (strike and dip) can be estimated broadly by studying the

slope asymmetry, landform, drainage characteristics, etc. For example, horizontal to sub-horizontal beds show mesa / butte type of landform, dendritic drainage pattern and tonal / colour banding parallel to the contour lines. Inclined beds show triangular dip facets, cuestas, homoclines and hogbacks. The schistosity / foliation of the rocks are depicted on the satellite imagery by numerous thin, wavy and discontinuous lines. Folds can be identified on the satellite imagery by mapping the marker horizons. Further classification into anticline or syncline can be made on the basis of dip direction of beds.

For preparation of structural overlay, information from the following sources is required :

1. Existing geological / hydrogeological maps and literature 2. Interpretation of satellite imagery 3. Field visits / surveys.

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As discussed earlier, the primary and secondary geological structures have to be identified and mapped through visual interpretation of satellite imagery taking the help of existing maps / literature. Different structures that have to be mapped have been classified into following 6 groups which have to be represented on the map with appropriate line symbols as shown in the Annexure-II : 1. Bedding 2. Schistosity / Foliation 3. Faults 4. Fractures / Lineaments 5. Shear Zones 6. Folds 7. Trend Lines

The first 4 structures mentioned above, have to be further classified and mapped into different types as discussed in section 6.2.2. Initially, a pre-field structural map overlay has to be prepared which has to be checked in the field wherever they are mapped based on inferences and then, a final map has to be prepared by incorporating the field observations. 7.4 PREPARATION OF GEOMORPHOLOGICAL MAP OVERLAY

The synoptic view of satellite imagery facilitates better appreciation of geomorphology and helps in mapping of different landforms and their assemblage. The photo-interpretation criteria, such as tone, texture, shape, size, location, association, physiography, genesis of the landforms, nature of rocks / sediments, associated geological structures, etc., are to be used for identification of different landforms / geomorphic units. Initially, the entire image has to be classified into 3 major zones, i.e. Hills & Plateaus, Piedmont Zones, and Plains considering the physiography and relief as the criteria. Then, within each zone, different geomorphic units have to be mapped based on the landform characteristics, their areal extent, depth of weathering, thickness of deposition etc as discussed earlier. Subsequently, within the alluvial, deltaic, coastal, eolian and flood plains, individual landforms as listed in Table-3, have to be mapped and represented on the map using the standard alphabetic codes shown against each landform.

These geomorphic units / landforms interpreted from the satellite imagery have to be verified on the ground during the field visit to collect the information on the depth of weathering, nature of weathered material, thickness of deposition and nature of deposited material, etc. For this purpose, nala / stream cuttings, existing wells, lithologs of the wells drilled have to be examined. By incorporating these details in the pre-field interpretation map, the final geomorphic map overlay has to be prepared.

For preparation of geomorphic map overlay, information from the following sources is required :

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1. Lithological map overlays 2. Interpretation of satellite imagery 3. Field visits / surveys.

If previous maps / literature is available, the job becomes easier; even otherwise also, a good geomorphological map showing assemblage of different landforms can be prepared based on the above sources of information. The satellite image along with the interpreted lithological map overlay should be kept on the light table. A fresh transparent overlay should be kept on the top and each rock type should be classified into different geomorphic units / landforms as per the classification system suggested. Sometimes one lithologic unit may be classified into 2 or more geomorphic units / landforms and vice versa. This is to note that wherever the lithologic/ geomorphic boundaries are common, they should be made co-terminus. All the geomorphic units / landforms should be labeled with alphabetic annotation as given in Table-3, e.g. RH, PPS, VFD, etc.

7.5 PREPARATION OF HYDROLOGICAL MAP OVERLAY Satellite imagery provide excellent information on hydrologic aspects like stream/river courses, canals, major reservoirs, lakes, tanks, springs / seepages, canal commands, ground water irrigated areas, etc. Based on visual interpretation of satellite data, all the above information can be derived and mapped.

The hydrologic information, derived from satellite imagery in conjunction with collateral data has to be shown on a separate map overlay in a classified manner with appropriate symbols as indicated in Annexure-III. Further, the observation wells of State and Central Ground Water Depts. and the wells inventoried during field visit have to be marked on this map overlay in a classified manner with appropriate symbols as shown in Annexure-III and as discussed in section 7.7.1.

For preparation of hydrological map overlay, the following sources of information are required - 1. Interpretation of satellite imagery 2. Field visits / surveys 3. Observation well data and 4. Meteorological data

The following details have to be shown in the hydrological map overlay - 1. Canal / tank commands 2. Ground water irrigated areas 3. Well observation data collected in the field and Govt. Depts. 4. Rain gauge stations indicating average annual rainfall. In case of absence of rain

guage station in a toposheet, average annual rainfall in mm has to be given in the legend. Source of rainfall data should be either IMD or District Gazetteer.

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The symbols for representing the above information are given in the Annexure-III Initially, a pre-field hydrological map overlay has to be prepared by visually interpreting the satellite image and taking the help of toposheet. Subsequently, during the field surveys, necessary information on the surface and ground water irrigated areas, cropping pattern, command areas, existing wells, etc have to be collected and incorporated for preparing the final hydrological map overlay.

7.6 FIELD VISIT AND DATA COLLECTION 7.6.1 Planning Before proceeding to the field for ground checks, proper planning has to be made regarding the type of data to be collected and the locations. For this purpose, based on the road network, the doubtful areas marked with question marks while interpreting lithology, landforms, faults, fractures, etc which need to be verified in the field, should be identified and noted in the field note book as well as on the maps. Similarly, the locations of the problematic habitations (as provided by the concerned State Depts.) have to be marked on the map overlays for checking them on the ground for further details. A check list may be prepared indicating the locations and the information to be observed / collected. In addition to this, other areas where well inventory data have to be collected should also be marked on the pre-field hydrological map. It should be planned to collect well inventory data from all the lithologic-landform combinations in such a way that the wells are distributed throughout the map. At least 2-3 wells should be observed in each unit so that the ground water prospects of each unit can be evaluated judiciously. Within each unit also, special care should be taken to observe the depth of weathering, nature of weathered material, thickness and composition of deposited material, etc. The proforma for collecting the lithological / structural / geomorphological / hydrological information and well inventory data, in the field are given in Annexures-V and VI, respectively. These proformas should be xeroxed and used for collecting necessary data in the field. 7.6.2 Verification of Lithological, Structural, Geomorphological and Hydrological Maps

During the field visit, the doubtful areas where the question marks have been indicated on the pre-field interpreted lithologic, structural, geomorphic and hydrological map overlays have to be verified / checked on the ground and necessary corrections / modifications have to be incorporated. In addition, it is also desirable to check the lithological units / rock types, structures and landforms / geomorphic units randomly at some places, where the confirmed boundaries have been drawn, to ascertain the correctness of interpretation. The inferred faults / fractures / lineaments have to be checked on the ground for field evidences. Careful examination of the wells located along the faults / fractures have to be made to observe the effect of these structures on ground water prospects as compared to the surrounding areas. The geomorphic units/ landforms which have to be classified into shallow, moderate and deep categories

36

based on their depth of weathering, thickness of deposited material, etc have to be verified on the ground by observing the nala / stream cuttings, well sections, etc. However, the contacts between shallow, moderate and deep categories of a given geomorphic unit / landform are gradational. The proforma for collecting the lithological / structural / geomorphological / hydrological information in the field is given in Annexure-V. 7.6.3 Collection of Ground Water Information

During the field visit, extensive well observation data has to be collected atleast 80 – 100 wells in each map for proper evaluation of unit-wise ground water prospects in the area. For collecting the well observation data, traverses should be undertaken in such a way that the observations are well distributed through out the area and represent all the units (at least 2-3 wells in each unit). During the field visits, the location of wells observed have to be marked correctly on the map and numbered. The information about the wells has to be filled in the proforma enclosed in Annexure-VI as indicated above. The details to be collected in the field include - type of well, depth to water table, water table fluctuation (i.e. pre- and post-monsoon water tables), yield, total depth of well, type of subsurface formations and any other related information. This information can be collected partly by observing the wells and partly by discussing with well owners, neighbours, villagers, Gram Panchayat representatives etc.

In addition to the above, the data on the observation wells (water table

fluctuations) and the drilling results, pump test data if any available with the State and Central Govt. Depts. have to be collected. 7.6.4 Information about Problem Habitations

The locations of problem habitations (NC and PC habitations) provided by the concerned State Depts, if available in advance, have to be marked on the base map with different symbols as shown in Annexure-I before proceeding to the field. If the locations of NC/PC habitations are not available before proceeding to the field, they have to be collected from district headquarters of the concerned State Depts. in the beginning of the field visit. During the field visit, efforts should be made to visit maximum number of these villages in order to understand the nature of the problem. In case, if the problematic villages are too many and / or not approachable, then a minimum of 40 to 50 villages have to be selected and visited in such a manner that they are well distributed through out the area and represent all the units.

7.7 CORRECTIONS / MODIFICATIONS IN THE LITHOLOGICAL, STRUCTURAL, GEOMORPHOLOGICAL, HYDROLOGICAL AND BASE MAPS

The observations made during field surveys have to be incorporated on all the overlays, i.e. lithological, geomorphological, structural, hydrological and base map overlays, by modifying / correcting the boundaries of the units, renaming the units, etc.

37

Particularly, for classifying and mapping the geomorphic units / landforms and lithologic units correctly, well observations data collected in the field and also from the Govt. Depts. have to be used to know the depth of weathering and thickness of deposited material. Care should be taken that the lithological and landform boundaries, wherever common, should be co-terminus.

The well observation data collected in the field and other depts. should be incorporated in the hydrological map overlay indicating the type of well, its yield range, depth to water table and total depth of the well as shown in Annexure-III.

7.8 PREPARATION OF GROUND WATER PROSPECTS MAP

For preparing the ground water prospects map the following procedure has to be followed:- 7.8.1 DRAFT MAP PREPARATION

First a draft ground water prospect map has to be prepared by manually integrating the information from lithological, structural, geomorphological and hydrological map overlays as indicated below –

1. Take a fresh transparent overlay and transfer the integrated lithologic-geomorphic

units by superimposing the lithological and geomorphological map overlays. These integrated lithologic-geomorphic units are the ‘hydrogeomorphic units’ and have to be annotated with alphanumeric codes, e.g. PPS-71, PPD-81, UPM-32, etc. wherein the alphabetic code represents the geomorphic unit and the numeric code represents the lithologic unit.

2. Transfer the geological structures from the structural map overlay on to the

integrated lithologic-landform map. The geological structures which act as conduits and barriers for ground water movement should be drawn in blue and red pencil colours, respectively as indicated in Plate-1.

3. Transfer the hydrological information including all the drainages and water bodies

from the hydrological map overlay on to the integrated lithologic-landform -structure map.

4. In addition to above, some (to reduce the clumsiness) of the rivers/streams, major

water bodies and metalled roads (including NH & SH) have also to be transferred on the integrated map for control. To avoid the confusion in identification of features, rivers/stream/water bodies have to be drawn in cyan colour and roads in brown colour. However, while preparing the final ground water prospects map prepared digitally, all the rivers / streams and water bodies and entire road network and other details available in hydrology and base layers have to be shown.

5. All the hydrogeomorphic units occurring in the area have to be listed in the legend

following the geological sequence. Then, the ground water prospects of each hydrogeomorphic unit have to be evaluated by considering the lithological,

38

structural, geomorphological and hydrological information. The ground water prospects information has to be furnished in a tabular manner as shown in the map legend (Plate-1).

7.8.2 Digitisation

All the theme layers prepared for each map has to be digitised and an error free

digital data base has to be created. Care should be taken while registering the tick marks on 4 corners of the map. There should not be any mismatch between the digitised features and scanned features. Regarding attributes and look-up tables, see the digitisation guidelines manual. 7.8.3 Generation of final ground water prospects map

All the digitized layers are to be overlaid using one predefined AML programme to come out with the final ground water prospects map. Towards that coverage naming convention should be followed as per digitization guidelines manual. Before running the AML all the extra coverages should be removed from the work space and extra items should be droped from the coverage attribute tables. Refer the AML manual for step-by-step procedure to run the final ground water prospect map composition AML programme.

7.8.4 Ground Water Prospects Evaluation

As mentioned above, based on the lithological, structural, geomorphological and hydrological information, the ground water prospects of each unit have to be evaluated in terms of different parameters as indicated in the legend. Since no separate report has to be prepared for each map, an exhaustive legend has been designed containing two parts. The upper part of the legend provides map unit-wise ground water prospect information and lower part provides the symbology details about the base map, hydrological and geological information, colour scheme for representing the yield range and depth range of wells, location map, toposheet index, administrative index and other reference information. The format of the legend is fixed and it has to be followed strictly to maintain the standards and uniformity. The details which have to be furnished in the upper and the lower parts of the legend are discussed below - Upper Part of the Legend The upper part of the legend, which is meant for showing the unit-wise ground water prospects, is divided into 14 columns. The heading for each column is given in Plate-1. The details to be furnished Column-1 : Map Unit In this column, the information about ‘map unit’ (hydrogeomorphic unit) has to be furnished with alpha-numeric code, where the alphabetic code (alphabets) represents geomorphic unit and numeric code (number) represents lithological unit and both are

39

separated by a dash (e.g. DH-91, PPM-91, etc). Further, the box is filled with colour hatching. The colour represents the yield range of wells and hatching pattern indicates the depth range of wells. While arranging all the hydrogeomorphic units in the legend, the geological sequence should be followed. Within the rock types, the geomorphic units have to be arranged as per the relief (i.e. starting from valleys and plains on the top to hills at the bottom). Column-2 : Geological sequence / Rock Type

In this column, the lithologic units / rock types have to be indicated following the geological sequence (stratigraphy). This column has to be sub-divided into 2 sub-columns .In the first sub-column, name of the Supergroup / Group has been given vertically (with geological age if possible in the brackets). In the second column, rock type / lithologic unit indicating the Formation / Type name has been given horizontally (e.g. BARAKAR SANDSTONE, PENINSULAR GNEISS etc). The code no. appropriate to each has to be given in the brackets after the rock type . The names of the rock types should be given in capital letters.

Column-3 : Geomorphic Unit / Landform In this column, the name of geomorphic unit / landform has given followed by alphabetic codes inbrackets, e.g. VALLEY FILL - Shallow (VFS), BAJADA – Shallow (BJS). All the geomorphic units / landforms within a given rock type have been arranged as per the relief, i.e. starting from valleys and plains on the top and hills at the bottom. The names of the geomorphic units should be given in capital letters.

Column-4 : Depth to Water Table and No. of Wells Observed

In this column, information collected from field work on depth to the water level of summer season / pre-monsoon period (minimum to maximum range in metres) along with the number of wells observed have been given. In the units where no wells are present, there it is mentioned as “No Wells”. Where, wells are not observed, it should be mentioned as “wells not observed”.

Column-5 : Recharge conditions

In this column, the recharge conditions generalised for each hydrogeomorphic unit have been given based on the water availability from rainfall and other sources, and hydrogeomorphic conditions. The recharge conditions have been categorised as excellent, very good, good, moderate, limited, poor or nil .

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Column-6 : Aquifer material In this column, the nature of aquifer material has been indicated for each hydrogeomorphic unit. The aquifer material can be one of the following 6 categories based on their material content. The abbreviation of the appropriate category has to be indicated. Loose Sediments (LS) Mainly Quaternary formations comprising of

unconsolidated sediments represented by coastal, deltaic, eolian, alluvial and flood plains should be indicated under this category.

Permeable Rock (PR) The semi-consolidated sediments and vesicular volcanic rocks having primary porosity and permeability should be indicated under this category.

Weathered Rock (WR) Mainly weathered zones in hard rocks where the occurrence and movement of ground water is controlled by the depth of weathering and the nature of weathered material should be indicated under this category.

Fractured Rock (FR) The fractured zones in the hard rocks which generally act as conduits for movement of ground water should be indicated under this category.

Fissured Rock (FIR) The hard rocks like gneisses, schists, slates, quartzites, limestones, etc having jointing, bedding, cleavage and other weak planes which impart limited porosity and permeability to the rock should be indicated under this category.

Impervious Rock (IR) Massive Rocks without significant porosity and permeability like massive granite, dolerite dyke, etc which act as barrier for ground water movement should be indicated under this category.

Where, more than one category has to be indicated, it should be shown as LS + WR or WR + FIR as the case may be.

Column-7 : Types of Wells Suitable In this column, type of well suitable for that particular hydrogeomorphic unit has been given. This is done based on depth to water table, material content and aquifer characteristics as indicated in table 2. Dug Well (DW) Where, the water table is very shallow and/or aquifers

with low transmissivities are present (weathered, fissured/clayey formations).

41

Bore Well (BW) Where, the water table is deep and/or a thick column of weathered / fractured rocks or semi-consolidated rocks with fairly good transmissivities are present.

Tube Well (TW) Where, loose or collapsible unconsolidated and semi-consolidated sediments with fairly good transmissivities are present.

Dug-cum-Bore Well (DBW) Where, the water toable is at moderate depth, having semi-confined aquifers and the formation is not collapsible.

Dug-cum-Tube Well (DTW) Same as above (DBW), but where the formation is loose and collapsible requiring slotted casing.

Ring Well (RW) Same as DW, but where loose and collapsible formation is present.

If in a particular map unit, more than one type of wells is suitable, they are mentioned in this column in two separate lines giving depth range, yield range and other particulars separately for each type of well.

Column-8: Depth Range of wells (Suggested) In this column, the optimum depth range of wells in metres has been indicated. This depth range should be decided considering the depth to ground water table, the thickness of the aquifer, the depth range of existing wells and knowing the depth range of productive aquifers in the unit. Though in this column, colour scheme-wise the depth range of wells is classified into 3 categories i.e. <30, 30-80 mtr, >80mtr, actual depth range of wells like 40-55 mtr, 70-80mtr, 90-110mtr should be given depending on the situation.

Column-9 : Yield Range of Wells (Expected) In this column, the tentative yield range of the wells has been given in litres per minute (lpm) for bore/tube wells or in cu.m per day for dug wells considering the lithological, structural, geomorphological and recharge conditions supported by limited well observation data. While doing this the average yield of wells in the unit after avoiding the abnormally high and abnormally low yields abserved in some wells. Here, one has to use his judgement based on his hydrogeological experience and knowledge. A more porous and pervious rock cannot give lower yield than a less porous and pervious rocks. Similarly, a shallow weathered zone (PPS) on the same rock cannot give high yield than deeply weathered zone (PPD) Hence, while filling the yield range for each unit, the rock type, landform, recharge condition and other hydrogeological conditions also have to be taken into consideration. It should not be just based on 2-3 wells observed. IBased on such correlation, the expected yield range of wells in lpm or cu.m/day has been fixed for each unit. In those hydrogeomorphic units, where presently

42

no wells are available, a tentative yield range has been given purely based on hydrogeological considerations.

Column-10 : Homogeneity in the Aquifer and Success Rate of Wells The success rate of wells varies from unit to unit depending on the homogeneity in the aquifer. Therefore, after careful analysis of the controlling factors and the well observation data, the success rate of wells (very high, high, moderate, low or poor) has been indicated in the legend for each unit based on the homogeneity in the aquifer. For example, homogeneity in the aquifer and success rate of wells is very high in well sorted semi-consolidated formations like sandstones, whereas they are low/poor in hard rocks (fissured rocks) without fractures and significant weathering. While fixing the success rate of wells, the yield range fixed for the unit also to be kept in mind. Wherever yield range is given high the success rate should be moderate or low, since majority of wells drilled in that unit may not give such high yields. Hence, yield range and success rate are inter-related. Considering these things one has to take the decision.

Column-11 : Water Quality In this column, the ground water quality, i.e. Potable (P) or Non-Potable (NP) has been mentioned for each unit. Wherever the water is non-potable, the reasons for non-potability (e.g. high TDS, high fluoride, high nitrate content, brackishness, etc) have been given in this column.

Column-12 : Ground Water Irrigated area In this column, for each hydrogeomorphic unit, the extent of ground water irrigated area (range in %) has been indicated. This information is mainly based on visual estimation of ground water irrigated areas as seen on the satellite image. The clusters of red patches (ground water irrigated areas) can be clearly seen on the satellite image and its proportion with reference to the total unit has been estimated visually and indicated in this column as 5-10%, <5%, >30% etc.

Column-13 : Recharge Structures Suitable / Priority In this column, the type of recharge structure suitable and priority for taking up recharge structures has been indicated. The type of recharge structure should be decided based on the relief, slope, surface material, availability of water, recharging capability of the aquifer, etc. Based on the suitability, the following types of recharge structures (abbreviations) have been indicated against each unit in the legend. In some cases, even two or three types of recharge structures also can be indicated in the order of priority like CD / PT / D etc.

1. Check Dam (CD) 2. Percolation Tank (PT)

43

3. Invert Well (IW) 4. Subsurface dyke (SD) 5. Desilting of Tank (D) 6. Recharge Pit within the tank (R)

The priority should be decided based on 1) the existing recharge conditions 2) depth to water levels 3) status of ground water exploitation 4) demand for water in the area and distribution of NC/PC habitations, etc. The areas with !) poor–low recharge 2) high exploitation 3) deep ground water table and 4) high demand for water is categorised as high priority and vice versa.

In addition the types of recharge structures suitable for each unit are suggested and the ideal locations for these recharge structures also have been indicated in the ground water prospects map with appropriate symbols.

Columns 13 & 14 are indicating the ground water condition, its explotation and necessary structures required for rechrge the ground water are recommended.

Column-14: Problems / Limitations / Remarks In this column, the problems / limitations with reference to ground water prospects, e.g. caving and collapsing of wells, high failure rate, quality / potability etc. and any other relevant information have been given. In the sedimentary and volcanic formations where the ground water prospects are better in the underlying rock type, such things have also been indicated in this remarks column, which particular zone / stratigraphic unit form the aquifer may also be indicated there. Because of space constraint, it should be indicated in telegraphic language with minimum number of words and preference may be given to such information, which has not been clarified in any other columns of the legend. Lower Part of the Legend

The lower part of the legend comprises of different symbols used in the map to represent the base map details, structural, hydrological and ground water prospects information, location map, toposheet index, administrative index, data used, etc. Most part of it is fixed, however, the following details vary from map to map and have to be given in each map as shown in Plate-1. 1. Data used (details of satellite imagery, toposheet, geological maps consulted, etc.) 2. Name of the organisation involved in preparing the ground water prospects maps in

the box provided under the head “Prepared By”. 3. Location map, toposheet index and administrative index as per the format shown in

Plate-1. 4. Any other information in the box provided (see Plate-1)

44

Other details such as title of the map, scale, north arrow, map sheet no., district

names, etc have to be given as per the format shown in Plate-1.

7.8.5 COLOUR SCHEME

In the final ground water prospects map, hydrogeomorphic units have to be coloured with different hatching patterns based on their yield and depth ranges. For this purpose, VIBGYOR colour scheme with seven colours, i.e. violet to red, have to be used for depicting different yield ranges as indicated in Annexure-IV. Within each yield range, 3 hatching patterns have to be used for depicting the depth range of wells as given in Annexure-IV. Thus, a hydrogeomorphic unit showing one of the three hatching patterns in a particular colour (from violet to red) indicates the expected yield range and suggested depth range of the wells. For example, a unit with horizontal hatching in blue colour indicates that the expected yield range in that unit is 200-400 lpm and the depth range of the well is <20 m. The inselbergs, linear ridges, dykes, etc which act as run-off zones/ barriers for ground water movement, should be indicated with solid red colour, and the hills (SH, DH and RH) and dissected plateaus where the prospects are limited to valley portions only have to be indicated with red hatching.

In addition to the above colour scheme, the rivers / streams and perennial water

bodies / tanks have to be shown in light cyan colour and roads, railways and settlements have to be shown in brown colour. All the faults, fractures / lineaments which mainly act as conduits for ground water movement have to be represented in the map with blue colour. Similarly, the quartz reefs / quartzite bands, pegmatite veins, dykes, shear zones, etc which mainly act as barriers for ground water movement have to be shown in the map with red colour. The unit boundaries (polygon boundaries) and unit annotations have to be represented in black colour as shown in Plate-1. 7.9 QUALITY CHECK

The maps will be quality checked at NRSA / DOS at final stage only. Therefore, it is the responsibility of the work centres to comply with the strict norms of internal quality check to produce a high quality map. Towards this, it is essential for each work centre to have an internal quality expert, who will carryout quality checks at each stage of map preparation i.e. preliminary interpretation, post field work stage, draft map preparation and pre-final stage etc. These quality checks have to be done as per the proforma indicated in Annexure-X and send to NRSA. The final quality check will be conducted by the quality team of NRSA / DOS and the corrections / modifications, if any suggested by the quality team have to be implemented by the work centre and the revised and final maps after the corrections / modifications have to be submitted to NRSA. Major discrepancy observed in non-compliance with the comments of Quality Expert will be noted seriously and it will be reflected on the performance of work centre leading to cancellation of work order.

45

7.10 OUTPUT GENERATION

As mentioned earlier, there are essentially two options for generating and submitting the final outputs. Option-I is for those organisations where the infrastructural facilities for digitisation and hard copy generation do not exist. Option-II is for those organisations where end-to-end facilities for interpretation, digitisation and hard copy output generation are available. Therefore, an organisation can select either of the above 2 options depending upon its infrastructure. The outputs to be generated and to be submitted to NRSA for both the options are as follows –

7.10.1 Option-I

In this option, cartographic outputs of all the 5 map overlays and the ground water prospects map have to be generated. It is to note that though all the features have to be neatly drawn with ink, the annotation / text could be freehand and use of template may be avoided to save time and money. The following outputs have to be generated and submitted to NRSA for taking up digitisation work and generation of soft / hard copies –

1. Original tracing of base map overlay with names of the habitations / villages

(freehand with capital letters). 2. Original tracing of lithological map overlay. 3. Original tracing of structural map overlay. 4. Original tracing of geomorphological map overlay. 5. Original tracing of hydrological map overlay. 6. Original tracing of ground water prospects maps with legend. Other information

which is not covered in the standard legend should also be given. 7. A xerox copy of the ground water prospects map in which the hydrogeomorphic

units have to be coloured by pencil as per the colour scheme suggested in section 7.8.2. Other features, such as drainage, geological structures (carriers and barriers), roads, etc. should be coloured by sketch pens with appropriate colours discussed earlier. The boxes of hydrogeomorphic units in the legend should also be coloured by pencil.

7.10.2 Option-II

In this option, all the 5 map overlays have to be digitised and integrated to create the digital database and to generate the ground water prospects map digitally. The guidelines for digitisation and output generation (soft and hard copies) along with the AML program in ARC/INFO will be supplied by NRSA.

In this case, the following outputs have to be generated and submitted to NRSA–

46

1. Soft copies of lithological, structural, geomorphological, hydrological and base map

overlays, and integrated lithological and geomorphological layer in ‘e00 ‘ format in CD-ROM. These layers should strictly comply with the specifications decided by NRSA (Refer to digitization guidelines of ground water prospects maps, Sep.2000)

2. Soft copy of the plot file of final ground water prospects map in HP-GL/2 format in

CD-ROM. 3. Hard copies (1 no. each) of individual layers, i.e. lithology, structure,

geomorphology, hydrology and base map layers with proper symbolisation and legend on 1:50,000 scale. The lithology and geomorphology layers should be generated as black and white prints and the hydrology, geological structures and base map layers should be generated as colour prints.

4. Hard copies (5 nos.) of ground water prospects maps on 1:50,000 scale colour

prints.

47

8. SCOPE OF GROUND WATER PROSPECTS MAP

The ground water prospects map prepared as per the methodology described in this manual based on the interpretation of satellite imagery in conjunction with limited field surveys and other collateral data indicate the prospective ground water zones in the area. The User Depts. can use these maps for narrowing down the target zones around the problem habitations for detailed ground hydrogeological and geophysical investigations, ultimately to select the sites for drilling. These maps should not be used directly for selection of sites without follow-up ground surveys. It is suggested that detailed hydrogeological / ground geophysical investigations have to be carried out in the prospective zones to obtain the exact information about the weathered zone, fractured zone, thickness of deposited material, depth and thickness of aquifers, presence of fractures in the subsurface and their subsurface configuration, information about the existing wells, etc. Subsequently, based on the confirmatory evidences obtained from ground geophysical / hydrogeological surveys, the sites have to be selected for drilling. Similarly for recharge structures also, though each unit has been evaluated for its suitability for planning different types of recharge structures, the exact site for locating these recharge structures have to be evaluated based on the requirement, nature of underlying aquifer, site conditions, availability of water for recharge, etc. The sites shown in the map for recharge structures are tentative.

Thus, these maps will be useful in narrowing down the target zones for detailed

ground surveys / exploration for selection of sites, both for drilling as well as for taking up recharge structures.

1

ANNEXURE - VIIA Description of Rock Types / Lithologic Units and their Aquifer Characteristics.

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

CODE ROCK GROUP / DESCRIPTION AQUIFER CHARACTERISTICS LITHOLOGIC UNIT ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

1 UNCONSOLIDATED SEDIMENTS

Quaternary sediments associated with alluvial, deltaic, coastal, eolian, flood plains, valley fills, etc. Based on their composition, 7 litho-units are identified in this group as shown below -

Aquifer characteristics depend on the ratio of granular to non-granular sediments. Suitable for shallow tube / filter point / ring wells depending on the thickness of sediments and recharge conditions.

1.1 Alluvium – sand / gravel

dominant Granular sediments comprising sand, gravel, pebbles & cobbles.

Very good aquifers with high porosity and permeability.

1.2 Alluvium – clay dominant Mainly non-granular sediments comprising clay and silt.

Aquicludes with limited permeability; form confining beds for underlying aquifers.

1.3 Alluvium – sand/ silt and clay alternating beds

Alternating sequence of granular and non-granular sediments interbedded.

Granular sediments form semi-confined to confined aquifers with moderate to good permeability. The non-granular sediments form confining beds.

1.4 Colluvium – clay / silt dominant

Mainly clay / silt comprising assorted mixture of cobbles and pebbles.

Aquifers with moderate to good permeability.

1.5 Colluvium – pebble / cobble dominant

Assorted mixture of cobble and pebbles comprising limited clay / non-granular material.

Aquifers with limited to moderate permeability.

1.6 Eolian sand / silt Well sorted sand and silt deposited due to wind action.

Very good aquifer subject to recharge.

1.7 Loess

Wind blown dust accumulated in the desert regions often reworked by streams / rivers.

Moderate aquifers subject to recharge. The dust particles clog the slotted pipes and submersible pumps.

2

2 RESIDUAL CAPPINGS Duricrusts associated with remnants of planar surfaces. Occur as plateaus, mesas, buttes, etc. 5 litho-units are identified in this group as shown below -

Low transmissivities; suitable for large diameter dug wells; bore wells suitable only along fractures. Prospects depend upon geomorphic position and recharge.

2.1 Laterite (Ferricrete) Hard and pisolitic oxidised crust at surface

underlain by soft lithomargic clays formed by deep chemical weathering and enrichment of iron oxides by leaching.

Form aquitards with low transmissivities; suitable for large diameter dug wells; bore wells suitable only along fractures.

2.2 Bauxite (Alecrete) Same as above, but formed due to enrichment of aluminium oxide.

----do----

2.3 Kankar (Calcrete) Produced by the formation of calcium carbonate nodules.

----do----

2.4 Chert (Silcrete) Cryptocrystalline silica; occur as bands or layers of nodules.

----do----

2.5 Detrital Laterite Formed by deposition of laterite / ferrugenous detritus as valley fills.

Aquifers with moderate transmissivities; suitable for shallow bores and small diameter dug wells.

3 Deccan Traps & Intertrappeans

Upper Cretaceous to Palaeocene volcanic flows like Deccan basalts and their equivalents. Based on their aquifer characteristics, 7 litho-units are identified in this group as shown below –

Aquifer characteristics vary greatly depending upon the type of volcanic flow. Suitable for dug wells, bore / tube wells.

3.1 Inter- / Infra-trappean Sand / Clay Bed

Thin beds of semi-consolidated sediments occurring between different lava flows and also at the base of the Deccan traps.

Sand beds form good aquifers with high porosity and permeability. Clay beds form aquicludes.

3.2 Tuffacious Basalt Soft, friable and porous basalt formed mainly by volcanic tuff.

Forms good aquifer with moderate porosity and permeability.

3.3 Vesicular Basalt Hard and vesicular basalt with limited porosity.

Moderate to good aquifers suitable for bore wells and dug wells.

3

3.4 Amygdaloidal Basalt Vesicular basalt filled with amygdales. Limited to moderate aquifers suitable for bore / dug wells.

3.5 Massive Basalt Hard and massive basalt. Fracturing and weathering lead to the development of secondary porosity and permeability.

Forms aquifuge unless faulted, fractured or weathered.

3.6 Columnar Basalt

Basalt occurring as columnar blocks due to close spaced hexagonal joints.

Limited to moderate aquifers suitable for bore / dug wells.

3.7 Red / Green Bole

Red / Green clay beds of 0.5 - 5 m thickness occur between different lava flows.

Aquicludes; act as confining beds for underlying aquifers. Create problems during drilling.

4 OLDER VOLCANICS / METAVOLCANICS / META- SEDIMENTS & OTHERS

Volcanic / metavolcanic / metasedimentary and other rocks of different composition of Precambrian age.

Act as aquifuge, unless highly weathered and fractured.

4.1 Basalt / Meta Basalt Hard and massive basalt with or without metamorphism.

----do---

4.2 Rhyolite / Meta Rhyolite Hard and massive rhyolites with or without metamorphism.

----do----

4.3 Dacite / Metadacite Hard and massive dacites with or without metamorphism.

----do----

4.4

Andesite / Meta Andesite Hard and massive andesites with or without metamorphism.

----do----

4.5 Meta Gabbro Metamorphosed Gabbrones not converted into schist or gneiss.

----do----

4.6 Metabasics Unclassified basic rock suite slightly metamorphosed but not converted into schist or gneiss.

----do----

4

5 SEMI-CONSOLIDATED SEDIMENTS

Upper Carboniferrous to Pliocene sediments comprising of mainly Gondwanas, Rajamundry Sandstone, Nari, Gaj series, Cretaceous beds of Trichy etc, which are partially consolidated, soft and friable having significant intergranular pore spaces. Based on their composition, 7 litho-units are identified in this group as shown below -

Highly productive aquifers suitable for heavy duty moderate to deep tube wells. Aquifer characteristics depend on the sand-shale ratio and recharge conditions. Form very good confined aquifers with artesian condition at places.

5.1

Sandstone / pebble bed / conglomerate

Comprising of dominantly granular sediments with insignificant shale/clay content.


5.2 Shaly sandstone Comprising of dominantly granular sediments with significant shale/clay content.

Good aquifers with high porosity and moderate permeability.

5.3 Sandstone with shale / coal bands

Dominantly granular sediments, interbedded with shale, clay or coal partings.

Very good aquifers. Shale/clay/coal layers form confining beds.

5.4 Sandy shale Comprising of dominantly non-granular sediments with significant sand content.

Aquitards with high porosity and lower permeability.

5.5 Shale with sandstone / limestone bands

Mainly shale/clay, coal, lignite formations with thin sandstone partings.

Sandstones form good confined aquifers subject to sufficient thickness and favourable recharge conditions.

5.6 Shale / coal / lignite

Comprising of dominantly non-granular sediments with insignificant sand content.

Aquicludes with limited permeability.

5.7 Limestone / shell limestone Friable limestone or limestone formed by shell fragments and oolites.


5.8 Limestone and shale mixed sequence

Mixed sequence of limestone and shale having primary porosity and permeability.

Moderate to good aquifers depending on the porosity.

5

6.0 CONSOLIDATED SEDIMENTS Mainly Precambrian to Cambrian sedimentaries of Cuddapah, Delhi, Vindhyan Groups and their equivalents, comprising of fully consolidated sediments without any intergranular pore spaces (except the bedding planes). Based on their aquifer charastristics, 8 litho-units are identified in this group as shown below -

Aquifer characteristics depend mainly on the bedding planes and secondary porosity developed by fractures, joints, foliation, schistosity, cleavage planes etc besides weathering. The porosity and permeability vary widely depending upon the rock type.

6.1 Thin bedded / flaggy sandstone/ quartzite

Thin bedded/ flaggy sandstone / quartzite with a no. of well defined bedding planes.

Aquifers with limited to moderate porosity and permeability due to thin bedded nature.

6.2 Thick bedded / massive sandstone / quartzite

Hard and massive sandstone / quartzite, with very few bedding planes and no intergranular pore spaces.

Aquifuge; fractured or weathered sandstone / quartzite form good aquifers.

6.3 Thin bedded limestone / dolomite

Thin bedded, flaggy limestone / dolomite with a no. of well defined bedding planes.

Aquifers with limited to moderate porosity and permeability due to thin bedded nature.

6.4 Thick bedded / massive limestone / dolomite

Hard and massive limestone / dolomite with very few bedding planes.

Aquifuge; fractured, weathered or cavernous. limestones / dolomites form good aquifers.

6.5 Shaly limestone Dominantly limestone with significant shale content as impurity or with shale intercalations.

Aquitards with limited porosity and permeability imparted by bedding planes.

6.6 Shale with limestone/ sandstone bands/lenses

Mainly shale sequence with bands and lenses of limestone / sandstone.

Aquiclude with good porosity and limited permeability along bedding planes.

6.7 Shale Hard and compact shale / claystone.

Aquitard; very low permeability.

6.8 Conglomerate Hard & massive conglomerate without significant intergranular pore spaces.

Aquifuge; fractured or weathered conglomerate develops limited porosity / permeability.

6

7

MASSIVE IGNEOUS ROCKS

Include a variety of hard and massive igneous rocks with no primary porosity.

Act as aquifuge; ground water prospects depend on weathering and fracturing in these rocks.

7.1 Granitoid rocks /

acidic rocks

Massive igneous rocks of granitic / acidic composition. Actual name of the rock type to be mentioned in the map legend on case to case basis.

----do----

7.2 Alkaline rocks Massive igneious rocks of alkaline composition. Actual name of the rock type to be mentioned in the map legend on case to case basis.

----do----

7.3 Basic Rocks Massive igneous rocks of basic composition. Actual name of the rock type to be mentioned in the map legend on case to case basis.

----do----

7.4 Ultrabasic / ultramafic rocks Massive igneous rocks of ultrabasic composition. Actual name of the rock type to be mentioned in the map legend on case to case basis.

----do----

7.5 Others Massive igneous rocks other than 71-74 referred above.

----do----

8 Gneiss – Granitoid Complex / Charnockite – Khondalite complex / Migmatite

Complex rock suites like Peninsular gneissic complex Bundelkhand gneissic complex, charnockite – khondalite complex and migmatite complexes.

Granites / migmatites act as aquifuge; Gneisses weather faster than granites and form aquifers. Ground water prospects depend on the depth of weathering, intensity of fracturing and recharge.

8.1 Gneiss – granitoid complex

Gneisses and granites occurring together which can not be separately mapped..

Granite forms aquifuge and gneiss forms aquifer depending on the extent of weathering and fracturing, and recharge.

7

8.2 Granitic Gneiss

Mainly comprising of gneisses with granitic lenses.

Gneisses form aquifer depending on extent of weathering and fracturing, and recharge.

8.3 Migmatite complex Hard and massive migmatites. Act as aquifuge unless fractured.

8.4 Migmatite with Granite Lenses

Hard and massive migmatites with lenses of granite.

----do----

9 METAMORPHICS Include a variety of metamorphosed igneous, sedimentary and volcanic rocks.

Ground water prospects depend on secondary porosity developed due to cleavage, schistosity, foliation, fracturing, faulting and weathering, and recharge conditions.

9.1 Gneiss Gneisses of different mineral composition with

crude to well developed foliations. Gneisses form moderately productive aquifers depending on extent of weathering and fracturing, and rechathe rge.

9.2 Schist Crudely foliated schists of different composition. Aquitards with limited transmissivities; fracturing

and weathering improve the ground water prospects to a limited extent.

9.3 Phyllite Crudely foliated phyllites. ----do----

9.4 Slate Slates with well developed slaty cleavage. Aquitards with limited transmissivities; fracturing

and weathering improve the ground water prospects to a limited extent.

9.5 Quartzite Hard and brittle quartzites.

Generally, act as barriers for movement of ground water unless fractured.

9.6 Calc-gneiss / calc-schist

Calcareous gneisses / schists with crude to well-developed foliations.

----do----

9.7 Crystalline limestone Hard and brittle limestone / marble. Generally, acts as barriers for movement of ground water unless fractured.

(Source : Modified after Reddy, 1991)

8

ANNEXURE – VIIB

Description of Geomorphic Units / Landforms And Their Influence on the Ground Water Regime.

(P. R. Reddy, 1991 with minor modifications) -------------------------------------------------------------------------------------------------------------------------------------------------------------------- GEOMORPHIC UNIT / DESCRIPTION INFLUENCE ON GROUND WATER REGIME LANDFORM ---------------------------------------------------------------------------------------------------------------------------------------------------------------------

Hill ranges / Composite Hills (HR/CH)

A group of hills occupying large area having minimum extent of 10 KM in all directions.

Mainly act as run-off zone. Large hills contribute significant recharge to the narrow valleys and other favourable zones within the hills and to the adjoining plains.

Structural Hills (SH)

Linear to arcuate hills showing definite structural trends8.

-- do --

Residual Hills (RH)

A group of hills occupying comparatively smaller area than composite hills ranging from 2 x 2 sq.km to 10 x 10 sq.km.

Limited prospects along valleys and limited recharge potential to the surrounding plains.

Inselberg (I)

Plateaus (PL) Elevated flat uplands occupying fairly large area (greater than 5 km x 5km) and bound by escarpments / steep slopes on all sides. Based on their geomorphic position, they are classified into 3 categories – 1) Upper, 2) Middle and 3) Lower. Further, based on dissection, these Upper, Middle and Lower Plateaus have been further classified into undissected, moderately dissected and highly dissected categories.

Ground water regime on the plateaus depends on their geomorphic position, areal extent, dissection pattern and recharge conditions, besides underlying lithology, fractures and depth of weathering.

- Undissected A plateau (upper / middle / lower) which is fully preserved in its original form and has not been dissected.

Better prospects in the central part. Recharge depends on its relative elevation compared to the surrounding landforms.

9

- Moderately Dissected A plateau (upper / middle / lower) dissected by deep valleys/ gullies changing the original form considerably.

Shallow aquifers partially drain out into the deep valleys formed by dissection.

- Highly Dissected A plateau (upper / middle / lower) more frequently dissected by deep valleys separating into individual mesas / buttes.

Shallow aquifers fully drain out into deep valleys formed by dissection.

Valleys Low lying depressions and negative landforms of varying size and shape occurring within the hills associated with stream / nala courses.

Favourable zones for ground water accumulation. Act as discharge zones at places with springs & seepages.

Fracture / Fault Line (FV) Narrow linear valleys formed along fractures / faults.

Very good recharge from surrounding hills, subject to good rainfall. Ground water prospects depend on the depth persistence and nature of fracture / fault.

Intermontane Valley (IV) Small valleys occurring within the hill ranges / composite hills and residual hills.

Very good recharge from surrounding hills, subject to good rainfall. Ground water prospects depend on the underlying rock types, structures, thickness of valley fill and its composition.

Linear / Curvilinear Ridge (LR / CR)

A narrow linear / curvilinear resistant ridge formed by dolerite dyke, quartz reef, quartzite bed, etc.

Forms divide for both surface & ground water unless cut across by faults / fractures.

Cuesta (C)

An isolated hill formed by gently dipping (5-15o) sedimentary beds having escarpent / steep steep slopes on one side and gentle dip slopes on the other side.

Form run-off zones without any significant recharge potential and prospects.

Mesa (M) Flat-topped hills having width 2 km to 250 m. Form run-off zones without any significant recharge potential and prospects.

Butte (B) Flat-topped hills having width < 250 m ----do---

10

Inselberg (I)

An Isolated hill of massive type abruptly rising above surrounding plains.

Act as run-off zone.

Pediment (PD)

Gently undulating plain dotted with rock outcrops with or without thin veneer of soil cover.

Forms run-off and recharge zone with limited prospects along favourable locales.

Buried Pediment (BPD)

Same as above, but buried under unconsolidated sediments.

Limited to moderate recharge zone depending on the thickness of buried column.

Dissected pediment (DPD)

Same as pediment, but dissected. Shallow aquifers drain out due to dissection.

Pediment-Inselberg Complex (PIC)

Pediment dotted with a number of inselbergs which cannot be separated and mapped as individual units.

Inselbergs form run-off zones. Pediment contributes for limited to moderate recharge.

Piedmont Slope (PS)

Slope formed by bajada and pediment together.

Forms run-off and recharge zone.

Piedmont Alluvium - Shallow (PAS) - Moderate (PAM) - Deep (PAD)

Alluvium deposited along foot hill zone due to sudden loss of gradient by rivers / streams in humid and sub-humid climate. Based on the thickness, it is divided into 3 categories – 1) Shallow (0-10 m), 2) Moderate (10-20 m), and 3) Deep (more than 20 m).

Alluvium forms good shallow aquifer depending on its thickness, composition and recharge conditions.

Bajada (BJ) - Shallow (BJS) - Moderate (BJM) - Deep (BJD)

Detrital alluvial out-wash of varying grain size deposited along the foot hill zone in arid and semi-arid climate. Based on the thickness, it is divided into 3 categories - 1) Shallow (0-10 m), 2) Moderate (10-20 m) and 3) Deep (> 20 m).

Forms highly productive shallow aquifers subject to the thickness of deposited material and recharge conditions.

11


Same as earlier

Same as earlier

Cuesta (C)

----do----

----do----

Mesa (M) ----do---- ----do----

Butte (B)

----do----

----do----

Inselberg (I)

----do----

----do----

Alluvial Fan (AF)

A fan shaped mass of sediment deposited at a point along a river where there is a decrease in gradient.

Form productive aquifers subject to thickness of sediment and recharge.

Talus Cone (TC) A cone shaped deposit of coarse debris at the foot of hills / cliffs adopting the angle of repose.

Form productive aquifers in the lower reaches subject to thickness of sediment and recharge.

Pediplain-Weathered (PP) - Shallow (PPS) - Moderate (PPM) - Deep (PPD)

Gently undulating plain of large areal extent often dotted with inselbergs formed by the coalescence of several pediments. Based on the depth of weathering, weathered pediplains are classified into 3 categories - 1) Shallow (0-10 m), 2) Moderate (10-20 m), and 3) Deep (more than 20 m).

Pediplains occupied by semi-consolidated sediments form good aquifers depending on their composition. In hard rocks, they form very good recharge and storage zones depending upon the thickness of weathering / accumulated material, its composition and recharge conditions. Faults / fracture zones passing through pediplains act as conduits for movement and occurrence of ground water.

Pediplain-Buried (BP) - Shallow (BPS) - Moderate (BPM) - Deep (BPD)

Same as above, but buried under transported material. Based on the total thickness of transported material and depth of weathering, buried pediplains are classified into 3 categories - 1) Shallow (0-10 m), 2) Moderate (10-20 m), and 3) Deep (more than 20 m).

----do----

12

Stripped Plain (SP) - Shallow Basement (SPS) - Mod. Basement (SPM) - Deep Basement (SPD)

Gently undulating plain formed by partial stripping (erosion) of older pediplains. The presence of rock outcrops along valleys and deeply weathered zones along inter-stream divides indicate the stripped plains. Based on depth to basement, it is classified into 3 categories - 1) Shallow (0-10 m), 2) Moderate (10-20 m), and 3) Deep (more than 20 m).

The ground water prospects depend on the depth to basement, faults / fractures passing through the hard rocks and recharge.


Same as earlier

Same as earlier

Cuesta (C)

----do----

----do----

Mesa (M) ----do---- ----do----

Butte (B)

----do----

----do----

Inselberg (I)

----do----

----do----

Valley Fill (VF) - Shallow (VFS) - Moderate (FVM) - Deep (FVD)

Valleys of different shapes and sizes occupied by valley fill material (partly detrital and partly weathered material). They are classified into 3 categories - 1) Shallow (0-10 m), 2) Moderate (10-20 m), and 3) Deep (more than 20 m).

Form moderately productive shallow aquifers, subject to thickness of valley fill material, its composition and recharge conditions.

Fracture / Fault line Valley (FV) Valley (V)

Flood Plain (FP) - Shallow (FPS) - Moderate (FPM) - Deep ((FPD)

Alluvium deposited along the river / stream courses due to repeated flooding. Based on the thickness of alluvium, it is classified into 3 categories - 1) Shallow (0-10 m), 2) Moderate (10-20 m) and (3) Deep (>20 m).

Flood plains receive good recharge and form good shallow aquifers depending on the type of sediments, their thickness and recharge conditions.

13

Alluvial Plain (AP) - Shallow (APS) - Moderate (APM) - Deep (APD)

Flood Plain-Younger / Lower (FPY) - Shallow (FYS) - Moderate (FYM) - Deep (FYD)

Same as above. Younger refers to late cycle of deposition and lower refers to lower elevation. Based on the thickness of alluvium, it is classified into 3 categories - 1) Shallow (0-10 m), 2) Moderate (10-20 m) and (3) Deep (>20 m).

Deltaic Plain (DP) - Shallow (DPS) - Moderate (DPM) - Deep (DPD)

Alluvial plain formed by the distributary network of the rivers / streams at their confluence with sea. Based on the thickness of alluvium, it is classified into 3 categories - 1) Shallow (0-10 m), 2) Moderate (10-20 m) and (3) Deep (>20 m).

These deltaic plains receive very good recharge due to repeated flooding and form shallow aquifers. The aquifer conditions depend upon the nature of sediments and their thickness. Nearer to the coast, they are underlain by marine sediments containing brackish water.

Channel Bar (CB) Sand bar formed in the braided river course due to vertical accrition of the sediments.

Highly productive shallow aquifer with good recharge from the river flow.

Point Bar (PB) Sand bar formed at the convex side of meandering river by lateral accrition of sediment.

Form moderate to highly productive aquifers depending on their thickness and recharge.

River Terrace (RT) Flat upland adjoining the river course, occurring at different levels and occupied by river-borne alluvium. It indicates the former valley floor.

Form good aquifer depending on the thickness of alluvium, composition and recharge.

Natural Levee (NL) Natural embankment formed by deposition of alluvium on river bank due to flooding.

Aquifer condition depends mainly on the grain size of sediments and the recharge.

Back Swamp (BS) Depressions formed adjacent to natural levees in the flood plains of major streams/rivers. Occupied by clay & silt with or without water.

These swamps are temporarily occupied by water. Form aquitards due to the dominance of clayey sediments.

14

Cut-off Meander (CM) Meander loop of a matured river, cut-off from the main stream / river, filled with river-borne sediments.

Highly productive shallow aquifers with good recharge from the river.

Abandoned Channel (AC)

An old river bed cut-off from the main stream, occupied by channel- lag / channel-fill material.

Highly productive shallow aquifers with good recharge from the river.

Ox-bow Lake (OL) A lunate shaped lake located in an abandoned meandering channel.

Generally forms ground water discharge zone with highly productive shallow aquifer.

Palaeochannel (PC) An earlier river course filled with channel

lag or channel fill sediments, which is cut off from the main river.

Forms highly productive shallow aquifer subject to the thickness of sediment, its composition and recharge.

Buried Channel (BC) Old river course filled with channel lag or channel fill deposits, buried by recent alluvium / soil cover.

----do----

Coastal Plain (CP) - Shallow (CPS) - Moderate (CPM) - Deep (CPD)

Nearly level plain formed by marine action along the coast, mainly containing brackish water sediments. Based on the thickness of alluvium, it is classified into 3 categories - 1) Shallow (0-10 m), 2) Moderate (10-20 m) and (3) Deep (>20 m).

Coastal plains are generally occupied by marine sediments containing brackish water. Fresh water occurs as a thin layer floating over brackish water.

Beach (B)

Narrow stretch of unconsolidated sand/silt deposited by tidal waves along the shore line.

Fresh water occurs as a thin layer over the brackish water under favourable morphologic and recharge conditions. Over-exploitation disturbs the sensitive balance between fresh and brackish water resulting in sea water intrusion.

Beach Ridge (BR) A linear ridge of unconsolidated sand / silt parallel to the shore line.

----do----

15

Beach Ridge & Swale Complex (BSC)

A group of beach ridges and swales occurring together.

Fresh water may occur as thin layer in the beach ridges.

Swale (SW) Linear depression occurring between two beach ridges.

Generally, ground water is brackish.

Offshore Bar (OB) Embankments of sand and gravel formed on the sea floor by waves and currents, occurring parallel to the coast line.

----do----

Spit (SP) Off-shore bar attached to the land at one end and terminating in open water at the other.

----do----

Mud Flat (MF) Mud deposited in the back swamps and along tidal creeks.

Form aquiclude due to high clay content.

Salt Flat (SF) Flat lands along the coast comprising of salt encrustations.

Quality of ground water is saline/ brackish.

Tidal Flat (TF) Flat surface formed by tides comprising of mostly mud and fine sand.

----do----

Lagoon (LG)

An elongated body of water lying parallel to the coast line and separated from the open sea by barrier islands.

----do----

Channel Island (CI)

An island formed in the braided river course. Good recharge from river, however, fresh water occurs as thin layer.

Palaeochannel (PC) An earlier river course filled with channel lag or channel fill sediments, which is cut off from the main river.

Forms productive shallow aquifer subject to the thickness of sediment, its composition and recharge.

16

Buried Channel (BC) Old river course filled with channel lag or

channel fill deposits, buried by recent alluvium / soil cover.

----do----

Eolian Plain (EP) - Shallow (EPS) - Moderate (EPM) - Deep (EPD)

A plain formed by the deposition of wind blown sand dotted with a number of sand dunes. Based on the thickness of sand sheet and dissection, it is classified in to 3 categories – 1) Shallow (0-10 m), 2) Moderate (10-20 m), and 3) Deep (more than 20 m).

Eolian plains do not receive good recharge due to scanty rainfall. They form good shallow aquifers depending on their thickness and recharge conditions.

Sand Dune (SD) Heaps of sand of different shapes and sizes formed by wind action in the desertic terrain.

Not suitable for ground water development.

Stabilised Dune (STD) Same as above, but stabilised.

----do----

Dune Complex (DC) Group of sand dunes occuring together which can not be mapped separately.

Very Limited prospects in the interdunal depressions; quality is often brackish.

Interdunal Depression (ID)

Depression occurring between sand dunes. Suitable for water harvesting structures.

Interdunal Flat (IF) Flat land occurring between sand dunes.

----do----

Playa (PL) Dry lake in an interior desert basin. Better prospects, subject to recharge.

Desert pavement (DPV) Flat or gently sloping surfaces, developed on fans, bajadas and desert flats formed by concentration of pebbles after removal of finer material by wind action.

Better prospects subject to sufficient thickness of pebbly zone and recharge.

Loess Plain (LS) Deposit of wind-blown silt. Forms moderate aquifer under favourable recharge conditions.

17

Palaeochannel (PC) An earlier river course filled with channel

lag or channel fill sediments.

Forms highly productive shallow aquifer subject to the thickness of sediment, its composition and recharge.

Buried Channel (BC) Old river course filled with channel lag or channel fill deposits, buried by recent alluvium / soil cover.

----do----

1

ANNEXURE-VIII

ADDITIONAL GEOMORPHIC UNITS / LANDFORMS INCLUDED

PHYSIOGRAPHY GEOMORPHIC UNIT / LANDFORM CODE 1. Hills & Plateaus Plateau – Undissected

Plateau – Slightly Dissected Plateau – Moderately Dissected Plateau – Highly Dissected Plateau - Weathered

PLU PLS PLM PLH PLW

Dyke Ridge / Quartz Reef

Escarpment Slope Hill Slope / Denudational Slope Valley Slope Valley Flat Hill Top - Weathered

DR / QR ES

HS / DS VS VT

HTW

2. Plains Sheet Rock Residual Mound

SR RM

Lateritic Plains Lateritic Plain – With Shallow Basement Lateritic Plain – With Moderate Basement Lateritic Plain – With Deep Basement

LPS LPM LPD

Fluvial Landforms Meander Scar Migrated River Course

MS MR

Coastal Landforms Beach Ridge / Palaeo Beach Ridge Beach Ridge & Swale Complex / Palaeo Beach Ridge & Swale Complex Mud Flat – Younger / Older Offshore Island Reef Island

BR / PBR BSC / PBS

MFY / MFO

0I RI

Note: The gullied, ravenous, dissected and canal command areas within the Plains and Plateaus can be separately mapped by adding G, R, T and C, respectively as the third digit to the alphabetic code of the geomorphic unit, wherever applicable. For example:

Alluvial Plain – Gullied -- APG Alluvial Plain – under Canal Command -- APC Pediplain – Dissected -- PPT Pediplain – under Canal Command -- PPC * These units replace the Plateau terminology given earlier in the Technical Guidelines (February, 2002).

1

METHODOLOGY TO BE FOLLOWED IN DECCAN TRAPS In case of Deccan Traps, the textural characteristics of individual basalt flows and their vertical disposition (or stratigraphy) exercise significant control on the movement and occurrence of ground water. In view of this, mapping of individual basalt flows, which are of generally 10-30 m thickness having horizontal to sub-horizontal dips, has been considered essential. Towards this, the following guidelines/procedures have to be followed. However, in case of Mesa, Butte and Highly Dissected Plateaus, which mainly act6 as run-off zones, instead of delineating individual basalt flows, all of them may be clubbed together and mapped as ‘Group of Flows’. Different geomorphic units that have to be mapped in Deccan Traps, the guidelines for mapping the individual basalt flows and representation of hydrogemorphic units in the map and as well as legend are given below. A model legend is also enclosed (Table-1) for reference.

Geomorphic Units / Landforms to be Mapped: The following geomorphic units / landforms have to be used for mapping geomorphology in Deccan Trap Terrain – Plateau – Undissected -- PLU Plateau – Slightly Dissected -- PLS Plateau – Moderately Dissected -- PLM Plateau – Highly Dissected -- PLH Plateau – Weathered -- PLW Plateau – Canal Command -- PLC Mesa -- M Butte -- B Escarpment Slope -- ES Valley Fill – Shallow / Moderate / Deep -- VFS / VFM / VFD Valley -- V Valley Flat -- VT Intermontane Valley -- IV Fracture / Fault line Valley -- FV Guidelines for Mapping Basalt Flows: The typical characteristic of basalt flows in Deccan Traps is that the contacts between individual / group of flows are generally marked by the presence of escarpments / steep slopes resulting in terraced landscape. These escarpments / steep slopes are often reflected on the satellite imagery, which in turn help to map the flows. However, at some places, these escarpments / steep slopes are not clearly observed or are obscured on the satellite imagery. In such cases, the field checks and the contours of toposheet can be taken as control. Since, the thickness of basalt flows generally varies from 10-30 m and they have horizontal to sub-horizontal dips, the 20 m contours of toposheet provide good control for mapping the flows in addition to satellite imagery and field observations. The procedure for mapping the basalt flows is given here under – 1. Draw all the contours (except where the contour spacing is too close, i.e. where scale of

mapping does not permit delineation of each and every contact) on a tracing film from the SOI toposheet on 1:50,000 scale.

2

2. Keep the tracing over the image and delineate all the flow contacts with the help of these

contours and also using image signatures, existing geological maps / literature. The flow, thus, delineated have to be checked up at places during field visit and confirm the boundaries besides identifying their nature, i.e. Vesicular, Massive, etc. While doing so, it may happen that more than one flow may occur within one unit, however, it is permissible in the present context of mapping.

3. Number all the flows as 1,2,3,……….. from top to bottom based on their elevations. Note

that these numbers represent essentially the basalt flows / group of flows. Instead of lithologic / rock type codes as suggested earlier in the lighological classification system (Table-1 of Technical Guidelines, February 2000), individual basalt flows have to be indicated / represented with these flow nos. only in the map and legend.

4. The individual basalt flows have to be named based on their textural characteristics as

Massive, Vesicular, Amygdalodial, Tuffacious or Columnar / Fractured (Based on ground truth). The units, which consist of multiple flows have to be named as ‘Group of Flows’.

5. In the legend, the type of flow (i.e. vesicular, massive, etc.) along with their elevations

(range in meters above MSL) have to be given for each unit (see Table-1). 6. The inter-/infra-trappean beds, if forming polygons, should be represented as one of the

units in the sequence. Otherwise, they should be indicated in the geological sequence (not in the map) without giving number, but giving the elevation range. Where they are too thin or not well defined, they should be indicated in the ‘Remarks’ column.

Preparation of Legend The following guidelines have to be considered while preparing the legend for Deccan Traps – 1. In column 1 (i.e. Map Unit), the flow numbers should be taken as numeric codes of map

unit instead of lighologic code as discussed earlier. The numeric code (flow no. or range of flow nos. separated by a dash) should be kept in brackets and placed after the alphabetic code representing the geomorphic unit / landform. However, M/B (Mesa / Butte), the numeric code need not be given, and this unit has to be placed as the last unit in the Deccan Traps (refer Table-1).

2. In column 2, sub-column 1 (Geological Sequence / Rock Type), write Deccan Traps

vertically with capital letters as shown in Table-1. In sub-column 2, the list of flows with heading Basalt Flows should be given as shown in Table-1. For each flow no., type of flow (e.g. massive, vesicular, unclassified group, etc) has to be written in 1st line in capital letters and its elevation range (in m MSL) to be given in 2nd line in small letters. Note that the list of flows should also include intertrappeans as discussed earlier. In between two flows, line separator is not required. however, between Mesa / Butte (M/B) unit and the rest of the units in Deccan Traps, line separator is required. Further, for this unit, in place of no. and type of flow, it should be written as On Different Flows in capital letters (see model legend enclosed for reference).

3

3. In column 3, the name of geomorphic unit / landform should be given in capital letters in the 1st line and the elevation range for each unit has to be given in second line.

4. In column 13 (i.e. Recharge Structures), the type of recharge structures suitable should be

mentioned in the 1st line with abbreviations in capital letters (e.g. CD/PT/NB), and priority should be mentioned in the second line as High Priority, Low Priority, etc. This has to be followed for all the units. In this column, indicating with dashes or leaving it blank should be avoided.

5. in column 14 (i.e. Remarks), mention should be made in telegraphic language about the

following aspects, wherever applicable-

(i) Wherever the basalt flow exposed at the surface is not forming an aquifer, mention should be made of the underlying flows or intertrappean beds, if any, which form / likely to form aquifers along with their elevation range (in m MSL).

(ii) Basis for suggesting the depth and yield range of wells should be given. For

example, in a unit if no wells are existing or observed, it should be mentioned as ‘Prospects are inferred as no wells are available’. Similarly, it can be mentioned that ‘Vesicular zone / potential aquifer encountered at … m MSL in few/ …. wells, which needs to be explored / exploited.

(iii) In case of units like Mesa / Butte, etc which are given solid red colour, it should be

written as ‘Run-off zone; Not suitable for ground water development.’

(iv) For the units like Highly Dissected Plateau, which is given red hatching, it should be written as ‘Mainly run-off zone; Prospects limited to valley portions only.’

(v) In case of (iv) & (v), nothing should be written in 4th to 13th columns, and a dash has

to be given (refer Table-1)

(vi) For the units, which are mainly occupied by forest and / or inhabited, the same may be mentioned in the remarks column.

In addition to the above, wherever Very High, High Priority, No Priority or Not Suitable is given in column no. 13, that should be justified in column no. 14 giving reason. For example-

(i) Very high priority for recharge structures, since ground water exploitation is very high / wells dry up during summer.

(ii) No priority for recharge structures, since mainly occupied by forest and no habitation.

(iii) Recharge structures not suitable, since mainly gullied / ravenous area, etc.

4

GUIDELINES FOR SUGGESTING RECHARGE STRUCTURES The objective of suggesting the recharge structures is to augment the ground water mainly for improving the sustainability of drinking water sources. In order to meet this objective, the information on the type of recharge structures suitable in each unit and their tentative locations are essential, in addition to the prioritization of areas (unit-wise). Considering this, for each map unit (hydrogeomorphic unit), the type of recharge structures suitable have to be given by abbreviations as shown below in the 13th column of the legend. In addition to this, in the second line, priority for taking up the recharge structures should be indicated by mentioning as Low Priority, Moderate Priority, High Priority, Very High Priority and Not Suitable. Further, the tentative sites for locating the recharge structures have to be shown in the map. For this purpose, the following broad guidelines are suggested, which can be followed wherever possible for suggesting the suitability, priority and tentative locations of the recharge structures.

Types of Recharge Structures The following types of recharge structures may be considered for suggesting in each map unit-

1. Percolation Tank (PT) 2. Check Dam (CD) 3. Nala Bund (NB) 4. Invert Well (i.e. Recharge Wells) (IW) 5. Desilting of Tank (DT) 6. Recharge Pit (RP)

Note that ‘Subsurface Dyke’ suggested earlier (Technical Guidelines, February, 2000) is replaced by Nala Bund (NB). One or more types of the above recharge structures suitable in each map unit has / have to be given in the 13th column of the legend (e.g. CD/NB/PT).

Prioritization for Recharge Structures As mentioned earlier, in addition to the type of recharge structures, the priority also has to be indicated for each map unit in the 13th column of the legend. For this purpose, depending upon the requirement of recharge in each unit, one of the following categories has to be mentioned in the 13th column of the legend below the type of recharge structures suitable –

1. Very High Priority 2. High priority 3. Moderated Priority 4. Low Priority 5. No Priority 6. Not Suitable.

Example: CD /PT High Priority

5

The prioritization of constructing recharge structures should be based on the following criteria–

1. Presence of NC/PC villages (mainly due to declining of water table)

2. Status of ground water development.

3. Areas where ground water levels are declining fast

4. Areas where water quality problem exists

5. Where natural recharge is poor or limited due to unfavorable hydrogeological

conditions.

It is suggested that in the map units where drinking water sources have dried up / water levels are declining fast / more no, of NC/PC villages are located / percentage of ground water irrigated area is very high / quality problem is reported (which can be improved by dilution through recharge), ‘Very High Priority’ should be indicated. Similarly, the units, which are mainly covered under forests / inhabited / shallow water table having good to excellent recharge from canal commands and surface water bodies and rivers etc, should be given ‘No Priority’. The remaining units may be given the ‘High Priority’ / ‘Moderate Priority / Low Priority. For the zones, which are not suitable for recharge structures, it should be indicated as ‘Not Suitable’. Location of Recharge Structures: The tentative locations of the appropriate recharge structures have to be shown in the map with the respective symbols indicated in the Technical Guidelines (February, 2002). The following broad guidelines may be considered while identifying and suggesting the tentative locations of recharge structures- 1. Check Dam: On the 1st and 2nd order streams along the foot hill zones and the areas with

0-5% slope. 2. Percolation Tank: On the 1st to 3rd order streams located in the plains and valleys having

sufficient weathered zone / loose material / fractures. 3. Nala Bund: On the 1st to 4th order streams flowing through the plains and valleys where

acquisition of land for inundation of large areas is not possible. In this case, limited water will be stored in the river bed for some time which increases recharge.

4. Invert Well: In the areas where transmissivity of the upper strata is poor, e.g. in shales

underlain by sandstones, in buried pediplains with top soil having low permeability, in Deccan Traps where vesicular basalt is overlain by massive basalt or thick black cotton soil (or impervious zone). (i.e.Recharge Well)

5. Desilting of Tank: This should be recommended in several small tanks, which are partially

silted up. Siltation in the tanks may be found by comparative study of image and toposheet apart from other techniques.

6. Recharge Pit: Around the NC / PC habitations where drainage does not exist, e.g. water

divide areas, hill/plateau tops, etc.

6

While showing the recharge structures in the map, the following precautions have to be taken- 1. Recharge structures should be shown about 200-300 m upstream of the problem

habitations. 2. Recharge structures should be suggested mainly upto 3rd order streams and at the most up

to the initial stages of 4th order stream. No recharge structure should be suggested on major streams / rivers occupying large area and forming polygons.

3. Care should be taken to place the recharge structures perpendicular to the drainage. 4. Length of the CD, PT and NB symbols should be more or less through out the map. 5. Recharge structure should not cut across more than one drainage. However, they can be

suggested at the junction of two streams, wherever required.

7

ANNEXURE-IX

RGNDWM Project Phase - II

Improvements / Modifications in the methodology For preparing the ground water prospects maps under RGNDWM project Phase-II, certain improvements/ modifications have been made in the methodology. Hence, all the work centers and the scientists involved in this work are requested to note the following improvements / changes in the “Technical guidelines for preparation of ground water prospects maps” brought out earlier in Feb 2000, based on which the maps were prepared under RGNDWM project Phase-I programme. Field work: Under Phase-II programme, a minimum of 10-12 days effective field work has to be carried out for each map (full toposheet) to collect sufficient ground survey data on geology, geomorphology, geological structures and hydrogeological information, NC / PC habitations etc. Observation of wells: During the field work for each map (Full map covering about 700 Sq. km) a minimum of 80-100 wells have to be observed and represented on the map. These observation wells should be selected in such a way, that they are properly distributed throughout the map covering all the map units. Even in smaller units also, at least 2-3 wells should be observed. In case, if wells are totally absent in a particular unit, then it should be mentioned in the legend as “No Wells”. But, before mentioning the same, one should make himself sure about the absence of wells in that unit. After searching in the entire unit, if wells are not available, then only such statement can be made. Any such wrong statement given will lead to rejection of maps and blacklisting of the concerned scientist, internal quality expert and the work center. While selecting the wells for observation, preference should be given in the following order – Irrigation bore / tube wells: Water supply bore / tube wells Irrigation dug wells Hand-pump wells (drinking water) Dug-wells community water supply Dug-wells individual house Further, preference should be given to the wells located outside the village since, they will not clash with the village symbol while representing on the map. In a bore / tube-well, where it is not possible to measure the water level, the depth to water level in a near by dug-well may be observed and mentioned for reference purpose. For ascertaining the yield range, wherever pumping is in progress or switching on the pump is possible, the yield may be measured by filling the bucket of known quantity (15-20 liters capacity) several times noting the time in seconds. The yield should be calculated based on the average time taken for filling the bucket of known quantity. Where, pumping is not in progress, the yield may be estimated as shown below by noting the diameter of the delivery pipe i.e. 2”, 2 ½”, 3” etc. full delivery, ½ delivery, ¾ delivery or delivery with gaps etc. by discussing with the well owner / farmer.

1

Yield Ranges (in lpm)

Water flow 2” dia pipe 21/2” dia pipe 3” dia pipe

Half (½) delivery (Half pipe)

10-50 15-75 22-112

Three-fourth (¾) delivery (three-fourth pipe)

50-75 75-112 112-168

Full delivery (full pipe)

75-100 112-150 168-225

Full pipe with pressure up to 1ft distance

100-150 150-225 225-337


150-200 225-300 337-450


200-250 300-375 450-560

For final representation on the map, 80–100 wells are sufficient. However, for fixing the average yield for each unit, it is advisable to take into consideration the yield information of several wells in each unit by discussing / enquiring with farmers and villagers. While fixing the average yield range, the wells with abnormally low and high yields should be avoided, where abnormally high yields are noticed in the hard rocks i.e. >200 lpm, the reasons also should be verified and possibility of its occurrence on fracture zones may be checked by examining the satellite imagery. If any fracture / lineament is inferred on the satellite data, some more wells should be observed along such zone to confirm the existence of fracture and represent the same on the map as ‘confirmed fracture’ with solid line symbol. Observation of rock types: All the rock types that have been demarcated on the satellite imagery (with or without the help of previous literature / existing maps) should be verified on the ground at several places and confirmed. Ultimately, based on the field verification only, the nomenclature of rock type and rock codes to be finalized, not based on previous literature. Previous literature may be taken as a guide, but its confirmation on the ground and collection of few typical rock specimens is essential. The boundaries between different rock types should be observed at several places on the ground and confirmed. The boundaries taken from previous geological maps should not be taken as it is. They have to be superimposed on the imagery and adjust the boundaries taking into account the image characteristics. However, these boundaries have to be checked at several places on the ground and satisfied. Observation of geological structures: The minor geological structures like strike and dip of bedding in sedimentary rocks, foliation in metamorphic rocks and major joints in igneous rocks to be marked wherever rock out crops are observed. Searching for outcrops and measuring strike and dip (bedding / foliation / joints) and representing them with appropriate symbols on the map is essential. Unless, a particular rock type is totally covered by soil and not exposed anywhere except in the well sections and nala cuttings. Trends observed on satellite imagery may be taken as a guide for determining the strike and dip. But, without examining the same on the ground, the strike and dip symbols should not be marked on the map.

2

In hard rock areas, since, fracture zones act as conduits for ground water movement, their importance in selection of well sites needs no emphasis. Hence, majority of lineaments interpreted form satellite imagery should be verified on the ground and where evidences are very clear, they have to be shown on the map ‘as confirmed’ with solid line symbol. The lineaments which have no evidences on the ground should be deleted from the map and the others which have limited evidences have to be shown with dashed line symbols as ‘inferred’ category. Considering the importance of this information, it is essential to pay sufficient attention to confirm as many lineaments as possible during the field work. Observation of geomorphic units: All the geomorphic units interpreted from satellite imagery should be cross verified on the ground and confirmed. The depth of weathering and thickness of deposition (whatever / wherever applicable) should be verified for each geomorphic unit at several places to facilitate proper classification of the same into shallow (1-10 mtrs.) moderate (10-20 m) and deep (>20 m) categories. In the legend also, wherever shallow, moderate and deep are added to any geomorphic unit as suffix, the actual depth range / thickness observed on the ground should be indicated below that unit in the brackets as (5-8m) etc. Edge matching: Before finalisation of the maps, edge matching with the adjacent maps is a must. Hence, the concerned work center has to take care of edge matching of all the maps by consulting the concerned state project coordinator / project manager about the distribution of adjacent maps. Quality Check: The maps will be quality checked at NRSA / DOS at final stage only. Therefore, it is the responsibility of the work centres to comply with the strict norms of internal quality check to produce high quality maps. As, strategic partners of NRSA, all the work centers have to take the responsibility for producing high quality maps with sufficient field data. To achieve, it is essential for each work centre to have an internal quality expert, who will carryout quality checks at each stage of map preparation i.e. preliminary interpretation, post field work stage, draft map preparation and pre-final stage etc besides providing technical guidance to the scientists. These quality checks have to be done as per the proforma indicated in Annexure-X and send to NRSA. The final quality check will be conducted by the quality team of NRSA / DOS and the corrections / modifications, if any suggested by the quality team have to be implemented by the work centre and the final maps after incorporating the corrections / modifications have to be submitted to NRSA. Any discrepancies observed in complying with the modifications / corrections suggested by the Quality Expert will be noted seriously and will be reflected on the performance of work centre leading to cancellation of work order. The guidelines given above have to be followed very strictly. If any map does not contain the required field information or edge matching is not done with the adjacent maps, it will be rejected at any stage even if it has passed through regular quality checks and payment is released also. Thus, for insufficient field data and problems in edge matching, the total responsibility rests with the concerned work centers. Hence, all the work centers have to be extra cautious in collecting required field information and confirming the interpretations made based on satellite data and other sources and edge matching of all the maps before their submission to NRSA. Due to unforeseen reasons, if sufficient field work is not carried out in a particular mapping unit, it should be mentioned in the remarks column indicating the reasons. If, it applies to a larger area or the entire map, it should be indicated as foot note below the legend.

4

PROCEDURAL GUIDELINES TO BE FOLLOWED

FOR PREPARING THE GROUND WATER PROSPECTS MAPS

1. Total drainage from toposheet should be traced on to a 50 or 75 micron tracing film using

very thin and dull back colour pen (ball point or rotring pen). Over the hills and high relief areas, some of the 1st order drainage may be omitted to avoid clumsiness, but none of the 2nd order streams have to be omitted.

2. The drainage overlay should be superimposed on to the satellite imagery and match both

the drainages by making best fit adjustment. 3. Transfer the lat-long ticks (+marks) from the image on to the drainage overlay for

reference. 4. Along major rivers and streams where changes in the river / stream courses is more

common, necessary corrections in the drainage courses may be made using image interpretation.

5. Hanging drainages lines, if any, should be connected using image control. 6. New water bodies, tanks, canals etc if any seen on the imagery to be marked on to the

drainage overlay. 7. The drainage overlay should be used for interpretation of all themes. 8. On the drainage overlay, transfer the geological / lithological boundaries from the known

sources / literature / existing geological maps. 9. Make necessary corrections in the lithologic boundaries based on tone, texture, assemblage

and other information observed on the image. Confirmed boundaries to be marked with solid lines and inferred boundaries with dashed lines.

10. Then, the overlay should be superimposed on to the toposheet and all the hills, inselbergs,

mesa / butte, plateau etc to be marked based on contour information. Then, the overlay should be superimposed on to the image and correct the boundaries of the hills, inselbergs, mesa / butte / plateau etc seeing the image.

11. Wherever too many inselbergs are occurring, PIC boundary should be drawn enclosing all

such inselbergs seeing image tone, texture assemblage etc. 12. Along major rivers and streams, fluvial landforms like point bar, channel bar, migrated

river course, palaeochannel, floodplain, alluvial plain etc. to be marked. 13. After marking the above landforms, the remaining area between the hills and valley

(stream) should be divided into PPS / PPM / PPD etc. 14. Wherever intensive gullying is seen, it should be marked as PPG, APG, FPG, EPG, CPG

etc. 15. Wherever canal command is seen on the plains and plateaus, they should be marked as

PPC, APC, FPC, EPC, CPC etc. as the case may be.

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16. Thus, after demarcating all the landforms, the lithologic and landform boundaries should

be made co-terminus and drawn using colour pencil. 17. For all the hydrogeomorphic units, thus mapped, alpha-numeric annotation to be given. 18. Faults should be marked where evidences are clearly observed, i.e. shifting in the

alignment of dykes, linear ridges, juxtaposition of the rock types etc. is observed. 19. Faults having positive topographic expression should be mapped as shear zones. 20. All the fractures and lineaments should be marked seeing the image and drainage

alignment. 21. The lineaments which are not forming parallel sets to be removed, if evidences are not

very clear on the image. 22. Those lineaments having definite evidences should be marked as confirmed with solid

lines and the remaining ones with dashed lines. 23. Based on their length, the major lineaments (>3 km) to be marked with thick line and the

minor ones (<3 km) with thin lines. 24. Now, since total interpretation is complete, individual layer-wise information may be

separated, i.e. lithology, landform, geological structures from this overlay. 25. The hydrogeomorphic boundaries which need to be checked up in the field should be

transferred on to the toposheet. For this purpose, the toposheet to be kept on the map overlay on the light table and the unit boundaries and lineaments that need to be checked in the field should be marked on to the toposheet using pencil.

26. Then seeing the road network, accessibility etc. on the toposheet, the points for field

check should be decided based on the information to be collected in the field. These field check points should be numbered as (1), (2), (3) etc. on the toposheet with red colour pencil. About 40-50 such points to be identified for checking in the field; this is in addition to well observations.

27. What type of information to be collected in the field points at (1), (2), (3) etc should be

clearly noted down in the field note book. 28. At this stage, QC-1 to be conducted and people should be allowed to go for field checks. 29. During the field visit, all the points marked in the toposheet should be verified and

information collected in addition to observing at least 40-50 wells in each toposheet, in such a way that these wells are distributed throughout the map in all the units. Preference should be given to bore-tube wells; where bore/tube wells are not available, dug wells information may be collected.

30. After returning from the field, first field data should be checked up and unwanted,

disputed and irrelevant information to be removed.

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31. In the light of the field observations, necessary corrections to be effected in the integrated overlay as well as individual overlays.

32. Then, legend to be prepared for the total map, colour coding to be given in the boxes

for all the units using colour pencils.

33. At this stage, one internal QC to be done by the specialist of the concerned work center.

34. Then, QC expert to be called for conducting QC-II.

35. After QC-II, necessary modifications and corrections should be incorporated. An ammonia xerox copy of the integrated map overlay to be taken and coloured with colour pencil as per the colour coding (hatching). The legend should be neatly typed on to an A-3 size sheet.

36. This should be shown to the Quality Expert and his signature should be taken on the

map and legend, then, go for digitization.

37. After digitization, a draft ground water prospects map (hard copy output) should be taken and shown to QC expert for conducting QC-III. After QC-III, if the changes / modifications are very few, by incorporating them, the final maps (5 copies of ground water prospects map + 1 copy each of the individual map overlay) and soft copy may be generated and send them to NRSA duly certified by the Quality Expert. If more number of corrections are involved, after incorporating them a fresh output to be taken and shown to the Quality Expert. After the Quality Expert’s approval only, remaining copies to be generated and submitted to NRSA (duly certified by the Quality Expert). The details of deliverables / outputs to be submitted to NRSA are given in the Technical Guidelines.

7

ANNEXURE-IX

RGNDWM Project Phase - II

Improvements / Modifications in the methodology For preparing the ground water prospects maps under RGNDWM project Phase-II, certain improvements/ modifications have been made in the methodology. Hence, all the work centers and the scientists involved in this work are requested to note the following improvements / changes in the “Technical guidelines for preparation of ground water prospects maps” brought out earlier in Feb 2000, based on which the maps were prepared under RGNDWM project Phase-I programme. Field work: Under Phase-II programme, a minimum of 10-12 days effective field work has to be carried out for each map (full toposheet) to collect sufficient ground survey data on geology, geomorphology, geological structures and hydrogeological information, NC / PC habitations etc. Observation of wells: During the field work for each map (Full map covering about 700 Sq. km) a minimum of 80-100 wells have to be observed and represented on the map. These observation wells should be selected in such a way, that they are properly distributed throughout the map covering all the map units. Even in smaller units also, at least 2-3 wells should be observed. In case, if wells are totally absent in a particular unit, then it should be mentioned in the legend as “No Wells”. But, before mentioning the same, one should make himself sure about the absence of wells in that unit. After searching in the entire unit, if wells are not available, then only such statement can be made. Any such wrong statement given will lead to rejection of maps and blacklisting of the concerned scientist, internal quality expert and the work center. While selecting the wells for observation, preference should be given in the following order – Irrigation bore / tube wells: Water supply bore / tube wells Irrigation dug wells Hand-pump wells (drinking water) Dug-wells community water supply Dug-wells individual house Further, preference should be given to the wells located outside the village since, they will not clash with the village symbol while representing on the map. In a bore / tube-well, where it is not possible to measure the water level, the depth to water level in a near by dug-well may be observed and mentioned for reference purpose. For ascertaining the yield range, wherever pumping is in progress or switching on the pump is possible, the yield may be measured by filling the bucket of known quantity (15-20 liters capacity) several times noting the time in seconds. The yield should be calculated based on the average time taken for filling the bucket of known quantity. Where, pumping is not in progress, the yield may be estimated as shown below by noting the diameter of the delivery pipe i.e. 2”, 2 ½”, 3” etc. full delivery, ½ delivery, ¾ delivery or delivery with gaps etc. by discussing with the well owner / farmer.

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Yield Ranges (in lpm)

Water flow 2” dia pipe 21/2” dia pipe 3” dia pipe

Half (½) delivery (Half pipe)

10-50 15-75 22-112

Three-fourth (¾) delivery (three-fourth pipe)

50-75 75-112 112-168

Full delivery (full pipe)

75-100 112-150 168-225


100-150 150-225 225-337


150-200 225-300 337-450


200-250 300-375 450-560

For final representation on the map, 80–100 wells are sufficient. However, for fixing the average yield for each unit, it is advisable to take into consideration the yield information of several wells in each unit by discussing / enquiring with farmers and villagers. While fixing the average yield range, the wells with abnormally low and high yields should be avoided, where abnormally high yields are noticed in the hard rocks i.e. >200 lpm, the reasons also should be verified and possibility of its occurrence on fracture zones may be checked by examining the satellite imagery. If any fracture / lineament is inferred on the satellite data, some more wells should be observed along such zone to confirm the existence of fracture and represent the same on the map as ‘confirmed fracture’ with solid line symbol. Observation of rock types: All the rock types that have been demarcated on the satellite imagery (with or without the help of previous literature / existing maps) should be verified on the ground at several places and confirmed. Ultimately, based on the field verification only, the nomenclature of rock type and rock codes to be finalized, not based on previous literature. Previous literature may be taken as a guide, but its confirmation on the ground and collection of few typical rock specimens is essential. The boundaries between different rock types should be observed at several places on the ground and confirmed. The boundaries taken from previous geological maps should not be taken as it is. They have to be superimposed on the imagery and adjust the boundaries taking into account the image characteristics. However, these boundaries have to be checked at several places on the ground and satisfied. Observation of geological structures: The minor geological structures like strike and dip of bedding in sedimentary rocks, foliation in metamorphic rocks and major joints in igneous rocks to be marked wherever rock out crops are observed. Searching for outcrops and measuring strike and dip (bedding / foliation / joints) and representing them with appropriate symbols on the map is essential. Unless, a particular rock type is totally covered by soil and not exposed anywhere except in the well sections and nala cuttings. Trends observed on satellite imagery

9

may be taken as a guide for determining the strike and dip. But, without examining the same on the ground, the strike and dip symbols should not be marked on the map. In hard rock areas, since, fracture zones act as conduits for ground water movement, their importance in selection of well sites needs no emphasis. Hence, majority of lineaments interpreted form satellite imagery should be verified on the ground and where evidences are very clear, they have to be shown on the map ‘as confirmed’ with solid line symbol. The lineaments which have no evidences on the ground should be deleted from the map and the others which have limited evidences have to be shown with dashed line symbols as ‘inferred’ category. Considering the importance of this information, it is essential to pay sufficient attention to confirm as many lineaments as possible during the field work. Observation of geomorphic units: All the geomorphic units interpreted from satellite imagery should be cross verified on the ground and confirmed. The depth of weathering and thickness of deposition (whatever / wherever applicable) should be verified for each geomorphic unit at several places to facilitate proper classification of the same into shallow (1-10 mtrs.) moderate (10-20 m) and deep (>20 m) categories. In the legend also, wherever shallow, moderate and deep are added to any geomorphic unit as suffix, the actual depth range / thickness observed on the ground should be indicated below that unit in the brackets as (5-8m) etc. Edge matching: Before finalisation of the maps, edge matching with the adjacent maps is a must. Hence, the concerned work center has to take care of edge matching of all the maps by consulting the concerned state project coordinator / project manager about the distribution of adjacent maps. Quality Check: The maps will be quality checked at NRSA / DOS at final stage only. Therefore, it is the responsibility of the work centres to comply with the strict norms of internal quality check to produce high quality maps. As, strategic partners of NRSA, all the work centers have to take the responsibility for producing high quality maps with sufficient field data. To achieve, it is essential for each work centre to have an internal quality expert, who will carryout quality checks at each stage of map preparation i.e. preliminary interpretation, post field work stage, draft map preparation and pre-final stage etc besides providing technical guidance to the scientists. These quality checks have to be done as per the proforma indicated in Annexure-X and send to NRSA. The final quality check will be conducted by the quality team of NRSA / DOS and the corrections / modifications, if any suggested by the quality team have to be implemented by the work centre and the final maps after incorporating the corrections / modifications have to be submitted to NRSA. Any discrepancies observed in complying with the modifications / corrections suggested by the Quality Expert will be noted seriously and will be reflected on the performance of work centre leading to cancellation of work order. The guidelines given above have to be followed very strictly. If any map does not contain the required field information or edge matching is not done with the adjacent maps, it will be rejected at any stage even if it has passed through regular quality checks and payment is released also. Thus, for insufficient field data and problems in edge matching, the total responsibility rests with the concerned work centers. Hence, all the work centers have to be extra cautious in collecting required field information and confirming the interpretations made

10

based on satellite data and other sources and edge matching of all the maps before their submission to NRSA. Due to unforeseen reasons, if sufficient field work is not carried out in a particular mapping unit, it should be mentioned in the remarks column indicating the reasons. If, it applies to a larger area or the entire map, it should be indicated as foot note below the legend.

rgndwm manual april, 2003 final

Documents

lr cr

pay sufficient attention

fresh water occurs

channel fill deposits

carryout quality checks

regular quality checks

fracture lineament

corrections modifications