Chapter I

INTRODUCTION

1.0 Introduction

Morphogenetic parameters such as climate, structure and lithology, resultant

drainage, and slope have direct bearing on the choice of natural landuse practices. It

becomes thus imperative that the physical limiting parameters must be reckoned with

while opting for landuse planning. In many developing countries, the primary landuse

determinants have been economic, social and political, whilst the physical determinants

have been ignored. It is now increasingly realised that analysis of terrain condition should

precede landuse planning . To be more precise, terrain evaluation comprises land

classification and creation of a data bank of parametric base taking into account all the

genetic factors to meet the practical requirements of any landuse planning. The reliability

of information depends on the accuracy of data on different terrain attributes, lithological

sequences, natural vegetation, geomorphic and pedologic development (Pathak, 1982).

Inversely, sustained landuse practices exert lasting impact on the landform features and

often conceal1 modulate manifestations of the dynamic processes taking place in the

earth's near surface. Landuse pattern of an area is the outcome of the interrelationship

between people living therein and its environment. Apparently static land can be highly

mobile through uses. Terrain type and environment determine the landuse pattern of an

area, whereas, landuse practices itself, can contribute to the alteration of the landscape

having long-term manifestations. Increased human activities, and consequent demand on

natural resources especially in the Kerala's context, have resulted in a plethora of changes

in landuse mosaic and morphological features, which have caused irreversible alteration

to the bio-physical foundation. Many of these alterations could lead to severe

environmental degradation and resource depletion, having serious repercussions on

State's economy. These changes have generally gone unnoticed or unrecorded. As a

result, there are little or no attempts to study thcsc issues in proper perspective capturing

all the underlying processes and future consequences. Few studies have been attempted

to highlight impact of various landuse practices on the morphogenetic processes. In a

State like Kerala, where landscape has been intensely modified to accommodate diverse

landuse types within a very limited space and time frame, it is essential to undertake a

diagnostic assessment of landuse pattern as a modifier of the geoecological processes. In

order to cany out such an in-depth study on the direct impact of geomorphological

features on the selection of landuse type, and the latter's impact on the landform, a small

river basin in Kollam district of south Kerala, namely the Ittikara river basin, has been

selected.

1.1 Conceptual background

Geomorphology is the science concemed with the study of the form of the earth.

Analysis of landforms, its evolution and change constitute the core elements of the

subject. Davisian concept (1899) of "Landform as a function of structure, process and

stage" provided the foundation for significant geomorphic enquiry attempting to study

the landform from structural, geomorphologic point of view and to understand the

erosion cycle. It has been acknowledged, that a complete understanding of the

geomorphic processes is necessary for the advancement of our understanding of

landforms, although there was little substantive investigation of processes by

geomorphologists prior to 1960 (Derbyshire et. al., 1979). The denudative processes

taking place on the earth surface is variously affected by climatic factors. Considering the

importance of climate in sculpturing the landscape, a branch of investigation of

geomorphology commonly known as "climatic geomorphology" has evolved. Process

studies, though owes its origin partly to climatic geomorphology, could evolve as a

separate approach particularly with introduction of system theory and quantitative

analysis. Chorley (1971) identified two distinct lines of investigations in physical

geography: (i) process-response systems by the study of contemporary processes, their

character as a response to external constraints and their effects and (ii) study of the

evolution of landscape and landforms concemed primarily with historical development

and chronology. These two distinct lines of investigations are oRen found to overlap and

draw from one another. Jennings (1 97 3) identified six approaches in geomorphological

research within the realm of physical geography (Table 1.0). Process study figures either

as one of the specific lines of enquiry or as a part of climatic geomorphology, and general

systems approach.

Geomorphic research on processes has gained significant importance over time.

A major impetus came from the Geographers of Germany, France, the erstwhile Soviet

Union and East European Countries, who attempted process studies as an integrative

function of land. The works of BudeI (1977), Tricart and Cailleux (1972), Prokayev

(1 962), Isanchenko (1 973), Richling (1 976) among others bear testimony to the

awareness for the need for process studies in geography. Some of these studies also

attempted to understand the nature of environmental interrelationships,

TABLE I .O APPROACHES IN GEOMORPHOLOGY RESEARCH

1 Denudation chronology I Elucidation of stages of evolution, study of the 1 Approach Field of study

Climatic geomorphology

describe the nature of landforms and their spatial I att tern

Davisian trilogy of structure, process and stage. Recognition of morphogenetic systems, evolving under combination of exogenic processes, varying

Morphometry

1 General systems approach I .

1 Study of process-form relationship adopting concepts 1

particularly with climate Application of quantitative techniques to define and

understanding processes in physical or chemical I terms

Process study

1 Structural geomorphology I I Study of the influence of type and rock disposition

Source: Jennings (1 973), Derbyshire et. a/. (1 979).

from thermo-dynamics Quantification of present processes and

Morphogenic regions (Fig 1 .O) have been identified in relation to rainfall and

temperature by Peltier (1950). This scheme of classification applicable in global scale

defines morphogenetic region as a region in which a distinctive complex of erosional,

transportational and depositional processes is responsible for landform development. The

dynamic1 system approach giving emphasis on process measurement and the relation

between process and form has been successful in identifying many features of landscape

that appear to show consistent relationship between inputs and outputs or form (Renwick,

1992). The equilibrium concept and the idea of positive feedback and thresholds

(Langbein and Leopold, 1964; Schumm, 1977, Thomes, 1983) in geomorphology

emanated from this emphasis on process studies.

MORPHOGENIC REGIONS DOMINANANT PROCESSES I I

-10-

F - d O - t

6 c.

Mechanical and / - Chemical weathering, I

2 + l o - r: /" running water / - t m mass movement ,/ t ' .. 0 ,'

2 +20 - Mechanical

running water I I I I

0 2000 1500 1000 500 0

Mean annual rainfall (mm)

Source: Peltier (1 950).

Fig. 1.0 MORPHOGENIC REGIONS AND DOMINANT PROCESSES AS RELATED TO MEAN ANNUAL RAINFALL AND TEMPERATURE

Morphogenetic processes fashioning the landform from earth materials can be

classified as endogenetic and exogenetic. The endogenetic processes are energy forces

acting from within the earth's crust and include crust a1 or non-isostatic warping within

the mantle, earthquake, folding, faulting, metamorphism etc. The exogenetic processes

cover weathering, and surface processes under the influence of climate. The duration,

frequency and effectiveness of geomorphic processes record wide distinguishing features

in long-time unit that are reflected on landforms. The maturity and chronological

sequence of landforms as well as the depositional pattern help reconstruction of climatic

changes. However, while analysing the sequence of fluvial or slope deposits, it may be

concluded that the deposition represents only a small fragment of time and on the

contrary much longer time intervals are reflected in a hiatus or in erosional surfaces

(Starkcl, 1977).

The present-day geornorphic processes act in smaller time frame, following the

seasons of the year, especially the annual sequence of water circulation. The tropics,

characterised by heavy seasonal rainfall and high temperature experience fluctuation in

water and sediment production and movement due to monsoonal effect. The seasonal

factor data can be used in classifying geornorphic process (Wilson, 1973). There are two

group of processes in an annual cycle- the secular and the episodic group of processes.

The secular processes are characterised by low intensity and long duration, and the

episodic processes are of very low frequency and act only during several days or even

hours in a year. Among the secular processes, it is possible to distinguish continuous

processes such as chemical denudation (solution) going on in soil throughout the year and

seasonal or periodic processes such as slope wash, cryogenic processes or transport of the

suspended load in rivers (Starkel, 1985).

Whether the process is of short-time annual duration or of long-time duration, the

modifying factors over the climatic parameters are the vegetation types or more

particularly cover types. Vegetation is considered to be an indirect impact of climate. In

a given climatic environment the plant cover modifies the morphogenetic processes, but,

in turn the latter influence the ecologic conditions (habitat) and thus have repercussions

on the vegetation (Tricart and Cailleux, 1972). The plant formation types interpose a

screen of variable importance between the agents of the weather and the lithosphere.

Depending on the density of undergrowth, vegetation plays an important role as filtering

mechanism. It has to be taken note of that it is seldom the climatic factors of precipitation

and temperature alone which determine the morphological forms. Important

morphological changes may take place through alterations in the vegetation which are

instigated by human activities rather than climatic condition (Zonneveld, 1975). Given

the complex interrelationships of geology, climate, plant, landform and soil in activating

morphogenetic processes, it is quite natural that the concept of scale has to be addressed

while considering the interaction of various morphogenetic factors. Morphogenetic

processes are greatly influenced by plant formation types on a world scale or macro scale.

On a regional scale there is an interplay of pedologic, palaeoclimatic and biogeographic

influences on the morphogenetic processes and, anthropogenic activities are the most

important universal modifier of morphogenetic processes. Further down in a local scale,

the plant species/ vegetation types are the indicators of morphogenetic processes. In

addition there is an interaction between morphogenic and pedogenic processes at the site

level. Identification of top0 sequence and its relation to soil catena forms an important

research problem in soil geography.

Spatial variability of geomorphic processes encountered on earth surface has led

to enquiries that seek identification of homogenous units. However, homogeneity itself

needs to be defined in terms of the amount of variability accommodated within such unit

(Caine, 1982) and the type and number of criteria considered. Land, as defined by

Mabbutt (1968) "is a complex of surface and near surface attributes significant to man"

and Gardiner (1976) stated that "land refers to all those physical and biological

characteristics of the land surface which affect the possibility of landuse".

Most of the land classification systems taking a broader view attempt to

encompass all environmental components, whether or not they are relevant directly or

indirectly to man's use of the land. Moss (1 983) proposed a land classification scheme

by incorporating process data (Fig. 1 .I). It begins with energy and moisture input and

finally provides the basis and scope for even mathematical modelling. This model

provides conceptual clarity and theoretical background for incorporating process data into

the scheme of land classification. This theoretical framework could be interlinked with

biophysical land classification proposed by Moss (1 975) for Canada, Land System

approach of CSIRO, Australia and Terrain System of ITC, The Netherlands. The units

identified under different morphogenetic processes can be ordered into a hierarchy and

use of data at each level could be indicated (Table 1.1). Human induced changes are

reflected in the landuse pattern of any given area.

( 1 ) (2) (3 (4) ( 5 ) (6) ENVIRON INPUI'S: CONTROL INTEGRATING LAND UNIT PROCESS BASIS AND

MAJOR CONTROLS PROCESSES LANDSCAPE COMPONENTS RESPONSE NATURE OF IJNITS DETERMINATION

- PRIMARY MATHEMATICAL PRODUCITIVITY MODEL

DECAY AND MATHEMATICAL DECOMPOSITION MODEL 1

ENERGY BIOTIC VEGETATION

WATER AND PEDOLOGIC L BUEGET

MOISTURE 1 1 1 HYDROLOGIC

SOIL MOISTURE FLOW 1 OF NUTKI EN'I'S CAI .CUI.ATIONS

SURFACE RUN-OFF

Source: Moss (1 983).

Fig. 1.1 A MODEL TO ILLUSTRATE A METHODOLOGY FOR THE INCORPORATION OF PROCESS DATA INTO LAND CLASSIFICATION

TABLE I .I TERRAIN SYSTEM, PROCESS DATA AND APPLICABILITY

Use of data

Major regional decisions concerning land management

Rankingof potential value for regional decisions, geo-ecologica l evaluation Landuse planning

Soil erosion potentiall critical area assessment

Level of hierarchy Terrain province1 eco-region

Terrain pattern1 Terrain system

Terrain unit/ Land unit/ Ecosection Terrain components1 Ecosite

Process data

Natural vegetation1 Biomass

Pedological processes

Geomorphicl hydrologic processes Natural changes and impacts due to human intervention (anthropogenic processes)

Scale

>1:250,000

1 :250,000

1 :50,000

1:10,000

Environmental value of data Land surface

dynamics (fundamental land1 biotic function controls) Modificationofbasic functions by local controls (soil capability)

Local expression of changes in controls by various processes Site specific information process- response

Due to interlinkage of rnorphogenetic processes, the hnctional changes in human-

environment relationship reflected through landuse pattern trigger a cascading change

from local to global levels, from specific to diffuse and from low complexity to high

complexity. Landuse change takes place at the site level or micro level, whereas, drivers

of landuse change can be either proximate cause or macro level decision or both and

similar is the case with impact of landuse change. The horizontal and vertical linkages of

landuse change, especially in the case of deforestation is given in Fig. 1.2.

Environment Economic Sociat

Source: Gallop in (1 994); Winograd (1 99 7).

Fig. 1.2 VERTICAL AND HORIZONTAL LINKAGES: THE CASE OF LANDUSE

The morphogenetic processes are thus subjected to alteration as a result of landuse

change. Capturing of these changes and study of their impact on landscape form

important research agenda. Many of the landscape studies attempt to concentrate on

interaction of the ecological processes with the environment to create landscape pattem

and influence of these patterns on ecological functions (0 Neillet. al., 1995). There is a

need to develop measures of spatial pattern and to correlate pattem with ecological

processes in micro level study, particularly in today's context of societal quest for

sustainable development.

The present thesis is based on the above conceptual framework. The

morphogenetic processes have been-linked to landuse pattern and geoecological impacts

were assessed. The study framework is given in Fig. 1.3.

/-+ Analysis , Evaluation

\

I I I I

Impact 1 '

Fig. I .3 STUDY FRAMEWORK

1.2 Review of literature

Morphogenetic processes + Geology + Climate + Hydrology + Landfonn + Soil + Vegetation

Study of rnorphogenetic processes had gained importance during the 2nd half of

the last century. Although, the necessity for the study of processes has been felt since the

4

Landuse Load Environmental evaluation

development of the subject, substantive research activities related to processes could be

traced since 1950s (Chorley, Dunn and Beckinsale, 1964, 1973). As early as 1877 Gilbert

wrote about the erosion, weathering, transport, deposition and equilibrium in studying the

geology of Henry Mountain, Utah. Various approaches followed in geomorphology have

been reviewed by Chorley and Kennedy (1971), Dury (1 972), Jennings (1 973), Brown

(1975) and Chorley (1978). All these reviews tried to highlight the development of the

* Deforestation * Soil degradation Jr Sand and clay

mining

Agricultural and other use Change

subject and the main thrust. Development of theory of geomorphology has been

Geoecological impact +3 Landform and landuse Q Landuse, water quality and hydrogeochemistry +3 Landuse and demography

* Demography Jr Occupation

envisaged through a number of phases from teleological to taxonomic to functional

(Chorley, 1978). Derbyshire et. al. (1979) attempted to provide an introduction to

geomorphological processes and their operation procedure.

Process studies have progressed in four ways (Selby, 1985): These are: (i)

detailed measurements both in the field and laboratory based firmly on physical sciences,

(ii) use of statistical techniques and rigorous measurement, (iii) availability of large

volume of data and computer application and (iv) enlarged scope of work due to

availability of fund and trained manpower. Recent improvement of knowledge covering

the aspects of rate, mechanism, models and application has added impetus to geomorphic

research related to processes.

German and French geomorphologists had drawn attention in incorporating

climatic variables in geomorphic studies. The branch of climatic geomorphology has

been evolved in these processes. Budel (1977) contented that exogenous processes, in

their climatic variation, create the morphological picture of the earth, while geological

structures and tectonics merely influence and modify local landform (Selby, 1 985).

Identification of morphogenetic regions associated with dominant processes and climatic

variables was attempted way back in 1950 by Peltier (1950) in a global scale. This

approach could not take note of the periodicity of geomorphic processes in relation to

climatic seasonality, role of vegetation and soil and impact of anthropogenic intervention

in modifying the landcover. However, subsequent developments in climatic

geomorphology have tried to address the role of vegetation and soil. Climatic

geomorphology indeed must examine the interactions between all the factors influencing

the processes covering geologic structure, climate with seasonal variability, vegetation

and soil (Tricart and Cailleux, 1972). Geographers of Soviet Union and other East

European Countries have contributed significantly in furthering process studies in

geography. Works of Isachenko (1 973), Prokayev (1 962), Starkel (1 976), among others,

are noteworthy.

Study of landscape evolution depends on understanding the present spatial

distribution of processes and process rate, linkage between erosional and depositional

component, comparison of spatial versus temporal change and appraisal of stratigraphic

record. The Binghamton symposia concentrated on "Space and Time in Geomorphology"

to cover these issues (Thorn et. al, 1982). Significance of the process studies, as Johnson

(1 9 82) pointed out is "in understanding the mechanics and control of geomorp hic

processes and short-term variability and behaviour of geomorphic systems and

land forms".

Response of the processes can be captured spatially by identifying different

landform or terrain units. Since Mabbutt's (1968) and Gardiner's (1976) emphasis on

land as an end product of complex ecological interactions, there have been various

approaches proposed from time to time. Moss (1981, 1983) proposed land classification

methods by incorporating process data. The Land System approach by CSIRO, Australia

and the Terrain System approach by ITC, The Netherlands attempted to classify land

following landscape approach incorporating geomorphic processes (Meij erink, 1 98 8,

Chattopadhyay and Mahamaya, 1995).

As process study is related to dynamic/ system approach, it is necessary to

investigate within a framework of a river basin, which collect, concentrate and coordinate

the movement of water and sediment. Gregory (1976) reviewed the drainage basin

studies since 1700 and identified seven approaches: Morphometry (spatial and topology),

Basin characteristics, Channel pattern, Channel geometry, Theory, Dynamics and Palaeo

studies. From Horton's (1945) morphometric analysis to Chorley (1962), Schumm's

(1 977) emphasis on palaeohydrology and metamorphosis of rivers and river channels, the

primary concern is to understand the process variation in water and sediment production

over time and effect of processes over landforms at present, in the past and also in the

future. Recent attention has been drawn to the applied studies.

During 1970s greater emphasis was given for a more integrated approach to

environmental problems and in subsequent three decades research agenda changed at

various levels. Environmental impact assessment, sustainability and sustainable

development become part of the common usage not only in research parlance but also in

general society. Spatial heterogeneity and pattern observed in the field are recognised as

important landscape components and not averaged across the space. Site-specific

intervention of human being on the terrestrial biosphere creates a mosaic of Landuses that

tend to threaten the basic mosaic of the intact ecosystems on intact landscapes (0 Neill,

et. a[., 1995). In a review article Stuart Chapin et. al. (2000) observed that "landuse

change is projected to have the largest global impact on biodiversity by the year 2100

followed by climate change, nitrogen deposition, species introduction and changing

concentration of atmospheric COz". Studies on landuse and landuse changes are not only

gaining more and more importance but also becoming the focus of mu1 ti-disciplinary

studies covering a host of issues related to drivers as well as consequence of change.

Turner (1 999) proposed merger of local and regional analyses of landuse changes

because regional and local processes are highly interconnected. Butte1 and Taylor (1994)

made similar observations in their studies on environmental sociology and global

environmental change. Walker and Solecki (1 999) pointed out that land conversion (local

issue) often becomes a serious environmental issue at the regional scale involving

regional ecosystems. Blakie (1 989) highlighted the relation between land degradation

and landuse at the local level. He pointed out the emphasis in the classic approach on

environmental problems leading to environmental solution and on the 'ignorance' of land

users.

Several studies on landuse have been attempted in India at different levels. Most

of the works were initiated following Dudly Stamp's landuse survey of U.K. in the

beginning of 1940s. It was at the 1940 session of the Indian Science Congress held at

Madras that Prof. S .P .Chatterj ee pointed out the necessity of undertaking the landuse

survey in Tndia on the lines of the landuse survey of Great Bretain. He published a report

on "Land utilization in the District of 24 Parganas, Bengal" in 1945. Dayal (1947)

prepared a thesis on agricultural geography of Bihar. He discussed the influence of soils

and climatic elements on land utilization, the pressure of population on land and the

nature of land utilization. Chattejee (1952) undertook more detailed land utilization

survey in Howrah district and 1200 landuse maps at the scale of 1 :3960 covering 813

villages were prepared. Rao (1947) has emphasized the techniques of soil survey for

analysis of landuse in the Godavari region. Roy (1 968) documented rural landuse pattem

in Azamgarh. Singh (1971) dealt with the optimum carrying capacity of the land in

Punjab. Deshmukh (1 975) studied rural landuse of Lonkhede. Models in land utilization

were documented by Mandal(1980). Sustainable development initiative was documented

by Singh (1996). Planning for sustainability on natural resources and bio-energy was

attempted by Maheshwari et, al. (1996). There had been a change in landuse studies in

India, from mere documentation of changes the attempt is now to investigate the cause

and consequences of landuse change. Advent of Remote Sensing and Geographic

Information System (GIs) have facilitated time-series and multi-variable analysis.

Chattopadhyay (1 9 85) studied deforestation in Keral a and attempted to highlight the

related issues. George and Chattopadhyay (2001) analysed the landuse in Kerala in

relation to population pressure.

Biophysical land classification for the State of Kerala was attempted by

Chattopadhyay and Mahamaya (1998) in order to design sustainable landuse pattem.

Maharnaya (1 998) attempted geomorphic analysis for sustainable landuse development in

a small drainage basin of south Kerala. The thrust of the paper was to link potential

landuse with land units identified based on processes.

River basins are considered as natural integrators of the effects of many natural

and anthropogenic inputs and anthropogenic interventions. Water quality parameters are

determined and hydrogeochemical investigations of rivers, water bodies and oceans have

become important tools to evaluate the environmental degradation of catchments for

identification of sources of pollution. Major scientific concern about global river quality

dates back from the 1950's when the International Association for Scientific Hydrology

launched a world-wide programme for the first time (Durum, et. nl., 1960). This work

was one of the databases of Livingstone (1963), a master-work on river chemistry which

still constitutes the only available thesaurus at global scale. Meybeck and Helrner (1989)

did the monitoring of river quality of pristine stage to global pollution. Meybeck (1998)

studied man and river interface, its multiple impacts on the Seine river basin.

Biogeochemistry of major African rivers was documented by Martin and Probst (1991).

Further, Meybeck (200 1 ) worked on global alteration of riverine geochemistry through

anthropogenic interventions.

In India, Agarwal and his team (1976) assessed water quality parameters

(physico-chemical) of the Ganges at Varanasi. Chandrasekhara Chetty (1 978)

documented utility aspects of river waters affected by saline incursion in Goa.

Subramanian (1 979) generated hydrogeochemical data sets for the major drainage basins

of India. Varshney (1981) worked on water pollution and management reviews, Trivedi

(1988) generated data sets on ecology and pollution of Indian rivers. Venkateswarlu and

Sarnpathkurnar (1982) made chemical and biological assessment of pollution in river

Moosi, Hyderabad. Systematic hydrogeochemical investigations have been initiated in

Kerala with the pioneering work on Killi Ar (river) (CESS Report, 1995, 1996).

Mahamaya el. al. (1 996, 1997) documented results and generated data on Killi Ar (river).

Human impact on the biogeochemistry of rives has been studied by Ittekkot and

Subramanian (1 999). Dekhov et. al., 1 999 has documented chemical composition of

riverine suspended matter and sediments from the Indian sub-continent. Suresh (1 999)

has studied impact of urbanisation on quality of groundwater regime. Status of riverine

pollution in south Kerala and its relation to physiography and landuse have been

documented by Soman, et. al. (1997,2002).

This brief general review of literature has brought out that there were several

topical studies attempted at di fferent levels but few studies tried to link rnorphogenic

processes with landuse within a larger fiame of analysis, evaluation and impact studies.

1.3 Objectives

The study on Ittikara river basin has been undertaken with the following precise

objectives:

a. In-depth analysis of the morphogenetic processes operative in the Ittikara basin

including elucidation of the role of geology and structure on landforms,

morphometric analysis of surface drainage, landform analysis covering slope form

and profile analysis, and finally identification of morphogenetic regions,

b. Detailed analysis of the landuse pattem and its changing trend over the years,

c. Assessment of human resources and importance of demographic parameters in

altering physical processes,

d. Evaluation of major environmental issues, especially problems of deforestation, soil

degradation, sand and clay mining as contributors to changes in riverine ecology, and

analysis of hydrogeochemistry and environmental biogeochemistry as indicators of

water quality and onland changes,

e. Impact assessment of morphogenetic processes on landuse pattem and 1 'ce versa,

impact analysis of landuse pattern on water quality, interrelation of landuse pattern

and demography, and

f. Application of Geographic Information System (GIs) for understanding the

geoecological impact.

1.4 Study area

The Ittikara drainage basin occupies the southern sector of Kollam and a small

portion of Thiruvananthapuram districts and it extends from 8" 44 10 N to 9' 0 50 N

latitudes and 76" 37 E to 77' 2 20 E longitudesl'he river Ittikara originates from the

low hills of Karakumu (250 metre above Mean Sea Level) adjacent to Madathara in the

foothill region of the Westcm Ghats and flows through the Yeroor Reserved Forest area

in a straight north-westerly course where streams of various orders are formed and join

the main river (Fig. 1 -4). After flowing over the midland terrain river Tttikara debouches

LOCATION MAP IlTlKARA DRAINAGE BASIN

D 5- - I

INDEX Roed cr--H Railway W- Stream ------- k b l d bwndary

I

Fig. 1.4 I I I

into the Paravur Kayal north of Paravur in the south-western portion of Kollam district

(Fig. 1.5). The river Ittikara is a west-flowing stream. The river has a length of 56 km out

of which 16 km stretch is considered for navigation in the downstream section.

Catchment area of the basin is 650 km2. The length of :he coastline forming the western

boundary of the study area is 9.50 lan. The basin comes under the realm of tropical dry-

wet climate. Ittikara basin encompasses 7 blocks covering 32 panchayats and one

municipality (Fig. 1.6).

Before discussing characteristics of the study area surface and groundwater

conditions are discussed here briefly in order to provide the background information. The

total surface water potential in the Ittikara basin has been computed to be 446 MCM

(CGWB, 1987). Monthly discharge varies from 1972 to 1992 (Appendix I). Around

7.1% of the annual rainfall drains out as base flow in the basin, however, it records

spatial variation depending on terrain type, soil, landuse and management practices. Base

flow contribution derived from data obtained fiom Ayur gauging station for the period of

1972 to 1992 is determined to be 14.5% of the annual run-off. The annual percentages of

base flow varied between 2.7% and 19.9% of the annual run-off. With the available

limited data, water table contour map has been prepared for Ittikara basin (Fig. 1.7). It

was based on water-level measurements in the wells for the pre-monsoon, 1994.

Contours could not be drawn in the upland portion of the basin due to non-availability of

data. Water table of the basin is controlled by its physiography, geological formations,

extent of weathering of rocks, rainfall and vegetation cover. Water table contour pattern

tends to follow the contours of the overlying ground surface, although in a more subdued

form. Water table contour map shows that the general flow of groundwater is towards

west.

Geologic and geomorphic setting and structural features of the area under normal

conditions of precipitation control the occurrence and movement of groundwater.

Continuity, thickness and aquifer characteristics of the strata determine the groundwater

storage potential (CESS Report, 2001). In order to assess the groundwater potential of the

Ittikara basin hydrogeology map was prepared (Fig. 1.8). Along with lithologic features,

DRA l NAGE ITTIKARA BASIN

I

I I Fig. 1.5

ADMINISTRATIVE MAP ITTIKARA DRAINAGE BASIN

1 0 I 2 h -

Legend O D i s l r i c l Boundary

Block Bol~ndary Panohayat Boundary Road Rnl lway

-10- Contour (m) (above MSL)

NA Dala not available Sourn: year 1994. R-onn

WATER TABLE CONTOUR ITlKARA DRAINAGE BASIN

D 5Kms

HYDROGEOLOGY IlTlKARA DRAINAGE BASIN

0 5 h

u rkm.~ AGE INTRUSIVES

Recant # Area suhble for grnund

SIhb and d ~ p d]olnI water dmloprnenl wilh a thick zone of latent0 I mlley fill

Lateli. P l e ~ ~ t ~ c e n e --._ . . Major fault zone

-+ C - Araa s u W c Lor groundmter M~owne ~ a b w w l b p o ~ m Gama - blots. gneiss t + Alarmn Archasan

Khondallte ---. Ummant Gatrce CGWB 1087

Fig. 1.8

structural and terrain details were also considered for evaluating the water resource

potential. Areal spread of lithological units show that hard crystalline rocks comprising

khondalites, garnet-biotite gneisses and the intrusives occupy about 45% of the study

area. Groundwater potential in this zone is relatively low. Towards west, rolling terrain

with laterite formation has better groundwater potential. Coastal sedimentary beds show

good groundwater prospect.

The Ittikara basin displays unique physical diversity ranging from wide coastal

plain and low-lying lands in the west to dissected midland and highlands of the Western

Ghats in the east. The major landuse category in the basin is settlement with mixed tree

crops. Recent landuse survey reveals that a considerable portion of the area under mixed

tree crops and forest are converted into rubber and plantation crops. The water resource

of the basin is assessed as 429 ~ r n ~ . The wetlands of the basin, according to the PWD

(1 974) estimate require 343 ~ r n ) of water for imgating three paddy crops and 50% of

gardenlands need 123 ~ r n ~ of water. At present, no major irrigation scheme is in

operation. However, the Kallada Irrigation Project is supposed to imgate an area of 152

km2 of the basin. Irrigation facilities are provided by a few lift and minor imgation

schemes at present. Detailed investigations are being carried out for the Ittikara River

Valley scheme for examining the scope for irrigating the lands to the right bank of the

Ittikara river which are not covered by the Kallada Project and those to the right bank of

the Varnanapuram river. In addition to these, there lies the scope for construction of a

number of subsidiary storage across the river in its upper reaches.

Eravipuram panchayat of Mukhathala block recorded the highest population

density of 5533 personsflanL whereas Kulathupuzha panchayat of Anchal block had a

population density of 78 persons/krn2 according to 1991 census. The basin area has well

connected road networks. According to the Department of Economics and Statistics,

1996, the National Highway has 25 km, coverage within two panchayats and 66 km of

State Highway falls within seven blocks encompassing the study area (Appendix 2).

Other than these, Main District Roads (MDR) owned by FWD, Kerala and panchayat

roads are also well maintained.

1.5 Methodology and data source

In order to pursue the study proposed here, qualitative and quantitative analyses

of a large number of parameters covering biophysical, landuse, and demographic

characteristics are envisaged. The methodology will address the issues related to

morphogenesis and interrelated aspects like terrain pattern, geoecology and

environmental evaluation. An effort has been made to establish causal relationship among

apparently independent factors. Methodology adopted included primary data collection,

field mapping, map analysis in laboratory with the help of topographic sheets of

1 :250,000 and 1 :50,000 scales, secondary data collection from various departments and

computer application in data assimilation and display. Analyses of physical factors and

landuse mapping on macro scale as well as in micro scale have been taken up. Analysis

and mapping have been done for the Ittikara basin as a whole and for its three important

sub-basins, eg. Palliman Ar., Kulanji Thodu (stream) and Man Ar which are situated on

three different physiographic units. Geographic Information System (GIs) are a useful

and perhaps necessary tool for incorporating environmental indicators into the

development process. As the data really represents actual-ground condition and can be

transformed and manipulated interactively in a GIs, they can serve as a test bed for

understanding the environmental processes or for analysing the results or trends or for

anticipating the possible results of planning decision (Burrough, 1986).

The geological map has been prepared by assimilating data from existing

geological maps. The lineament map was prepared by deciphering data from IRS image

in 1 :50,000 scale.

Morp hometric analyses or quantitative geomorphology of drainage basins and

channel networks were taken up to understand river geometry. This section treats

quantitative landform analysis as it applies to normally developed watersheds in which

running water and associated mass gravity movements, acting over long period of time,

are the chief agents in developing surface geometry. Emphasis is upon the geometry

itself, rather than upon the dynamic processes of erosion and transportation which shape

the forms (Strahler, 1964). Linear aspects of the channel system, areal aspects of drainage

basin and relief aspect of drainage basin have been attempted in order to appraise the

channel morphometry and to understand the denudational processes operative in various

parts of the basin.

In evaluating terrain, the classification system must begin with the "main origin",

the dominant process currently operative. Under each of these dominant processes or

specific origin a number of sub-units have been identified which has formed the base of

morphogenetic regions. Geomorphological mapping has been done based on

identification of terrain units by landscape approach propagated by International Institute

for Aerospace Survey and Earth Sciences (ITC), the Netherlands (Verstappen and Van

Zuidam, 1968) and as adopted for Kerala by Chattopadhyay and Mahamaya (1995). It

was based on experience in the use of the then known geomorphologic systems and

legends used for map-making of various parts of the world. The ITC methods were

modified and developed further and it became a true mapping system with distinct

characteristics. Three main approaches can be recognized which have been considered in

designing such a system; these are:

1. the genetic approach

2. the landscape approach

3. the parametric approach

In the genetic approach, much attention is given to geologic aspects and

geomorphologic processes, with little attention to landforms. The landscape approach can

be further modified if it is based on landform, lithology and genesis. The landform

characterises the landscape quite well. They are recognized with ease both in the field as

well as from image and can easily be grouped into systems or sub-divided into

components. Another advantage of this approach is that the units can be grouped into

higher order or can be sub-divided into lower order depending upon the number of

variables considered. The parametric approach refers to the terrain classification on the

basis of selected attributes like slope, altitude etc. It provides a quantitative fiamework

for an otherwise qualitative or descriptive map.

Table 1.2 modified and adopted from Babiker (1 977) provides a comparative

statement of important characteristics of different approaches:

TABLE I .2 TERRAIN CLASSIFICATION APPROACHES

I Characteristics I Genetic approach I Landscape approach I Parametric approach I

Reconnaissance survey

Semi-detailed survey

Unit dimension

Boundary

Homogeneity of units

Field identification of units

Time duration for survey

Possible

Not Applicable

Large Units

Vague

Not possible

Difficult

Limited, mainly academic

Short

Possible

Possible

Medium to small size

Clear

Possible

Easy

Planning Oriented

Short

Difficult

Possible

Small

Vague

Possible in terms of single parameter

Difficult

Limited

Long

Although, there are differences among these approaches, it is important to

consider them as complimentary. A combined approach provides significant results

particularly where the purpose is application oriented. It is possible to consider genetic

data, landform attributes and specific parametric data for the units depending upon the

need or planning requirement. It is possible to establish hierarchical classification system

for terrain analysis by involving more and more parameters at different levels. The

classification process begins with geomorphologic origin followed by specific origin,

lithology, morphometry (relief, valley density, slope form) and finally incorporating

soillcatena information, sequence can be established. Table 1.3 is compiled to show the

hierarchical classification system followed in various countr~eslinstitutions. It is evident

from this Table 1.3 that there is a similarity of thought about the occurrence of

identifiable units of landscape, which can be arranged into a hierarchical order.

TABLE 1.3 HIERARCHICAL CLASSIFICATION SYSTEM

The terrain classif cation scheme adopted for Ittikara basin is landscape approach

based on a scale of 1 :50,000 and incorporates data related to all aspects of morphologic

processes, rnorphometry, soil and landuse. This scheme partly draws from the ITC

system of geornorphologic mapping. The classification scheme adopted here follows the

principle of hierarchy theory (Haigh, 1987). A 4-order classification system has been

built-up (Fig. 1.9). Each order is so defined that the units are mutually exclusive with a

specific generic concepts and a lower order unit represents a sub-order of the immediate

higher order unit. The higher order units (1'' and 2" order) have been identified using the

existing body of knowledge. The 3" order categories, i . ~ . the terrain units have been

demarcated from the landsat data products, whereas the 4th order categories were

identified from PAN image analysis and through field mapping.

Level

I

I I

I I I

IV

-

Scale

I :250,000

1 :250,000

I : 50,000

1 :I 0,000

CSlRO Australia

Terrain Province/ Complex land system

Terrain pattern/ Land system

Terrain unitlland unit

Terrain compo- nentlsite

Bio-physical (Canada)

Eco areal Eco region

Eco zone Ecodistrict

Eco section

Ecosite

Oxford MEXE

Land region

Land System

Land facet

Land element

ITC (Nether- lands)

Terrain Province

Terrain system (pattern)

Terrain Unit

Terrain compo- nent

Physio graphic

Physiogra- phic province

Main physiogra- phic unit

Detailed physio graphic unit

P hysio graphic element

Germany

Macro- chore

Mesochore

Microchore

Eco-tope complex

Soviet Union

Lands- cape mestnest

Urochi- sche

Urochi- scha

Facies

'

ATTRIBUTE LEVEL SAMPLE TYPE

I Climate 1

Physiography r 1 ~rocess-1

Lithology

Terrain province level- 1

Western Ghats1 Upland

I I

Structure

Landform i h

Erosional state

Terrain system level-ll

-

Accretionall Erosional units

Morphograp hy

Fig. 1.9 THE SCHEME OF TERRAIN CLASSIFICATION

Terrain component Geoforrn level-IV

Mapping has been done in 1 :50,000 scale by using topographical maps and in

1:25,000 scale extracting data from PAN image (IRS IC, 1999) for selected sub-basins.

--

Valley floor1 Levee

Slope maps of selected three sub-basins of Ittikara Ar have been prepared by

dividing the area in 0.25 km2 grid and computing the average slope for each grid by

taking into account the lowest and the highest altitude and distance between these two

points within the concerned grid (Chattopadhyay and Mahamaya, 1995).

The importance of hydrology in the assessment, development, utilisation and

management of the water resources of 'any region is being increasingly realised at all

levels (Raghunath, 1985). Rainfall data analyses have been done with the available data.

The river is being gauged at Ayur and Ittikara. However, the available discharge data are

I

Terrain component level-Ill

-

Floodplain1 Beach

not suficient for any correlation study. Hydrogeological map has been prepared along

with the water table contour map. Well depths were monitored for this purpose with

supplementary data obtained from the Central Ground Water Board.

Landuse bears a close correspondence with the terrain characteristics, especially

in the tropical countries, where agriculture is much akin to the natural ecosystem

(Mahamaya and Sakunthala, 1987). The study envisages to characterize landuse units in

relation to land system units and in turn to assess the land potential for better

management. Landuse map for the Ittikara basin has been prepared in 1:50,000 scale

using topographical maps and IRS image. Three sub-basins of Ittikara river covering 48 %

of the basinal area have been taken up for detailed analysis. Data have been extracted

from PAN image (IRS IC, 1999). The principle of visual interpretation of satellite image

is followed. As a first step image characteristics are translated into land management

attributes. The translation process (transfer function) is guided by local knowledge (eg.

soil, geologic or landuse maps; reports or agricultural statistics), which can be gathered

during fieldwork or through background studies. In the next step polygons are drawn

around features (fields, land units, homogeneous areas with natural vegetation, settlement

etc.) and a label referenced to tables is assigned to each polygon characterizing it by

attributes (the legend). Image characteristics can be pattern, texture; colours or tones on

the image; or the changing colour during a growing season (Bronsveld et. al., 1994).

These were subjected to detailed field verifications. Time-series landuse maps were

prepared to detect changes oveL the years. Accurate up-to-date information is of critical

importance for land management. Data on changing conditions are needed continually to

detect problems, plan activities and predict and monitor results of activities.

Agriculture is the prime occupation of the people of this basin. Crop statistics for

the period of 1996 for Kollam and Thiruvananthapuram districts were collected from the

State Planning Board, Government of Kerala, Thiruvananthapuram. Crop combinat ion

method proposed by Weaver (1954) has been used to indicate dominance of crop

practices at panchayat level. The details of the method are given in Appendix 3.

Analyses of demographic parameters were based primarily on 1991 census data.

Decadal growth of population, and population density have been calculated for each

panchayat. Occupational structure of the populace has been dealt with.

The chapter on environmental evaluation is based mainly on primary data and

observations. Secondary data were also used to supplement the findings. Extent and

depletion of forest coverage have been marked from satellite image of 1999. Estimate on

sand and clay mining were based on primary data. Hydrogeochemical analysis and study

on environmental biogeochemistry were conducted through primary s w e y . 17 sampling

stations were selected based on a combination of physiography, drainage and landuse

parameters. Water samples were collected and they were analysed for physico-chemical

and microbiological parameters in the Chemical laboratory of the Centre for Earth

Science Studies. Biogeochemical samples were analysed at the Institute of

Biogeochemistry and Marine Chemistry, University of Hamburg and at the Center for

Tropical Marine Ecology (ZMT), Bremen, Germany.

Geoecological impact assessment aims at identifying the consequences for the

biogeophysical environment and for man's health and welfare of implementing particular

activities (Michele et. nl., 1995). Geographic Information System (GIs) is a useful and

perhaps necessary tool for incorporating environmental indicators into the developmental

process. The integration of economic, social and environmental indicators in a spatial

framework allow for more powerful and realistic analyses than those offered by

conventional non-spatial methods (Wingrad and Eade, 1997). GIs based overlay analysis

and modelling are extremely useful for aiding our understanding of environmental

systems and helping in management decision making. Integration of data on landform,

landuse and water quality was possible through application of GIs. Thematic maps on

landform, landuse, relief, drainage, drainage density, population density along with their

attributes were integrated using PC ARC/INFO and PC TIN softwares. 3-D modelling

was accomplished from the 20 m-interval contour map of the study area (part). This is a

representation of a surface derived from irregularly spaced sample points and break line

features. Each sample point has an X, Y coordinate and a surface of Z value. These points

are connected by edges to form a set of non-overlapping triangles that can be used to

model the surface (PC ARCtINFO, 1995). Thus digital terrain model (DTM) for a sub-

basin has been created by regular array of Z value, referenced to a common datum which

represents terrain relief. Overlay analysis is also done to ascertain the interconnectivity.

Spatial and seasonal variations of DO, BOD and FC are shown through GIs analysis. The

sampling stations along the main and tributary streams were digitized. DO values for

different sampling seasons were marked by attributing class interval and linear influence

of the sampling stations as emerged from the analytical results (CESS Report, 1996).

Product moment correlation coefficient has been worked out based on the indices value

calculated for each panchayat in order to understand the spatial association and

intercorrelations among population, landuse and gross cropped area of panchayats.

1.6 Hypothesis

Following hypotheses related to objectives for the study on Ittikara river basin

have been cited. An attempt has been taken to establish the hypotheses regarding

morphogenesis and landuse and vice versa, in the following chapters. The hypotheses are

as follows:

* Terrain condition is a determinant of landuse pattern

Landuse pattem is primarily governed by the terrain condition. The physiography-soil-

matrix exerts pronounced influence on landuse pattern as is explicit in the State of

Kerala. It is intended to test this observation under this hypothesis.

* Landuse/landcover alterations impact landscape type

Landscape types are modified by landusel landcover changes. When wetlands are

diverted to garden lands and to accommodate settlement, the local slope condition,

surface run-off and infiltration rate etc are modified. This hypothesis attempts to

highlight this issue.

* Spatial variations in landuse pattern influences water quality

Drainage discharges, both quality and quantities are influenced by rainfall, terrain type,

soil, geology and landuselland cover. Given a uniform rainfall pattern soil, ten-ain and

geologic condition, it is the landusel landcover that affects the drainage discharge pattern.

It is necessary to study the spatial variability of landuse and water quality parameters to

capture this impact. This hypothesis is designed to test this interrelationship.

* Landuse and landscape alterations affect biogeochemical cycling.

Alterations of landuse and landscape, although occur locally, have long- range impact on

biogeochemical cycles as they affect the water system through which the cycles are

linked. This hypothesis will posit the study in a larger fi-ame.

1.7 Expected contribution of the thesis

This thesis is expected to contribute in understanding the overall environmental

condition of the basin especifically in the realm of the following five issues: 1)

deciphering the responses of natural systems to environmental changes; especially in the

realm of landusel landcover changes and their responses on the landscape as well in the

aquatic system, 2) integration of environmental parameters into landuse planning and

management, 3) geoecological impact assessment of activities that can affect land-water

systems through RS-GIs application, 4) definition and listing of indicators that can be

used to assess different impacts, and 5) design of remedial actions.

Geomorphologic indicators, measured successively over time, are expected to

describe trends in the conditions of phenomena, systems, resources or assets.

Goemorphologic indices can help in assessing the impact of human activities, for

example on sediment transport and erosion processes, and the degree to which these

processes interfere with human activities (Rix, 1995). Reconsideration of earth science

education was proposed by Fabbri and Cendrero (1 995) in view of research contribution

in problem identification and problem solving.

In this context the present thesis will have a long-term contribution. As the

framework of this thesis is multi-disciplinary, it is expected to enrich the roots of Earth

Science education. ,

1.8 Arrangement/ Organisation of the thesis

The integrated structure of the many different components in the complex array of

morphogenetic analysis and its impact on landuse pattem as well as geoecological

assessment make it difficult to compartmentalize the material. A division of these

materials into seven large parts, however, provides a logical and convenient form for

analysis.

Chapter I- Introduction: This chapter provides a synopsis for the thesis and sets the stage

for the types of problems and for the considerations that are necessary for their solution.

This chapter introduces the topic in Kerala's context, its purpose and broad aim and its

linkage to larger issue. Literature review, methodology of the work and hypotheses have

been dealt in separate sub-chapters.

Chapter 11- Analysis of Morphogenetic Processes: This chapter deals mainly with the

analyses of morphogenetic processes highlighting on morphometric analysis of river

Ittikara, slope profile, landform and identification of morphogenetic regions and it is

discussed under appropriate separate sub-headings .

Chapter III- Londuse: Analysis of landuse pattern is of ovemding importance in the

context of physical and environmental resource assessment and it is dealt in separate sub-

headings. Landuse pattern of the total basin as well as of three sub-basins- Palliman Ar,

Kulanji Thodu and Man Ar have been discussed in detail. Time-series landuse mapping

of these sub-basins occupy an important part within this chapter. Cropping pattem along

with crop combination within the basin area have been dealt with.

Chapter IV- Demography: Demographic pattern of the basin area emphasizing on

population density distribution and decadal growth has been discussed in this Chapter IV.

Description of occupational structure of the working population is provided under various

headings.

Chapter V- Environmental Evaluation: This chapter deals with deforestation, soil

degradation, hydrogeochernistry, environmental biogeochemistry, groundwater quality

and sand and clay mining. A sample survey on critical area analysis is also included.

Chapter VI- Geoecological Impact Assessment: This chapter puts forward geoecological

impact assessment derived from parametric analyses and deductions of hypotheses

discussed in proceeding chapters. Impact of landuse changes on water quality as well as

on population density and impact of landform on setting landuse pattern have been

discussed under separate sub-headings.

Chapter VII- Conclusion: The concluding chapter advances the major findings of the

study after analytically evaluating adoption of methodology and data source. Limitations

felt on the methodology and data source have also been recorded. Finally, the study

concludes by suggesting remedial measures for improving the situation faced by

environmental as well as by anthropogenic dimensions.