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Water for Balochistan Policy Briefings Volume (4), No. 8, 2008

TA-4560 (PAK) Project for “Supporting Implementation of IWRM Policy in Balochistan” – Government of Balochistan - ADB and Royal Government of Netherlands

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Potential Recharge Zones of Over-drawn River Basins of Balochistan, Pakistan

Mohammad Riaz, Babar Sani 1, Kamran Babar2 and Dr. Shahid Ahmad3

1 Study Consultants, Package Assignment, TA-4560 (PAK), Supporting Public Resource Management in Balochistan, Halcorw Pakistan and Cameos Consultant, Quetta 2 Team Leader of Package Assignment, TA-4560 (PAK), Supporting Public Resource Management in Balochistan, Halcorw Pakistan and Cameos Consultant, Quetta 3 Project Coordinator, TA-4560 (PAK), Supporting Public Resource Management in Balochistan, Asian Development Bank.



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Potential Recharge Zones of Over-drawn River Basins of Balochistan, Pakistan

Mohammad Riaz, Babar Sani 4, Kamran Babar5 and Dr. Shahid Ahmad6

1. Background and Context of the Study 1.1. Current State of Water Resources in Balochistan

Balochistan province of Pakistan suffers from water scarcity with extensive spatial and temporal variability in precipitation. Storage and recharge are two major components of groundwater aquifer. Safe yield is generally considered equivalent to the average annual recharge to a river basin but it is not possible to adhere to this concept in the arid regions to meet water demand during persistent droughts. Electrification in Balochistan started in early 70s and contributed in lowering of water table and mining of groundwater. Subsidy on electric tariff for tubewells has further aggravated the groundwater mining. As a result, majority of the 18 basins are in deficit (Figure 1). The over-drawn river basins are: Pishin-Lora, Nari and Zhob. Pishin-Lora is the most over-drawn basin. Floodwater availability in these basins is significant yet major portion of it is lost as runoff. The net balance of annual surface water available is 0.133, 0.691 and 0.157 billion m3 for Pishin-Lora, Nari and Zhob river basins, respectively. The average annual recharge to groundwater in these basins is 0.170, 0.160 and 0.270 billion m3 and net deficit of -0.396 and -0.110 billion m3 for Pishin-Lora and Zhob basins, respectively and 0.090 billion m3 for the Nari basin. Figure 1. River basins of Balochistan 1.2. Study Target Area – Three Over-drawn Basins The IWRM Policy of Balochistan 2006 highlighted the need to initiate a study to identify potential recharge zones (PRZs) for the three over-drawn basins, which was undertaken in the ADB TA Grant Project jointly by the M/S Halcrow Pakistan and Cameos Consultants, Quetta (Figure 2). 1.2.1. Pishin-Lora Basin Pishin-Lora basin lies in the northern part of Balochistan between latitudes 28o 43’ and 31o 00’N and longitudes 66o 12’ and 67o 43’E. Population was 2.179 millions in 1998, of which about 45% lived in Quetta city and 31% in Pishin. Projected population7 of the basin for 2007 is 2.707 millions. The main livelihood sources are: agriculture; livestock; forestry; cottage industry and handicrafts. 4 Study Consultants, Package Assignment, TA-4560 (PAK), Supporting Public Resource Management in Balochistan, Halcorw Pakistan and Cameos Consultant, Quetta 5 Team Leader of Package Assignment, TA-4560 (PAK), Supporting Public Resource Management in Balochistan, Halcorw Pakistan and Cameos Consultant, Quetta 6 Project Coordinator, TA-4560 (PAK), Supporting Public Resource Management in Balochistan, Asian Development Bank. 7 Study entitled “Environmental Flows for Major River Basins of Balochistan” conducted under ADB TA Grant Project



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The basin catchment area is 18,133 Km2, out of which alluvium occupies about 7,873 Km2. It is further sub-divided into eleven sub-basins; Pishin, Kuchlagh, Quetta, Kolpur Sardar Khel, Mastung, Shirinab, Patki, Shahnawaz, Mangochar, Kalat and Kapoto. The main streams are Shore Rud, Bostan-Lora and Pishin-Lora. The Shore Rud drains the southern part of the basin (Kalat, Mastung and Shirinab), the Bostan-Lora drains the south-eastern part (Kolpur, Quetta and Kuchlag) and the Pishin-Lora drains the northern part (Gulistan, Qila Abdullah, Shadizai etc). The climate is arid temperate with low winter precipitation and higher evapotranspiration in summer. The mean annual precipitation is 218 mm and it mainly falls during January to March. The soils are of alluvial origin and suitable for growing high value crops and deciduous fruits. Figure 2. Three overdrawn basins of Balochistan 1.2.2. Nari River Basin Nari basin lies in the northern part of Balochistan between latitudes 290 40’ and 310 00’ N and longitudes 670

10’ and 690 45’E. Population of the basin was 284,230 in 1998 and is projected to be 353,100 in 2007. Catchment area of the basin is 22,298 Km2 out of which 6,680 is covered by alluvium. The basin is divided into 11 sub-basins: Anambar Rud, Beiji River, Dabbar Rud, Dukki, Gumbaz, Harnai, Kahar Rud, Lakhi Rud, Loralai, Mara Rud, Sangan Rud, Sehan Rud, and Ziarat. Most of the streams are ephemeral in nature but there are perennial flows in Loralai River, Sehan Rud, Anambar Rud and Khost River. The base flow in Nari River when it leaves the basin ranges from 89 to 107 million m3. The principal stream is the Nari River and is formed with the confluence of Loralai, Beiji and Khost rivers. Overall surface flows follow the north-south path with some local changes. The mean annual precipitation is 274 mm. 1.2.3. Zhob River Basin Zhob River Basin lies in the northern part of Balochistan, between latitudes 300 30’ and 31030’N and longitudes 67030’ and 69045’E. Population of the basin was 82,903 in 1998 and is projected to be 102,991 in 2007 and is engaged in agriculture, livestock and handicrafts for livelihoods. Catchment area of the basin is 16,425 Km2, out of which 3,975 Km2 is underlain by alluvium. The basin is divided into six sub-basins namely Muslim Bagh, Qila Saifullah, Zhob, Murgha Faqir Zai, and Sharan Jogizai. Some of the larger streams are perennial in short stretches. These include the Faqirzai Rud in the Murgha Faqirzai sub-basin, the Kano River in the Muslim Bagh sub-basin and the Sawar Rud and Toiwar (Kandil) Rud in the Qila Saifullah sub-basin. The Zhob River itself is perennial in two stretches, from just north of Qila Saifullah (Qila Tehmur) for approximately 54 kms eastward, and from the confluence of the Kandil Rud for 72 kms eastward, through the Qilla Saifullah sub-basin outlet and to the basin outlet north-east of Zhob. The mean annual precipitation is 242 mm. The structure of the valley is geologically complex. 1.3. Need for Identification of Potential Recharge Zones Recharge is defined as the addition of water to the aquifer and depends on the amount of precipitation and infiltration. The characteristics of unsaturated zone and movement of moisture fluxes control the amount of recharge in a region. Landcover/Landuse types also play an important role in ascertaining the recharge to the aquifer. All natural surfaces contribute in recharging groundwater to varying degrees. Lithology, geomorphology and soil characteristics play an important role in stimulating the recharge. The factors that



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govern the recharge in rocks are its intrinsic properties (fracturing, faulting and jointing, tectonic ruptures and solutioning cavities among karstic regions). However in alluvial regions, soil texture is the basic property controlling recharge. It is, therefore, imperative to effectively delineate PRZs and to identify cost-effective recharge measures. Landforms are the result of geological, tectonic, lithologic, geomorphic, pedological and sedimentological processes. The interactions of these processes produce a specific kind of landforms that have properties of recharge to the aquifer. Hence identification and characterising different kinds of landforms assist in establishing the PRZs. Government of Balochistan has undertaken construction of over 300 delay action dams for recharging the groundwater and 200 dams are in the pipeline. There is a continued decline in the vegetative cover in the catchments, which contributed in increased sediment load in floodwater causing exponential siltation of reservoirs and reduced infiltration. Thus, most of the stored water is evaporated. To remedy the situation M/S Nippon Giken Consultant under JICA evaluated the design of delay-action dams and recommended modifications comprising of pipe outlets to release the stored water slowly in the downstream river to have recharge in the river bed. No study has so far been conducted for the identification of PRZs in the province. 1.4. Objective of the Study The primary objective of the study was to develop methodology for the identification of PRZs using integrated GIS Model, geo-spatial databases and modeling for recharging groundwater in the three over-drawn river basins. The secondary objective was to use the methodology developed in the study to identify PRZs so that cost-effective recharge measures can be initiated in the province. 2. Methodology for the Identification of PRZs

2.1. Conceptual Model and GIS The GIS Data Model for the identification of PRZs is comprised of 4-5 spatial data layers that contribute to natural recharge. The focus is on geology and geomorphology, whereas soils, slopes and land use also contribute in recharge. Geomorphology and physiographic are the synonymous terms wherein the predominant factor is land cover that affects amount and nature of recharge. If conditions are favourable, more rainfall is intercepted and retained to allow it to percolate. The steep slopes as evident do not allow rainwater to infiltrate whereas moderate to lower slopes encourage infiltration. The snow cover in steep slopes contributes in percolation through crevices and fractures. Geology determines the infiltration with respect to rainwater. The lithologic characteristics play governing role in this realm. Physiography represents the nature and depositional environments of sediments, hence is another factor to consider in determining PRZs. The depositional characteristics of sediments govern the infiltration and percolation of rainwater to saturated zones through unsaturated media in the form of moisture fluxes. 2.2. Spatial Data Requirement The requisite spatial datasets for GIS framework for the identification of PRZs are described with the assumption that the baseline GIS layers (Towns/Villages, Roads Network and other Districts and basins and sub-basin boundaries) can be readily accessed for analysis. The GIS layers required for identification of PRZs are: a) Terrain Model (Topographic data); b) classified LANDSAT satellite imagery (remote sensing layer); c) geology (formations information); and d) streams network. The Terrain Model is basically translation into 3D surface generated by interpolation of elevation contours extracted from proposed 80 m DEM (Digital Elevation Model). The provision of Terrain Model in the scheme of analysis is an essential requirement for PRZs identification framework as it allows generation of slopes and also supports in determining the geomorphology of the area to incorporate realistic weights based ranking scheme as envisaged in the analysis model. Additional GIS datasets that can further strengthen the identification and analysis of PRZs in the GIS framework are: a) tectonic; b) locations of springs; and c) rainfall intensity layer. The baseline GIS layers used in the analysis platform are: a) basins and sub-basins boundaries; b) district boundaries; c) road network; and d) towns, villages and landmarks.

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2.3. Detailed Methodology for Identification of PRZs The detailed methodology for the identification of the PRZs at the basin level is of highly technical nature and beyond the understanding and interest of the general readers involved in water for Balochistan. Therefore, the detailed methodology is given in Annexure I at the end of the Policy Briefings, for the benefit of the readers who have understanding of hydrology, engineering and GIS based modelling. 3. Potential Recharge Zones in three Over-drawn Basins 3.1. Mapping of PRZs The GIS methodology for identification of PRZs heavily relies upon maps: a) five thematic maps as an input; and b) final output as maps. The mapping was done on a scale of 1: 250,000, where the area of three basins is spread on 12 such sheets (Figure-3). Major parts of basins are covered by six such sheets; six other sheets constitute smaller portions of basins. The mapping is based on boundaries of the basin. The GIS data layers are prepared keeping in view the limits of each basin. The final maps of PRZs of the basins were developed at three levels. The map of Pishin-Lora basin (Figure 4) is printed at a scale of 1: 1000,000 and the maps of both Nari and Zhob are printed at a scale of 1: 850,000 where these fit on A3 size of paper and portray overall situation in the basin. As the existing mapping system representing geology, hydrogeology and topography relies on scale of 1:250,000, the PR zoning has also been done on same scale. A set of 11 sheets of scale 1: 250,000 were prepared. Figure 3. Index of Maps for Three Basins 3.2. A Catalogue of Maps Three maps representing each basin were prepared and presented as under:

PRZs for the Pishin-Lora basin (Figure 4) PRZs for the Nari River basin (Figure 5) PRZs for the Zhob River basin (Figure 6)

Figure 4. PRZs for the Pishin-Lora basin



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Figure 5. PRZs for Nari River Basin

Figure 6. PRZs for Zhob River Basin



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The final mapping was made at a scale of 1: 250,000 corresponding to SoP sheets. Six sheets constitute the main area whereas the remaining constitutes small parts of the basins (Figure 3). These maps not only provide a compatibility with other thematic layers like geology, hydrogeology and topography but would also assist in regional development planning when used in conjunction with other maps and related information and data. The preparation of GIS of all these thematic layers will be a boon for the planner who intends to visualize interaction of all these layers and simulation of different scenarios of development interventions and regions. 3.3. Description of Mapped Potential Zones The three mapped potential zones; Low, Medium and High for recharge have been delineated on the basis of cumulative weightage of four thematic layers. Majority of the area of three basins lie in the medium potential zone, followed by low and high potential zones (Table1). Table 1. Statistics of potential recharge zones in three basins (km2)

Recharge Zones Nari River Pishin Lora Zhob River Total Weightage Low Potential Recharge 2365 2386 3786 8537 1 to 2 Medium Potential Recharge 16956 13242 12223 42421 2 to 3 High Potential Recharge 483 2128 392 3003 ≥4 Total 19804 17756 16401 53961

3.3.1. High Potential Recharge Zone This zone is normally found at the foothills, the area of crescent shaped alluvial fans and piedmont plains bordering the entire range of hills. This zone consists of moderately sloping land having rangeland characteristics and it provides grazing ground for livestock. In region, having slopes of < 50 and consisting of alluvial sediment of coarse texture (gravel and sand) with abundant natural vegetation or agriculture, the area is considered to be high potential zone. The concentration of tubewells in these areas is indicative of the possible good recharge to the aquifers. The lower reaches of these zones with relatively mild slopes and easy accessibility have contributed in the development of irrigated agriculture (tubewell, wells or Kareze). 3.3.2. Medium Potential Recharge Zone In the mountainous region, this zone consists of areas where fractured limestone and sandstone exists on gentle slopes. The precipitation falling on these rocks infiltrates rapidly to deep saturated zone owing to presence of fissures and cavities in it. In high altitude areas where slopes are very steep (110 to 200 or greater) the snow after melting infiltrates into subsurface contributing recharge to groundwater. This zone is also present in basin plains where coarse textured soils or alluvial sediment and conglomerate are found. In piedmont plain, where slopes are moderately steep (60 to 100 ), the area becomes medium potential. The piedmont and basin plains are generally used as a grazing land. The vegetation cover is substantially enhancing the soil water retention capacity. The area falling in medium recharge zone presents best possible areas for future recharge investments. 3.3.3. Low Potential Recharge Zone This zone in all the basins generally consists of mountainous regions comprising of hard rocks. Geology is predominantly Shale with varying degrees of mixed limestones and sandstones. Massive sandstones and limestones also exist as outcrop in this zone. The slopes are generally very steep (110 to 200 or > 200 ) allowing less time for precipitation to infiltrate into saturated zone. The soils are not much developed in this mountainous zone. However, the basin plains are composed of clayey to loamy soils of fine to medium textures. The soil texture and composition in basin plains inhibits the recharge/infiltration capacity of soil, thus creating a low potential recharge zone in the area. Similarly, the settlements in the basins are mostly located in the plains rendering it to be classified as low potential recharge zone. Landuse in basin plains is mostly composed of Khushkaba farming whereas in the hilly regions livestock grazing is dominant.



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4. Alternative Recharge Measures Recharge to groundwater is a natural process and occurs almost at all places with a varying degree. Enhancement of recharge has also been effected by means of human induced measures. Five main interventions identified are: a) watershed management; b) integrated Spate irrigation, Sailaba farming and storage dams; c) localized runoff harvesting and Khushkaba farming; d) delay action/storage dams; and e) integrated recharge well system.

4.1. Watershed Management Watershed management is aimed to upgrade existing natural resources through encouraging water harvesting in sloping lands for increasing vegetation and enhances recharge to groundwater. It also controls soil erosion hence reduces sediment loads in streams. Flow retarding structures (gabions, check dams, micro-catchments, etc.) are constructed to reduce flow velocities to enhance recharge and for plantations in piedmont and moderately sloping regions. The function of all these activities is to develop a mechanism that converge rainfall in specific areas having vegetation and to recharge groundwater. Advantages: The advantages are: a) up-gradation of natural processes results in recharge to groundwater on sustainable basis; b) integrated and participatory approaches result in direct stake of local communities; c) reduced sediment load in streams due to reduced soil erosion; and d) recharges shallow aquifers in short-term and ultimately deep aquifers in longer-term.

Disadvantages: The disadvantages are: a) relatively a long-term activity which requires integrated planning and participatory development; and b) regular supervision and maintenance of interventions are required by the community.

4.2. Integrated Spate Irrigation, Sailaba Farming and Storage Dams Spate irrigation and Sailaba farming is a millennium old system based on diverting floodwater, conveyance of water through channel network and spreading in the command areas. The earthen diversion bunds are generally made in a way that they break in case of high floods. It avoids substantial damage to the channel network, as very large floods are passed down the river rather than playing havoc with the Spate irrigation system. As a general rule when the land served by upper bund is fully irrigated, the farmers allow breaching of the bund so that the command area of the next bund receives the floodwater for irrigation till the water reaches to tail end users. During British period, two very important Spate irrigation schemes were developed: a) Nari headworks near Sibi; and b) Shebo Head works in Pishin. The Spate irrigation scheme comprise of diversion structure/weir and conveyance system which convey water to the command area. Water Users’ Institutions are strong around the Sailaba farming system since millenniums. However, with passage of time and involvement of public sector, this fabric has weakened. The bund system now-a-days is not maintained as vigorously as in the past due to deteriorating social cohesion among the water users. Advantages: The advantages are: a) around 8 to 23 billion m3 of floodwater is still available during mean to wet years, which can be stored in carry-over dams to release it during droughts; b) integrating storage dams with Spate irrigation and Sailaba farming would enhance recharge to groundwater and sustain Sailaba farming during droughts; c) Sailaba farming can provide new source of livelihood to the poor segments of rural Balochistan; and d) active involvement of water users is common as most of the systems are being managed by the water users and their organizations. Disadvantages: The disadvantages are: a) spatial and temporal variability in flows and higher sediment load demand systematic feasibility and design of Spate irrigation system; and b) higher capital investments needed for constructing integrated systems.

4.3. Localized Runoff Harvesting and Khushkaba Farming System It is the collection of runoff at localized levels from adjacent slopes or fields and its concentration in fields of Khushkaba farming. Similarly, micro-catchments can be constructed for harvesting of runoff for plantation



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of trees, shrubs or grasses, which supplements incident rainfall and ensures profitable harvests. Most of the fields are normally maintained in level form with bunds around the field to have uniform distribution of runoff and rainfall. Each field has an outlet from where excess runoff is drained into adjacent field. This minimises the chance of soil erosion and provide sufficient length of time for runoff to pond in the fields to improve infiltration. Advantages: The advantages are: a) runoff harvesting and Khushkaba farming are individual efforts and do not require hectic community mobilization process; b) ensure profitable harvest in arid environments where incident rainfall is not sufficient to grow crops or to achieve profitable harvests; and c) helps to harvest and store water in earthen ponds for domestic and stock water purposes

Disadvantages: The dis-advantages are: a) completely neglected by the public-sector institutions and no financial support is available due to higher risk, even the poorest-of-the-poor live in this ecology; and b) wheat is a major crop in winter and some coarse grain, pulses and fodders in summer depending on availability of rain and runoff. Normally, it is a single crop system due to temperate climate and farmers are thus switching to other systems. 4.4. Delay Action/Storage Dams Delay action and storage dams are constructed across ephemeral streams for either reducing the speed or storage of floodwater. A dam is constructed on the stream that has a sufficient catchment area to generate floodwater for storage. As the stream bed is generally composed of pervious material, it allows stored water to percolate to recharge groundwater. The overwhelming majority of community members during surveys supported the construction of delay action dams. Although, there is no clear evidence suggesting direct benefit accruing from construction of delay-action dams, yet the perception of communities can not be ignored. Certainly, the communities are getting some tangible benefits from delay-action dams as they favour its construction for replenishing groundwater. Community supports the construction of delay-action dam because it contribute in recharging shallow groundwater if constructed at right location and in right manner and it also bring job opportunities to the local people. Local notables also have opportunity to get contracts for such constructions. Thus, economic activity generated by the delay action dams is also one of the basic reasons of generating its demand in rural Balochistan. Now it is completely politicized. No doubt dams are needed but in most of the cases storage dams must be built instead of delay action dams having very short-life. Advantages: The advantages are: a) preferred intervention with the Public sector institutions, politicians and communities; b) it is a physical intervention and the economic activity generated by these schemes bring rapport to the Department; c) storage dams provide water for multiple purposes; and d) if the delay action dam is sited properly and operated effectively the downstream channel bed can support recharging groundwater Disadvantages: The dis-advantages are: a) sediments in reservoir area tend to clog river bed leading to reduction in infiltration capacity and leads to massive evaporation of stored water; b) delay-action dams are not cost-effective if siting of dam was made under political expediency rather than technical considerations; and c) pipe outlet some times get choked due to poor filter design. 4.5. Recharge Well System Recharge well system comprises of diversion structures integrated with conveyance network and detention ponds having permeable foundations. In case, foundation is on alluvial fan, measures to counter siltation and scouring are required. This type of arrangement is similar to Spate irrigation scheme except that it has injection wells installed within the tanks. The NDC Consultants (1995) recommended implementation of recharge well system in Hanna/Urak River comprising of: a) diversion structure on the main river for diversion of floodwater; b) feeder channel off taking from the diversion structure for conveying water to the channel network; c) provision of water to the recharge tanks from the feeder channel; d) injection wells installed within the recharge tanks; and e) special desiltation devices to be provided at the diversion structures, outlet heads on the feeder channel and at the top of injection wells.



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Advantages: The advantages are: a) large quantities of floodwater can be stored in series of large tanks which in turn can be used for extended period of time; b) during wet years, this system can provide supplies for irrigation purposes as well; c) technology except the injection well is already available in Shabo Headworks in Pishin district; and d) this system if integrated with Spate irrigation and Sailaba farming will provide a cost effective system of groundwater recharge.

Disadvantages: The dis-advantages are: a) injection system is not cost-effective per say both in terms of amount of recharge and life of the injection system. The real question is that can we recharge at a speed we discharge? b) conveyance system may require regular desilting having very mild slopes as sediment load is high in floodwater; c) regular desilting of recharge tanks and injection wells is essential for smooth functioning of the intervention; d) large investments are needed in construction of recharge well system; and e) hard to motivate communities to participate in recharge well systems if it is not integrated with Sailaba farming.

4.6. Site Selection and Common Problems 4.6.1. Site Selection Site selection for recharge interventions in different recharge zones is a fundamental question to be precisely addressed. The important points that should be considered while selecting suitable site for groundwater recharge are: a) develop a hydrogeological conceptual model (understanding); b) study and evaluate hydrometeorology of the selected location; c) identify location and estimate space in aquifer to store additional water; d) quantify the components of water balance; e) assess the quality of groundwater and source of water including the bacteriological impurities; and f) use of numerical models for assessment of selected locations. Evaluate the selected site for possibility of assessment of impacts of recharge measures in shallow and deep groundwater from that of the baseline information. There have been claims made for recharging groundwater using recharge wells but never documented using measured hydrological data because without separating the influence of recharge well from other sources of recharge, it is not possible to document the contribution of a recharge well. 4.6.2. Common Problems It is important to take into account the problems that can occur during implementation of the recharge measure. The most common problem is the entrance of sediment into reservoir and streambeds, hence reducing the efficacy of the intervention to debatable levels. Common problems encountered in site selection are: a) sediment load in floodwater and sedimentation process and sedimentation equilibrium in reservoir, channel network and water tanks; b) poor design of infiltration structure/borehole; c) stability of structure/borehole under operating conditions; d) O&M of recharge scheme; e) poor quality of groundwater (diffusive mixing); f) protection to groundwater quality; g) loss of infiltrated/injected water; h) transition from pilot to operational scale; i) policy, societal and religious acceptability; and j) availability and dissemination of information, knowledge and availability of skills.

5. Salient Findings of the Study

5.1. Identification of Potential Recharge Zones

There is a need to have GIS Integrated Model for analysis and mapping based on hydrological, geological, terrain, geo-morphological and physiographic considerations for identification of potential recharge zones.

Extreme variability was observed in the location of potential recharge zones in the three selected river basins – Pishin-Lora, Nari and Zhob

Groundwater recharge measures should not be viewed and contemplated in isolation from that of watershed management, Spate irrigation and Sailaba farming; rather efforts should be focused on to use these measures in an integrated and participatory manner.



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Linking of groundwater recharge measures is essential with livelihood generation schemes to have larger stake of rural communities in building and managing such schemes

Planning should be made at the sub-basin level, where appropriate measures can be taken collectively to improve conditions of catchment area, storage of water and management of Sailaba farming along with measures for recharging the groundwater.

5.2. Measures for Recharging Groundwater High Potential Recharge Zone

In this zone, all type of recharge measures can be introduced without any prejudice for recharging shallow to deep aquifers. Watershed management measures including flow retarding structures are beneficial for groundwater recharge. The presence of fissures and cavities in mountainous area enhances the rate of recharge.

In piedmont and downstream of the mountainous region, construction of storage/delay action dams and gabion leaky dams will be most beneficial as minimum amount of silt will enter into the reservoir area owing to watershed management activities.

In piedmont and flood plains (sand & gravel), Spate irrigation consisting of water storage facilities or recharge ponds and injection wells are considered potential measures to recharge groundwater. In certain areas, where proper site for storage pond in Spate irrigation is not available, spreading of floodwater in the fields is most viable option as a recharge measure.

Furthermore, in piedmont and plains, where suitable sites for delay action dam or Spate irrigation are not cost effective, small ditches or ponds in series along the river length will also help as a recharge measure.

Active participation of rural communities is a key in building effective recharge measures but these have to be linked with Sailaba farming and plantations in watershed to generate livelihood for rural communities and at the same time rural communities have active stake in the whole process.

Measures for Medium Potential Recharge Zone

In highlands and sub-highlands, watershed management in conjunction with gabion structures and storage dams at suitable sites will assist in recharging the groundwater, provided that watershed management activities are carried out in the upstream of dam through a participatory process and linked with Sailaba agriculture.

In plains, where slopes are normally mild, integrated Spate irrigation, water storage tanks and deep injection wells in the tanks can provide suitable solution as a recharge measure for shallow to medium aquifers. Water storage tanks and injection wells may be provided where subsurface geological formation allows deep percolation and underlying surface of alluvial sediment (clay & silt) is not very thick to prevent deep percolation.

Low Potential Recharge Zone

In low potential recharge zones, recharge measures for agricultural purposes are not cost-effective. However, interventions may be designed as a special case to support recharge for domestic and industrial uses in large urban towns.

6. Policy Issues and Reforms 6.1. Policy Issues

The piecemeal and isolated efforts in introducing groundwater recharge measures like delay action dams or watershed management do not provide cost-effective measure for recharging groundwater in Balochistan because there is extreme spatial variability in location of potential recharge zones in a province which constitute 43% geographical area of the country;

The groundwater depletion is largely due to the pressure to generate better livelihoods in environments which are conducive for high value horticulture. The subsidy on electric tariff and higher returns from deciduous fruits and high value vegetables are the major drivers;



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Lack of integrated and participatory scheme development process is a major reason for the failure of isolated schemes aimed for watershed management, Spate irrigation or groundwater recharge; and

In-adequate planning and design of schemes without considering the social, hydrological, geological, terrain, geo-morphological and physiographic considerations contribute in less effectivity of schemes related to watershed management and delay action or storage dams in recharging groundwater.

6.2. Policy Reforms

Formulate policy for the development of floodwater in Balochistan, which provides an immense opportunity and potential for generating new livelihoods and groundwater recharge measures in a province where un-employment is a major issue resulting in un-rest and insecurity among the un-employed youth;

Create awareness among the political leaders, experts and rural communities that integrate planning and implementation through a participatory and integrated scheme development process to cost-effectively recharge the shallow and deep groundwater in the province;

Link watershed management, water storage and Sailaba farming with the groundwater recharge objectives in the planning process so that investments are cost-effective on longer-term basis and communities own these schemes as they will be having larger stake due to improved livelihoods;

Effective linkages and coordination is needed between the line departments (Irrigation and Power, Agriculture and Forestry), NGOs and the private sector to plan and undertake coordinated projects in the areas of watershed-Spate irrigation-Sailaba farming-groundwater recharge schemes in the province; and

Highest priority must be assigned to the high potential recharge zones followed by medium potential zones. Activities in the low potential recharge zones must be considered in special cases i.e. recharging for domestic water use or other priority considerations because of higher cost of recharge measures. The high potential recharge zones are the most promising areas for cost-effective and sustainable recharge measures.



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The Policy Briefings is a Series of Issues, which will be prepared and circulated to the policy and decision makers in the province of Balochistan and in other provinces of the Country with an objective to synthesize and disseminate the studies outputs under the TA-4560 (PAK). The TA Project entitled “Supporting the Public Resource Management in Balochistan is being implemented by the ADB with the Department of Irrigation and Power, Government of Balochistan under the Balochistan Resource Management Programme. The funding is being provided by the Royal Government of Netherlands. The Policy Briefings are also based on the research work done by other national and international institutions with an objective to get benefit of the work done elsewhere. The comments and suggestions can be sent at the following address: Project Coordinator, TA 4560 (PAK), Arid Zone Research Center, P.O.Box.63, Brewery Road, Quetta, Pakistan. Email: [email protected] Phone No. 0321-9561517/0300-9561517 Fax: 081-2853616 Websites: http://www.brmp.gob.pk/pbriefings.html http://www.brmp.gob.pk/tpbriefings.html Reference: Riaz, M., B. Sani, K. Babar and S. Ahmad. 2008. Potential Recharge Zones ofOver-drawn River Basins of Balochistan, Pakistan. Vol. (4), No. (8), TA-4560 (PAK), Quetta, Pakistan.

The topic to be addressed in the next Issue of Policy Briefings is “Social and Farmers’ Institutional Impacts on Water Rights, Allocation Rules and Water Availability on Lower Riparian in Spate Irrigation of Balochistan”. The topic includes; a) Social and Institutional Context of Spate Irrigation; b) Farmers’ Institutions; c) Share Crop Arrangement; d) Operation and Maintenance of Spate Irrigation; e) Social Fabrics of Spate Irrigated Areas; f) Water Rights, Allocation and Distribution to Lower Riparian; g) Incorporating Social and Institutional Fabrics in Spate Characterization and Classification; h) Policy Issues or Reforms; and i) Guidelines for Future Investment Projects.



Annexure I. Methodology Developed for the Identification of Potential Recharge Zones in River Basins of Balochistan, Pakistan 1.1. Spatial Data Requirement 1.1.1. Classified Slope Layer (generated from DEM of sub-basin) DEM with a resolution of 80 m for the province serves the purpose of generation of slopes for the three basins functionally usable at a scale of 1: 250,000. The developed GIS Framework includes a user friendly menu driven scheme to generate slopes classified into 5 categories ranging from 1 to 20 degree classes and higher. The Terrain Model was selected as baseline analysis layer and user through interactive dialogue based procedures generated the required slopes categories. The values in the generated output slope grid are classified in colour toned groups that represents spatial distribution of slopes in a given basin in selected slopes group. The GIS based slope model provides an efficient system to effectively distinguish high, medium and low relief areas and thus provide technical basis to determine flow patterns and gradients in the basins. This unique vertical integration of parameters projected along baseline topology such as piedmonts and valleys provide a strong analysis environment on GIS platform that is readily deployable (Figure 1.1).

Figure 1.1. Grid system for estimation of slope

1.1.2. Classified Raster Geology Layer The geology layer is prepared from the vectorization of a geological map of the province. The scale of the map is 1: 250,000 and distinguishes various stratigraphic units and lithological characteristics. The Attribute Table of the layer contains the weightage assigned to each group of lithologies. For raster matrix analysis, the geology vector layer at each sub-basin is converted into raster grid classified on the basis of lithological formations data such as shale, limestone, gravel, etc. These raster classified data is again reclassified using the weight assignment scheme (Table 1.1). Table 1.1. Scheme of weights assigned to different criteria and classes

Criteria Classes Weight Alluvium 2 Cong/Sandstone/Clay 2 Conglomerate 3 Gravel 4 Limestone 3 Sandstone 3 Shale 1 Shale/Limestone 2

Geology

Shale/Sandstone 1 Piedmont Plains 4 Flood Plains (Active and Abandoned) 5 Basin Plains 1 Other alluvial soil 4

Geomorphology

Gravelly soil 5 0 – 1° 4 2 – 5° 5 5 – 10° 3 10 – 20° 2

Slope

> 20° 1



1.1.3. Classified Raster LANDSAT Multi Spectral Imagery Potential utilization and integration of satellite imagery for Land use analysis at each sub-basin is an integral dataset of the Geodatabase. The merging and reduction of classes was carried out with reference to DEM for assessment of high and low terrains and also with reference underlying LANDSAT multi spectral imagery. The land use assessment using LANDSAT imagery was conducted with respect to slopes; geology and soil cover vector layers and distinguishable vegetative, hydrological and other formations of LANDSAT image. 1.1.4. Catchments Weighted Classified Drainage Assessment Scheme Natural drainage pattern of watershed is an important input in the PRZs Identification Model Development Scheme. The methodology entails development of an automated procedure based on generation of vector delineated segments of streams network from the DEM at sub-basin. The generated vector streams network Attribute Table with each segment ID Number and its predecessor and successor connectivity segment, an automated procedure was developed to generate vector streams network from DEM and to generate a classified scheme of streams on the basis of streams segments lengths. The methodology enables identification of longest stream(s) network that determines predominant confluence pattern of sub-basin and hence contributes in recharging aquifer. Drainage pattern is a major consideration in the identification of PRZs (Figures 1.2 and 1.3).

Figure 1.2. Flowchart to generate DEM based drainage stream network ArcHydro based algorithm also generates length of each segment that can be used classifying length based streams drainage thematic map. It is observed that the DEM resolution is an important consideration in generating streams whereby plain areas show gaps in delineated vector streams due to the capture resolution and minimal undulation in z-dimension. In order to justify gaps and unavailability of data in the analysis model, the methodology used was to overlay major streams in each sub-basin with the DEM based streams layer resulting in filling the missing drain segments in the plains. The sub-basin drainage pattern evaluation scheme is important for reference as it is not only important from the surface model hydrology perspective but also readily verifies the PRZs that are generated using slope-geology-geomorphology raster analysis model. 1.1..5. Classified PRZs Layer The GIS Model for identification of PRZs is based on raster matrix operations with weighted overlay. The generated output raster layer is a classified raster grid with zones of low, medium and high recharges identified in color codes schemes.

Arc Hydro DEM Vector

(Streams)

Topo Sheet Main Stream Vector

Merge

Streams Connectivity

Attribute Table

ClassificationBased on

Length



1.2. Spatial Functional Approach The implementation scheme to identify PRZs in each sub-basin is designed and developed using ArcMap, ArcCatalog and ArcTools Modules of ArcView 9.2 ESRI software suites and applications (Figure 1.3). The functional model scheme entails spatial raster functions adopted to delineate suitable locations on the basis of weighted pixels using: a) Raster Matrix Operation (reclassification operation); and b) raster – raster overlay (weighted overlay).

The Study ArcCatalog based Geo-database provides layers for each sub-basin for assessment of PRZs are: a) geology (raster); b) slopes (raster); and c) classified LANDSAT image (raster). The PRZs Identification Model is developed using ArcGIS 9x Model Builder to automate the spatial processes and work flow in the form of a representative set of routines. The proposed PRZs Model represents the requisite input layers that are processed using spatial function routines such as raster slopes generation and raster matrix operation in the form of weighted overlay. The model work flow schematic is generated from the model builder and the processes are colour coded in terms of inputs and output data results.

1.2.1. Raster Weighted Overlay Formulation Weighted Overlay is a technique for applying a common measurement scale of values to diverse and dissimilar inputs to generate an integrated raster surface representing results on the basis of weights assignment scheme. In the PRZs Model, raster based weighted pixel operation technique is adopted to identify suitability of the PRZs on the basis of ranking criteria (Table 1.2).

Figure 1.3. Flowchart of PRZs Identification Spatial Model Table 1.2. Weight assignment scheme of GIS Model

The raster weighted overlay spatial matrix operation only accepts integer raster values as input. In order to use weighted overlay technique, the continuous raster values must be reclassified as integer values before applying the weights overlay operation. The input raster of preferred slope zones pixels (0 to 5 degrees) are weighted in the form of higher integer values (reclassified) and steep slopes weighted with lower integer values. Similarly, the preferred pixels of geological formations such as gravel and alluvium are weighted with higher values for higher infiltration capacity compared to lower integer assigned values of shale and clay pixels. The three raster inputs (slopes, geology & classified LANDSAT image) are evaluated using raster weighted overlay with 34, 33 and 33% influence factors to produce a raster layer classified into pixels of high integer values to pixels of lower values, providing immediate suitable locations of PRZs (Figure 1.4). The raster – raster overlays geospatial functionality entails assignment of weights at each pixel level using ArcGIS raster reclassification tool. The weights assignment scheme was applied to each respective GIS Model classified geo-spatial layers. The slope, geology and geomorphology (Landuse) layers are classified into 5 categories, respectively. The GIS model classified layers are generated initially as non-integer

Old Value New Value 0-1° 4 1-5° 5 5-10° 3 10-20° 2 >20° 1



classified groups which are reclassified using ArcGIS tool into respective integer values ranging from 1 to 5 as per weight assignment scheme (Table 1.2 and Figure 1.5). Input 1 = Slope Input 2 = Geology Input 3 = LANDSAT Output = PRZ

Figure 1.4. Example showing Raster Pixels Weighted Overlay The GIS Model addresses each of the given classes as GIS based spatial generated data with associated ranking given in Attribute Tables of GIS generated data layers. The model as shown in Figure 1.6 is generated to produce the raster output layer with the resulting pixel geometry. The preferred pixels with higher integer weights are the PRZs based on geomorphologic localized setting of the basin. The final layer is generated through addition of three primary layers (geology, slopes and landuse/classified). Three categories of landforms have been derived depending upon the potential recharge capacities. The three zones need different kinds of activities to enhance their natural contribution to the overall recharge however, the structural interventions for increasing recharge will be limited to the medium and high potential zones. The PRZs are summarised in Table 1.3. It can be deduced that the areas with weightage of 4 to 5 should be considered real PRZs for alternative recharge measures. But still it is arguable that remaining parts of the basin should not be left without any kind of intervention (Figure 1.6).

Figure 1.5. Reclassified assignment of values for geology layer

Table 1.3. Categories of PRZs

The minimum requirement is rehabilitation of rangelands and catchments where extensive recharge activities are practised. The proposed GIS framework is based on ESRI ArcView 9.2 series suites of software with a modular integration of ArcMap/ArcCatalogue and ArcTools raster-vector modules of analysis. The envisaged scheme develops spatial data layers required for assessment of PRZs, the overlaying procedures are elaborated and final maps are generated at sub-basin level to provide planners a reasonable and reliable tool for site selection. Large scale mapping will be useful for local level assessments using satellite image and performing simple editing and improvement of data. An important point to note is that each of the GIS layers either vector or raster are available in “Study Geo-database” and provide required coverage in the form of generated polygon vector layers of PRZs with information in Attribute Tables in terms of area of each PRZ in the basin.

Figure 1.6. Potential recharge categories based on cumulative weights

Potential Recharge Weightage Low Potential Recharge < 2 Medium Potential Recharge 2 - 3 High Potential Recharge 4 - 5

5 5 3 5 1 1 1 5 5

3 3 5

1 3 1

5 3 1

4 4 5

4 3 1

5 3 3

=+ +

4 4 3 2 1

4 4 3

4



Low

High

Well Point

LEGEND

1.3. Additional Model Validation Data The PRZs identified in the analysis model can also be verified by generating thematic water level fluctuation map given the availability of water table contours. The static water table points collected in the Pishin sub-basin area with dugwell point locations were incorporated to generate water table fluctuation thematic contour surface. It is observed that high water table areas which signifies sub-surface recharge potential areas conforms to the identified PRZs generated in analysis model (Figure 1.7). An important point to note is that each of the given GIS layers either vector or raster will be available in “Study Geo-database” and shall provide required coverage in the form of generated polygon vector layers of the identified PRZs with information in Attribute Tables in terms of area of identified PRZs. The generation of spatial data required for identification of PRZs is described in detail to highlight different kinds of data and approach to prepare data layer for functional model (Figure 1.8).

The constituent components of each layer depending on their potential recharging have been assigned the relative weights. Figures 1.9 to 1.11 give pictorial representation of different thematic layers and respective weights.

Figure 1.7. Water table fluctuation thematic map



Figure 1.8. ESRI Arc GIS 9.2 Functional Model Schematic Diagramme for identification of PRZs

Figure 1.9. Geological units and weights Figure 1.10. Physiographic/geomorphological classification Pishin sub-basin raster

1.4. Outputs from Interaction of Spatial Data Layers The final output of the interaction of three layers of data provides a thematic map giving rise to three categories already described in Table 1.3. It was decided to develop and produce the final PRZs of the three basins at sub-basin level to enhance the utility of the output. Hence 27 such kinds of maps were produced. However, a comprehensive map of such zones was also developed for each basin providing an effective tool for planning.



Figure 1.11. Raster classified slopes of Pishin sub-basin with weight assignment scheme

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