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UDK 552.5

Z. Sagintayev a, M. Sultan a, S.D. Khan b, S.A. Khan c, K. Mahmood c, E. Yan d,A. Milewski a, K. Chouinard a

IDENTIFICATION OF AQUIFER TYPES AND POTENTIAL WELL LOCATIONS USING GIS AND REMOTE SENSING TECHNOLOGIES IN THE PISHIN LORA BASIN

(a) Department of Geosciences, Western Michigan University, Kalamazoo, MI, USA (b) Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX

(c) National Center of Excellence in Mineralogy, University of Balochistan, Quetta, Pakistan (d) Environmental Science Division, Argonne National Laboratory, Chicago, IL, USA

Corresponding email: jaysagin@gmail.com; zhanay.sagintayev@wmich.edu

GIS and Remote Sensing are powerful technologies for conducting research in remote and inaccessible regions in the world. Water is one of the basic necessities for the development of societies and agricultural communities. With the continuous rise in populations of the developing countries world-wide, many of these countries are now facing serious water shortages that require dedicated efforts to assess and develop their groundwater resources. One of these locations is the Pishin Lora basin in Pakistan, an area that has been receiving waves of immigrants fleeing the war-infested neighboring Afghanistan. The watershed encompasses the Balochistan (Pakistan) and Kandahar Province (Afghanistan), two of the poorest and most dangerous areas in the World, where Taliban tribes live. Climate in the provinces is semi-arid, and extensive deserts cover most of the two regions. Increasing population, excessive use of groundwater, and arid climates (precipitation: ~ 100 mm/yr) have all contributed to progressive decline in groundwater levels (1989-present: 3m decline/yr). A cost-effective, interdisciplinary approach was adopted that integrates remote sensing data with observations extracted from other data sources (e.g., geochemistry, field geology, drilling, geophysics, and modeling) to: (1) assess the groundwater resources in these areas and to develop sustainable extraction scenarios, and (2) identify aquifer types, and select criteria for locating potential productive well locations. A manuscript titled “Remote Sensing Contributions to Hydrologic Modeling in Arid and Inaccessible Watersheds, Pishin Lora Basin, Pakistan" summarizing our results pertaining to Task 1 was recently published in the Journal of Hydrological Processes. In this manuscript, we outline our research and methodology pertaining to the implementation of task 2. Specifically, the identification of isolated groundwater aquifers in fold and thrust belts using the Pishin Lora basin as our test site. The methodology was applied to the northeast part of Pishin Lora (NEPL) watershed, which is located on the border of Pakistan and Afghanistan. Currently, the main water source for the local population in NEPL is from alluvial aquifers collecting runoff from surrounding mountains. Our findings indicate that additional potential isolated groundwater aquifers in bedrock should be targeted. These include: (1) nose of plunging folds (synclines), (2) fractured bedrock along faults and shear zones, (3) intersection of fractured bedrock (fault/fault; fault/shear zone; shear zone/shear zone), (4) intersection of shear zones with plunging folds. In general, areas where a number of folds, faults, fractures, or shear zones intersect are areas of high ground water potentiality. The intersection of these discontinuities will enhance porosity and will create conditions favorable for ground water storage in fractured basement rocks.

1. INTRODUCTION. Kandahar, province of Afghanistan, and Balochistan, province of

Pakistan, are two of the largest provinces in these two countries, yet these provinces have the smallest number of people per unit area. This is largely due to the paucity of water resources related to the prevailing arid to semi-arid conditions in these areas. The climate in these provinces is typical of deserts elsewhere, low rainfall (~100 mm/y) and extreme variations in temperature are observed. The Pishin Lora Basin (PLB) is located on the border of these two provinces (Fig. 1). In recent years the indiscriminate and unplanned use of groundwater resources to meet water requirements in Balochistan has led to unsustainable overexploitation of groundwater resulting in a progressively increasing deterioration in groundwater quality and quantity in Balochistan /1/. Over the last decade, water shortage problems have increased primarily because of the droughts that affected the area and because of the steady wave of immigrants from neighboring Afghanistan fleeing the war zone. All of these factors have contributed to a dramatic rise in the local population of the Quetta

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valley, part of the Pishin Lora (PL) watershed (16,671 km2) encompassing areas in Pakistan and Afghanistan (Fig.1).

Figure 1: Pishin Lora Basin Location and extent of the entire Pishin Lora watershed are shown in red, the northeastern part of the Pishin Lora (NEPL) basin is shown in green color, streams in blue color, border between Afghanistan and Pakistan are shown in purple color.

Quetta, capital of Balochistan province, is bearing the brunt of this migration /2/. According to the Government of Balochistan, drought-flooding cataclysms have affected 85 % of people in Balochistan: 7,917,000 livestock died (76%), more than two million people migrated during 1998–2000 (drought years), three big dams crashed and seventy people died in the flood of 2005 /3/, and 420 during the floods of 2007 /4/. Water-related problems are not only restricted to water shortages, long drought periods are usually followed by rare flooding events that pose threats to human life and property. All of these factors are pointing to the urgent need for the assessment and development of surface and groundwater resources. Such studies are needed for the development of sustainable water management scenarios in Balochistan. Over the past two years, we published our findings /5–7/ that were largely concentrated on the construction and calibration of a hydrological model for the NEPL basin. Our findings were summarized in our recent publication titled “Remote Sensing Contributions to Hydrologic Modeling in Arid and Inaccessible Watersheds, Pishin Lora Basin, Pakistan" that was published in the Journal of Hydrological Processes. In this manuscript, we discussed the general deficiency in the understanding of the hydrogeologic setting of the Pishin Lora watershed, and addressed the temporal and spatial partitioning of precipitation in the study area. We also investigated the groundwater potential in the area and developed sustainable extraction scenarios. Among the solutions we proposed, was the construction of delay action dams in carefully selected locations to enhance recharge (Fig.2).

In this manuscript, we develop procedures for the identification of potential isolated groundwater aquifer types in NEPL and select criteria to enable the identification of potential locations for productive wells from remotely acquired data sets using GIS technologies. Currently, the main water source for the local population in NEPL is from alluvial aquifers collecting runoff from surrounding mountains. Over-pumping in this region has caused the water table to drop over

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the years. There is a need to identify alternative settings (isolated groundwater aquifer types) if we are to meet the increasing needs for groundwater in the study area.

Figure 2. Subbasins of NEPL with reservoirs (dams) locations.

Distribution of major (NE, NW, and Southern basins) and minor (104) subbasins within the NEPL watershed. Also shown are the locations of Burj Aziz Khan Discharge Station and the Khushdil Khan and Kara Lora reservoirs (dams), in subbasins 21 and 44, respectively, and the location of the proposed additional reservoirs (dams): reservoir 1 (subbasin 40),

reservoir 2 (subbasin 41), and reservoir 3 (subbasin 68) /7/.

2. METHDOLOGY.We integrated inferences from remote sensing data with observations extracted from other relevant data sources (e.g., geochemistry, field geology, geophysics) for a better understanding of the hydrological setting, the groundwater potentialities, and for identifying potential locations for productive wells. Water quality and water history investigations were also cited as important parts of the promised tasks. We worked on the following tasks to reach our targets:

I. Stage one is the preliminary stage. During this period, our efforts were concentrated on the collection of field data, compilation of published data, digitization of compiled data, development of a GIS to host the accumulated data sets, and on the construction of a web-based GIS for data analysis and distribution.

II. Stage two includes analysis of the accumulated data sets in a GIS environment for the purpose of: (1) identifying isolated groundwater aquifer types in the study area and, (2) selecting criteria for identifying well locations for potential productive wells.

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An extensive web-based GIS (http://www.esrs.wmich.edu/webmap/) was developed that incorporates all relevant datasets including co-registered digital geologic maps, remote sensing data, hydrologic parameters, drainage patterns, structural elements, well locations, soil maps, etc. The comprehensive datasets are in categories such as: Geophysics, Topography, Remote Sensing, Hydrology, and Geology. Using the information in the web-based GIS, including the locations of successful productive wells in relation to structural and lithologic observations displayed, led to interpretations pertaining to the distribution of major isolated groundwater aquifers types in the study area. The extracted relationships are used to identify the locations of potential isolated groundwater aquifers with similar field relationships.

3. POTENTIAL ISOLATED GROUNDWATER AQUIFER TYPES. One of the advantages for the generation of digital datasets and their incorporation into a web-based GIS is to enable the analysis of spatial datasets for a better understanding of the hydrologic settings in the study area. Regional and detailed geological maps, remote sensing data, and topographic maps were used in a GIS environment to identify lithologic and structural controls on existing wells locations. We then used the acquired understanding of such settings to look for locations that portray similar geologic and hydrogeologic settings. The idea is that the location of productive wells gives us clues as to where we should be looking for groundwater elsewhere.

As described earlier, currently the main water source for the local population in NEPL is from the alluvial aquifers collecting runoff from surrounding mountains. Our findings indicate that there are additional potential isolated groundwater aquifer types in the bedrock that include: (1) fractured bedrock along faults and shear zones, (2) intersection of fractured bedrock (fault/fault; fault/shear zone; shear zone/shear zone), (3) intersection of shear zones with plunging folds.

Aster and LandSat Thematic Mapper (TM) band ratio images were used for the identification of rock and soil types. Figure 3 is a color composite generated from three TM band ratio images, TM band ratio 5/4 (blue), 5/1 (green), and 5/7 (red) images. TM band ratio 5/4 is sensitive to the rock content of Fe-bearing aluminosilicates, the 5/1 is sensitive to the rock content of spectrally opaque minerals, whereas the 5/7 is sensitive to hydroxyl (OH)-bearing minerals /8–10/. In Figure 3, serpentinite appear in shades of red, rocks rich in Fe-bearing aluminosilicates in shades of blue, and granitic rocks in shades of green. The same products could be used to identify folds and to map thrust and strike slip faults. Shear zones and folds are easily delineated from band ratio maps. Areas, where a number of folds, faults, fractures, or shear zones intersect are areas of high ground water potentiality. The intersection of these discontinuities will enhance porosity and will create conditions favorable for ground water accumulation in fractured basement rocks.

Figure 3 shows an example of one of the bedrock aquifer type (intersection of shear zones) in the area. Successful wells (green circles) are located at the intersection of NE-SW and NNE-SSW trending shear zones (white arrows). The area outlined by the oval at the intersection of these two shear zones is the area suggested for detailed geophysical work and for drilling productive wells (Fig. 4).

4. IMPLICATIONS. The developed methodologies can be applied to many parts of the less-studied watersheds of the world, especially in areas where field data is inadequate and accessibility is limited. One of the main features of our methodology is the utilization of global datasets that are readily available for most of the world’s land surface. The adopted methodologies are not a substitute for traditional approaches that require extensive field datasets, but they could provide first-order estimates for rainfall, runoff, and recharge over large areas that lack adequate coverage with stream flow and precipitation data.

Acknowledgements. Funding was provided by the U.S. Agency for International Development, in cooperation with the Higher Education Commission of Pakistan.

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Figure 3. Potential isolated bedrock groundwater aquifers at intersection of shear zones on NEPL. Potential bedrock isolated groundwater aquifers at the intersection of shear zones (area outlined by the oval).

Green circles represent successful well locations and the image is a Landsat TM band ratio image: 5/4 (blue), 5/1 (green) 5/7 (red).

Figure 4. Potential isolated bedrock groundwater aquifers at the nose of plunging fold. Processed ASTER images showing productive and proposed wells. Left image: shows examples of productive wells (green circles) located on the

nose of a plunging syncline in folded Chiltan limestone outcrops. Right image shows potential locations (red circles) for productive wells in a similar setting (nose of folded Chiltan limestone). Red lines were added to highlight the plunging nature of the fold.

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