DEMARCATION OF GROUNDWATER PROSPECT ZONES THROUGH RS AND GIS TECHNIQUES IN A BASIN

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1 IGC 2009, Guntur, INDIA DEMARCATION OF GROUNDWATER PROSPECT ZONES THROUGH RS AND GIS TECHNIQUES IN A BASIN G.N. Pradeep Kumar Professor, Deptt. of Civil Engineering, S.V.U. College of Engineering, Sri Venkateswara University, Tirupati , India. saignp@gmail.com. P. Srinivas Associate Professor, Deptt. of Civil Engineering, R.V.R. & J.C. College of Engineering, Chowdavaram, Guntur , India. vasu77_p@yahoo.come.f ABSTRACT: A systematic planning of groundwater development using modern techniques is essential for the proper utilization and management of this precious but shrinking natural resource. Groundwater resources potential has been evaluated in Kurmapalli Vagu basin in A.P. using RS and GIS techniques. Various thematic maps like base map, drainage map, geology map, geomorphology map, slope map, drainage density map and land use/land cover map of the study area have been prepared using Arc GIS software. These thematic maps have been integrated and appropriate weightage have been assigned to various factors controlling occurrence of groundwater. The results show that there are five categories of groundwater prospect zones ranging from very good to poor. The results are in general agreement with the acquired yield data of the existing dug wells and bore wells. This depicts the favourable prospect zones in the study area for evaluation of groundwater resources. 1. INTRODUCTION Water is the elixir of life, plays an important role in the wealth of nation particularly in a country like India, which is predominantly an agriculture dependent economy. While the surface water is inadequate to meet the demand for various purposes, groundwater is the only alternate resource which will serve the purpose. In the absence of any planned groundwater withdrawal approach, many times random drilling of bore wells results into failure. Further, this indiscriminate exploitation has led to decrease in groundwater potential, lowering of water level and deterioration in groundwater quality. It is therefore necessary to develop sustainable groundwater management scheme to properly utilize this vital resources, which in turn requires delineation of groundwater potential zones. Remote Sensing technology has already been accepted as an effective complementary tool in natural resource mapping the world over. Satellite imageries are increasingly used in groundwater exploration because of their utility in identifying and outlining various ground features that may serve as direct or indirect indicators of the presence of groundwater. Remote Sensing, with its advantage of spatial, spectral and temporal availability of data covering large and inaccessible area within short time, has become a very rapid and cost effective tool in assessing, monitoring and conserving groundwater resources. GIS consists of a powerful set of tools for collection, storing, retrieving, transforming and displaying spatial data from the real world for a particular purpose. In the recent years, GIS is being used for various purposes such as feasibility study of recharge sites, finding contaminated sites etc. Many researchers such as Murthy (2000) Naga Rajani et al. (2006) have used remote sensing and GIS techniques for groundwater exploration and identification of artificial recharge sites. Ravi & Mishra (1993), Jaiswal et al. (2003), Jothiprakash et al. (2003), Prasad et al. (2008), Chowdhury et al. (2009), have utilised RS and GIS techniques to delineate groundwater potential zones. GIS has also been considered for multicriteria analysis in resource evaluation. Boutt et al. (2001) and Elkadi et al. (1994); have carried out groundwater modelling through the application of GIS. In the present study IRS P6 LISS III & IRS 1D PAN merged remote sensing data acquired on 27 th April 2008, geocoded at the scale of 1:50,000 and Survey of India (SOI) toposheet numbers 56 L/9, 56 L/13 have been used for preparation of various thematic maps such as base, drainage, geology, lineament, geomorphology, slope, drainage-density and land use/land cover. An attempt is made to integrate these data through the application of GIS to demarcate the groundwater potential zones in the study area. 2. STUDY AREA Kurmapalli Vagu basin is located at about 55 km south east of Hyderabad on Hyderabad-Sagar road. It lies between E longitude and N latitude and forms part of 56 L/9 and 56 L/13 SOI topo sheets. The location map is shown in Figure 1. The areal extent of Kurmapalli Vagu basin is sq. km of which sq. km of Chintapalli mandal in Nalgonda district, sq. km of Yacharam mandal in Ranga Reddy district and 2.68 sq. km of Madgul mandal of Mahbubnagar district of Andhra 818

2 Pradesh. It is mainly drained by Kurmapalli Vagu which originates 1.0 km northwest of Kishanpalli village. The basin is characterized by poor soil cover, scarce vegetation, erratic rainfall and lack of soil moisture for major part of the year. Recurring droughts coupled with increase in groundwater exploitation results in decline in groundwater levels. The surface runoff goes to stream as instant flow. Most of the drainages flow southeastward forming upper catchment. In order to manage and develop sustainable scheme, it is vital to delineate the groundwater potential zones. The base map of the study area is shown in Figure 2. Fig. 3: Geology Map of Kurmapalli Vagu Basin Fig. 1: Location Map of Kurmapalli Vagu Basin 4. DRAINAGE Drainage pattern of any terrain reflects the characteristics of surface as well as subsurface formations. The drainage pattern, in general is dendritic. Drainage density (expressed in terms of km/sq.km) indicates closeness of spacing of channels. More the drainage density, higher would be runoff. It varies from 0.02 km/sq km to more than 6 km/sq km. The drainage map and drainage density map are shown in Figures 4 and 5. Fig. 4: Drainage Map of Kurmapalli Vagu Basin Fig. 2: Base Map of Kurmapalli Vagu Basin 3. GEOLOGY The basin is underlained by Archaean rocks. Massive porphyritic granitic rocks occupy high hill ranges and isolated hills. The northwestern edge and northern part are occupied by such hills of hard crystalline massive granites and is shown in Geology map in Figure 3. The South-eastern fringe area is occupied by kankar covered with clay. The remaining part is occupied by weathered granite and gneisses. Fig. 5: Drainage Density Map of Kurmapalli Vagu Basin 819

3 5. SLOPE Slope of any terrain is one of the factors controlling the infiltration of groundwater into subsurface, hence it is also an indicator for the suitability for groundwater prospect. In the gentle slope area the surface runoff is slow allowing more time for rainwater to percolate and hence more infiltration. Slope map of the area as shown in Figure 6, indicates that it varies from 0 to more than 35%. cover. Information on existing land use/land cover and pattern of their spatial distribution forms the basis for any developmental planning. Current land use has to be assessed for its suitability for groundwater prospects. Land use/land cover map is shown as Figure 8. Fig. 8: Land Use /Land Cover Map of Kurmapalli Vagu Basin Fig. 6: Slope Map of Kurmapalli Vagu Basin 6. GEOMORPHOLOGY Geomorphology reflects various landforms and structural features. These units are deciphered from the remote sensing data and are shown in Figure 7. The major geo morphological units found in the study area are Denudational Hills, Residual Hills, Rocky Pediment, Moderately Weathered Pedi plain, Shallow Weathered Pedi plain, Valley Fill and Shallow Weathered Pedi plain with Alkaline Soil. 8. INTEGRATION THROUGH GIS The integration of various thematic maps describing favourable groundwater zones, into a single groundwater potential map has been carried out through the application of GIS. Arc GIS software has been utilised for analysis purpose. It required three steps namely Spatial Database Building, Spatial Data Analysis and Data Integration. 8.1 Spatial Database Building The tools provided in Arc GIS Catalogue of Arc GIS software have been used to create the scheme for feature data sets, tables, geometric networks and other items inside the database. The Secant method has been followed for geodatabase building. 8.2 Spatial Data Analysis It is an analytical technique associated with the study of locations of geographic phenomena together with their spatial dimension and their associated attributes. The various thematic maps as described above have been converted into raster form considering 100 m as cell size to achieve considerable accuracy. These were then reclassified and assigned suitable weightages. Fig. 7: Geomorphology Map of Kurmapalli Vagu Basin 7. LAND USE /LAND COVER Land is one of the important natural resources and is a precious asset. The actions related to land and water management influences the vegetation and land use/land 8.3 Data Integration Each thematic map provides certain clue for the occurrence of groundwater. In order to get all these information unified, it is essential to integrate these data with appropriate factor. Various thematic maps are reclassified on the basis of weightage assigned and brought into the Raster Calculator function of Spatial Analyst tool of Arc GIS for integration. 820

4 9. GROUNDWATER PROSPECT ZONES MAP The groundwater prospect zones map which is shown in Figure 9 has been categorized into five zones i.e., poor to very good from groundwater potential point of view. In order to make the classification more realistic, data on the yield of existing wells have been collected. About 438 wells were monitored and the yields of these wells have been found to vary from 135 to 1450 m 3 /d. The yield distribution with the location of wells is shown in Figure 10. Yield from the wells located in the zones demarcated as good and very good is found to vary from 700 to 1000 m 3 /d, where as the yield from the wells located in poor zone is determined to be 150 to 300 m 3 /d. Fig. 9: Groundwater Prospect Zones Map Fig. 10: Yield Distribution Map of Kurmapalli Vagu Basin 10. CONCLUSIONS Kurmapalli Vagu basin has been classified into five different groundwater prospect zones namely very good, good, moderate to good, moderate and poor covering different percentages of the study area. Since the major portion (more than 75%) of the study area exhibits very good to moderate to good groundwater prospect, it can be inferred that the groundwater resource is adequately available in the study area. The categorization of groundwater potential zones are in general agreement with the acquired yield data of the 438 existing dug wells and bore wells. This depicts the favourable prospective zones in the study area for evaluation of groundwater potential. Further, the results of this study demonstrated that the integrated RS and GIS based approach is a powerful tool for assessing groundwater potential based on which suitable locations for groundwater withdrawals could be identified. REFERENCES Boutt, D.F., Hyndman, D.W., Pijanowski, B.C. and Long, D.T., (2001). Identifying Potential Land Use-derived Solute Sources to Stream Base Flow using Groundwater Models and GIS, Groundwater, 39(1): Chowdhury, A., Jha, M.K., Mal, B.C. and Chowdary, V.M., (2009). Delineation of Groundwater Prospect Zones Using Remote Sensing and G.I.S. Techniques: A Case Study, Proceedings of the International Conference W E E S , New Delhi, Conducted by NIH, (1): Elkadi, A.I., Oloufa, A.A., Eltahan, A.A. and Malik, H.U., (1994). Use of a Geographic Information System in Site Specific Groundwater Modeling, Groundwater, 32(4), Jaiswal, R.K., Mukherjee, S., Krishnamurthy, J. and Saxena, R., (2003). Role of Remote Sensing and GIS Techniques for Generation of Groundwater Prospect Zones Towards Rural Development An Approach, International Journal of Remote Sensing, 24(5): Jothiprakash, V., Marimuthu, G., Muralidharan, R. and Senthil Kumar, N. (2003). Delineation of Potential Zones for the Artificial Recharge Using GIS, Journal of the Indian Society of Remote Sensing, 31(1): Murthy, K.S.R., (2000). Groundwater Potential in a Semiarid Region of Andhra Pradesh: A Geographical Information System Approach, International Journal of Remote Sensing, 21(10): Naga Rajani, K.V, Swamy, M.V. and Venkateswara Rao, B. (2006). Estimation of Groundwater Resources: A Case Study of Kurmapalli Watershed in Nalgonda and Ranga Reddy Districts of Andhra Pradesh, Proceedings of ICHWAM-2006 conducted by C.W.R, J.N.T.U, Hyderabad, (1): Prasad, R.K., Mondal, N.C., Pallavi Banerjee, Nanda Kumar M.V. and Singh, V.S. (2008). Deciphering Potential Groundwater Zone in Hard Rock through the Application of GIS, Environmental Geology Journal, 55: Ravi, P.S. and Mishra, D. (1993). Identification of Groundwater Prospective Zones Using Remote Sensing and Geoelectrical Methods in and Around Saidanagar area, Dokor block, Jalaun District, U.P., Journal of Indian Society of Remote Sensing, 21(4):

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