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Groundwater prospects analysis through hydrogeophysical parameters and hydrogeomorphic zonation - a case study in parts of Kewta Watershed, upper Barakar basin, Bihar
Ashok Kumar, Savita Tomar* and L.B. Prasad Remote Sensing Application Centre, IGSC-Planetarium, Patna - 800001, India * Noida, UP, India
Abstract The study area is parts of 'Kewta watershed' of Koderma (lower Hazaribagh) plateau. It is located in between the latitude 240 09' - 240 13' and longitude 850 20' - 850 28'. In the present study, hydrogeomorphic zonation has been carried out through remote sensing technique. Hydrogeophysical characteristics of aquifer have been analysed with the help of vertical electrical sounding. Study deals integrated approach for groundwater exploration. The results of hydrogeomorphic and hydrogeophysical approach have been correlated and outcomes have been highlighted in the paper. Analysis has indicated that each hydrogeomorphic zone can be further divided on the basis of hydrogeophysical parameters. Numerous depressions (sub-surface basin) on basement surface have been identified with the help of Digital Basement Terrain Modeling (DBTM). These depressions play important role in understanding the aquifer storage and retrieval. But these features have not been resolved as separate identity in hydrogeomorphic zonation. The hydrogeomorphic zonation coupled with hydrogeophysical parameters has given better understanding of groundwater storage and retrieval. Integrated approach has also increased the authenticity of ground water prospects determination. Analysis of deep buried pediplain shows that the top layer (10 m) consists of silt and clay (may be depositional) and principal aquifer material i.e. weathered horizon is lying below the depositional material. This has important bearing in planning utilisation and development of groundwater. Introduction The Kewta watershed (Upper Barakar basin) is a part of Koderma plateau of Bihar. It is located between the latitude 240 09' - 240 13' and longitude 850 20' - 850 28'. It is a typical undulating granite gneiss pediplain and regional slope is towards west with maximum pediplain height 450 meters in east and minimum 430 meters in the west from m.s.l.. The areal extent of study area is 29 sq. km. Groundwater occurs under water table condition and aquifer is un-confined / semi confined in nature. The yield of dugwell depends on the thickness of weathered and fractured horizon (Karanth, 1987). Study area has limited groundwater reserves due to unconfined nature of aquifer system. At present available reserve is under utlised. Analysis of 3-D aspects of the aquifer is essential to understand the aquifer storage and reterival system unconfined aquifer. It has been observed that dugwell depth normally does not go beyond 11 m b.g.l.. The pre-monsoon variation of water table is 7 to 10 m in deeply weathered zone. Seasonal fluctuation in water table is about 1 m. In moderately weathered zone, water table varies between 4.5 - 7.5 m on uplands and there is less seasonal fluctuation in water table. In shallow weathered zone, water table in the month of January is below 6.5 m on uplands and less regional variation. But seasonal fluctuation is between 3 - 4 m. In present paper, authors have tried to demarcate different hydrogeomorphic zones with help of remotely sensed data. Systematic vertical electrical sounding (VES) has been also carried out and digital basement topographic model (Kumar, 1997) has been generated. The ground water prospect has been determined through both the approach and results are further correlated to improve the groundwater prospects zonation.  Fig 1: Hydrogeomorphic map of parts of Kewta watershed  Fig 2: Depth of Basement zonation map parts of Kewta watershed  Fig 3: Resistivity Zonation at depth of 11m b.g.l. of parts of Kewta watershed
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