Basement topography and aquifer geometry around Ken Graben, India
0 An attempt has been made to study the subsurface geological and geomorphological details of the Banda area and to demonstrate their relationship to aquifer geometry in the region. In this study a systematic analysis of a basin was made by integrating satellite data with the available spatial ground dataset using ILWIS (Integrated Land and Water Information System). The approach involved regional interpretation of geomorphological and structural features exposed at the surface and relating these to the subsurface relief. The area chosen for the study is situated within the marginal Gangetic alluvial plain in Banda district of Uttar Pradesh, India. The region has a varying thickness of alluvium composed of alternating sand/kankar (carbonate concretions) and clay strata deposited on an uneven basement. Different image processing techniques such as image smoothing, contrast stretching, false colour composite, and principal component analysis were used to enhance the lithological and geomorphic features and their effect on associated features like vegetation and soil. Subsurface features of importance in ground water exploration such as buried channels were identified. Several geomorphological features such as sand bars, point bars, meander scrolls, abandoned channels and ravines were identified and the region was classified in terms of five geomorphic units. A methodology to generate a digital elevation model of subsurface topography with the help of depth to bedrock contours is proposed. On the basis of this model, the configuration of the basement topography in the region was previously reported by the authors In this paper sites for favourable aquifer disposition and various subsurface geomorphic features which are potential sites for ground water development are identified using Geographic Information System (GIS) capabilities. An overlay of the enhanced image on a map showing the thickness of granular zones on the digital terrain model of the basement has led to an understanding of the exact subsurface geometry of the aquifers and their relationship to surficial geomorphic features. Ground water hydrogeological status has been inferred from integration of the information from structural, lithological, geological, topographic and hydrological data.