Utility of magnetic data in delineation of groundwater potential zones in hard rock terrain

摘要

Exploration and management of ground-water in hard rock terrain is a challengingtask, as the potential groundwater zonesare associated with fractured and fissuredzones. Identification of such features insubsurface is a difficult task. The ground-water potential in such an environmentdepends upon the thickness of the weath-ered/fractured layer overlying the base-ment rocks. An integrated geoscientificstudy has been carried out to understandthe aquifer set up, especially the ground-water flow system in weathered fracturedgranitic zone in Maheshwaram watershed,having an areal extent of -55 km~2 situ-ated at about 30 km south of Hyderabad,India. The area under study lies betweenlongitudes 78 deg 24 min 30 sec and 78 deg 29 min 00 secE aswell as latitudes 17 deg 06 min 20 sce and 17 deg 11 min 00 sceN(Figure 1). The weathered zone extendsto a depth of 20 m followed by fracturingat many places1 and shows variable den-sity of fractures. The nature and degreeof weathering are observable from anumber of defunct dugwells that are gen-erally truncated by erosion and overlainby a few decimetres of red soil; theweathered mantle has quite homogene-ous thickness of less than 3 m throughoutthe watershed~1.