Study and Mapping of Ground Water Prospect using Remote ... - IGU

V.K.Srivastava, Devendra Nath Giri and Pawan BhardwajRESULTS AND DISCUSSIONOn the basis of integrated and weighted analysisof various thematic maps such as geological, geomorphological, digital elevation model, verticalelectrical resistivity sounding data, ground water tabledepth map and geo morphological map in Arc GIS,we have generated two very important maps viz.; A)Hydro-geomorphological map (Figure 7) showinggroundwater potentiality in terms of geomorphologyand B) Ground Water Prospect Map (Figure 8) ofDhanbad district.A) Hydro-geomorphological MapThis map shows five distinct hydro geo morphologicalfeatures from the point of view of water resourceprospect as well as for application of watermanagement practices, in order to enhance the statusof water resources in the region.Unit 1) - Denudational Hills: The area is coveredwith mixed forest and has moderate to low sloperesulting in moderate run off. It is shallow and welldrained. It is gravelly loamy soil and non-sticking.It is friable when moist. The region is covered with fewlineaments/fractures with subradial drainage pattern andhence the groundwater prospect is moderate to good.Unit 2) - Pediment: The area is covered withbushes with cultivated land in low valley and hasmoderate to steep slopes (5-10%). The region hasdense lineaments. Drainage pattern is dendriticto sub parallel with linear parallel radial drainagepattern. The groundwater prospect is good to verygood.Unit 3) - Undulating Upland: These featuresrepresent the buried pediments with intermontanevalley. These areas are characterized by moderateto high steep slope resulting in very high run off.Groundwater prospect is poor.Unit 4) - Pediment Inselberg Complex:These are isolated rock hills, knobs, ridges, orsmall mountains that rise abruptly from a gentlysloping or virtually level surrounding plain. The unitrepresents barren land with shallow well drainedgravelly sandy soil on sloping landscape with severeerosion. Drainage density is poor with sub parallel tosub radial pattern and groundwater prospect is poor.Unit 5) – Pedeplain / Peneplain: Pedeplains arerelatively flat rock surfaces formed by the joining ofseveral pediments and Peneplains. They are gentlyundulating, almost featureless and plain. The regionis covered with moderate number of lineamentswith sub parallel to sub dendritic drainage pattern.Groundwater prospect is low to moderate.B) Ground Water Prospect MapThe final integrated map as generated by applyingthe weighted overlay analysis in Arc GIS showsfive prospect grades in terms of water resourcespotentiality viz.; very good, good, moderate, poorand very poor (Figure 8). Good Water prospectzone Geomorphologically covering alluvial fills andvalley fills covers nearly 45% area (yellowish greencolor tone) . Very good zones cover only 12% of thestudy area (green color tone). They are locatedalong lineaments and in pediment areas. Moderateprospect zone covers 15% of the area (yellowish colortone). Features like buried pediplains, peniplainsand denundational hills come under this category.Whereas poor regions cover up to 22% (orangecolor tone). These features are mainly confinedto undulating upland and buried pediments withintermontane valley. Lastly, very poor groundwaterprospect zones are approximately 10% (red colortone). These features include dissected pediments,inselberg complex and residual hills.CONCLUSIONSThe present integrated study has brought out thefollowing conclusions.Geologically it is observed that the groundwater ismainly confined to secondary porosity i.e. fracturedzone, fault, joint and weathered column. It isobserved from field survey and also from variouswells located in the region the hard granite gneissesand meta basic dykes sometimes act as barriers forthe groundwater flow in the region.Based on resistivity variation with depth, it ispossible to estimate the depth and distribution ofgroundwater. The low resistivity value of less than51ohm-m indicates the presence of weathered zone,which is favorable for groundwater accumulation.The subsequent underlying layers (hard and massiverocks) are more resistive than the first layer.From the generated ground water resourceprospect map, it is observed that high potential zonesare mainly located along lineaments and in pedimentareas. Alluvial fills, valley fills are good potentialzones. The geomorphic units like buried pediplains,peniplains and denundational hills are moderate togood groundwater prospective zones. Undulatingupland and buried pediments with intermontanevalley, mainly confined in undulating upland, arethe regions of poor groundwater prospecting zones.Very poor potential regions cover a small part of totalstudy area (confined to dissected pediments, inselbergcomplex and residual hills).62