Hydrogeology of hard rock aquifer in kashmir valley: Complexities and uncertainties

Abstract

Groundwater occurs in varied geological formations. Its occurrence in geological system is controlled mainly by the lithology (porosity and permeability) and structure (fractures, faults, dykes). The unconsolidated sediments referred to as continuous media, although vulnerable to contamination under shallow conditions, always form important source of water due to appreciable porosity and permeability. However, the water supply from these aquifers is dwindling worldwide due to overexploitation, global warming, easy exploitation, poor management etc. As the demand of freshwater exceeds rapidly than its renewal, the groundwater levels have gone down rendering a good number of wells dry. Hard rocks can also be good aquifers only if the secondary porosity is developed in the form of fractures or solution cavities and/or weathering. Fortunately all consolidated subsurface rocks are fractured to some degree with a scale ranging from microcracks to crustal rifts (Bonnet et al., 2001). The fractures generally increase the hydraulic conductivity of the rocks if the discontinuities are more permeable than the parent rock. Sometimes fractures may form barriers to flow if the contained material is less permeable than the host rock. Geological formations with fractures, solution cavities and large openings are referred to as discontinuous media. The occurrence, exploration and exploitation of groundwater in these media continue to intrigue and challenge hydrogeologists (Narasimhan, 2005) due to very high heterogeneity and anisotropy. © 2008 Springer Netherlands.