Google Earth Imageries for Validating Groundwater Recharge Zone in Basaltic region

Abstract

A majority of the existing groundwater potential studies in the literature lack adequate validation. In developing countries, it is attributed to many reasons including- poor/limited data on water yield, sparse spatial and temporal data on wells, lack of data protocol/sharing, a weak ground water governance structure such as disparate agencies, lack of registration/georeferencing of irrigation wells. A rapid, simple and replicable approach is proposed to overcome these difficulties using Google Earth imageries for visual interpretation, interwined with cadastral data and telecommunication for a representative block located in basaltic region of Maharashtra, India. Each of 1684 irrigation well in the study area was enumerated, its irrigation area estimated and verified through available records, field visits, telecommunication with well owners and georeferenced to link with land parcel identification number and build well information system. Functional and defunct wells were distinguished using deacadel timeline data. Nine major biophysical and environmental factors namely geomorphology, soil, land use land cover, slope, lineament density, drainage density, topographical wetness index, curvature and aspect were analyzed to asses the groundwater recharge potential (GWP). The GWP zones were verified using the georeferenced enumeration data on wells, their density and area irrigated per unit well. The number of wells, functional well density followed an order high < moderate < moderate to poor < poor to nil, i.e. highest density (0.034/ha) in high potential zone and lowest density (0/ha) in poor to nil potential zone. Number of defunct wells also exhibited linear correspondence with least share (51%) in ‘high’ potential zone and higher share (76%) in ‘moderate to poor’ potential zone. It is concluded that Google Earth imageries provide direct and conclusive well enumeration, its irrigated area and therby accurate means of evaluating GWP zonation. It has immense potential for use in many countries where historical data are inadequate to assist groundwater management/governance.