Comparative assessment of image enhancement techniques for mapping of groundwater‐rich alluvial fill zones of western Cuddapah District, Andhra Pradesh, India

Abstract

Alluvial/valley fills potentially form excellent groundwater zones and therefore their distribution over a terrain is very important in hydrogeological terms. Given the advantage of synoptical view and multispectral characteristics, digitally recorded remotely sensed images and their processing techniques provide a unique opportunity to map such lithounits with great accuracy and swiftness. The study area suffers from acute groundwater deficiency and therefore mapping the alluvial fill zones can help considerably in groundwater exploration and targeting. In this study an attempt was made to develop a comprehensive digital enhancement package to digitally enhance and extract the alluvial/valley‐fill regions from an Indian Remote Sensing Satellite (IRS) 1D Linear Image Self Scanning (LISS) III image. Of the several image enhancement techniques tried, the Hybrid Colour Composite (HCC) and Square root of Multiplied Bands (SMB) methods were found to be particularly effective and best suited for such an exercise. The final alluvial fill map prepared was ground checked through several field surveys, which also included checking the potential groundwater well yield of the mapped zones. The study demonstrates the usefulness of digital image processing (DIP) in mapping alluvial fill zones and the efficacy of remote sensing in groundwater exploration.

Acknowledgements

We thank the University Grant Commission, New Delhi, for a fellowship grant to A.P.M., and NDC, NRSA, Hyderabad for their cooperation in procurement of the satellite data.