Mapping of Salt Affected and Waterlogged Areas using Geospatial Technique

Abstract

Integration of remote sensing and geographical information system (GIS) technique for the delineation of salt affected and waterlogged areas has become an innovation in the field of ground water research. The main objective of the present investigation is to identify and map the surface extent of salt affected and waterlogged areas during pre-monsoon and post-monsoon season using multi-temporal satellite images and its relationship with soil, rainfall, seasonal groundwater fluctuation and canal command areas. For this purpose, Satellite images from IRS P6, LlSS-III sensor, on a scale of 1:50,000 have been used for delineation of thematic layers such as salt affected and waterlogged areas. The area covered under post monsoon waterlogging (seasonal) comprised of as 114.79 sq km area which is 3.60% of the study area whereas post monsoon waterlogging (permanent) comprised of 89.37 sq km area, which is 2.80% of the study area. The map depicting salt affected soils in the area indicates calcareous fine loamy, coarse-loamy, fine loamy and very fine soil comprising 2799.43 sq km, 9.26 sq km 363.73 sq km and 2.80 sq km area respectively. The monthly TRMM 3B43 rainfall data for the period of 1998-2009 covering the month of June to September shows rainfall varies from less than 965 mm to 1165 mm in the entire state. Depth to groundwater level recorded at select locations by Central Ground Water Board (CGWB), Government of India, for the period 2004-2005 during pre and post monsoon period indicated that a large portion of the area is under groundwater induced waterlogging conditions where groundwater occurs at a depth of 0-3 m below ground surface. The soil and rainfall map clearly specifies that salinity are pre dominant in areas with shallow groundwater levels and high rainfall. Canal command areas comprised the highest waterlogging and salt affected areas in their vicinity as a result of seepage and over irrigation.