GIS-MCDA-based groundwater recharge potential zonation and artificial recharge site identification in coastal Ramanathapuram, India

In this study, an effort was made to demarcate the zones of groundwater recharge potential along with the identification of preliminary candidate locations for the construction of artificial recharge structures (ARS) in the coastal region of Ramanathapuram District, Tamil Nadu State of India through an integrated approach of GIS & MCDA technique. There are eight thematic layers like rainfall, lineament density, drainage density, geomorphology, lithology, soil, slope, and land use/land cover (LULC) used in this study depending upon the influence of each factor on the recharge of groundwater. The random forest technique was adopted to prepare LULC map. The recharge potential zones generated from the analysis were categorized into very high, high, moderate, low, and very low recharge potential zones. The very high potential zone occupies 38.94% (1621.38 km 2 ) of the district, followed by high (22.23%; 925.64 km 2 ), moderate (19.12%; 796.29 km 2 ), low (11.00%; 458.14 km 2 ) and very low (8.71%; 362.55 km 2 ). From the above spatial distribution, it can be seen that rainfall, lineament density, drainage density, geomorphology and favorable lithology and soil conditions have a strong influence on the recharge potential, where the relatively favorable zones occur in central, northern, coastal and deltaic areas of the district. Preliminary candidate locations for construction of artificial recharge structures like check dams, percolation tanks, nala bunds have been determined based on groundwater potential zones, hydrogeomorphological features and drainage conditions. The aforementioned sites are screening level locations that need to be validated through field hydrogeology before their application. The findings of this study are useful for spatial planning for conservation of groundwater and artificial recharge operations in the semi-arid coastal region of Ramanathapuram District.