Abstract
Surface water monitoring is a necessary component of researching ecological and hydrological processes. Recent improvements in satellite-based remote sensors have ushered in a new era in the area of surface water monitoring. The assessment and mapping of water resources in the semi-arid regions are one of the challenging tasks for the research domain of hydrogeologists and decision-makers. In this study, an inventory of existing ancillary data and remotely sensed data, i.e., Landsat 7 ETM+, Landsat 8 OLI/TIRS, and DEM data used for monitoring and mapping the surface water resources in the semi-arid regions of south India. For monitoring and mapping the water resources, twenty years of land cover changes were assessed using the Modification of Normalized Difference Water Index (MNDWI) techniques. Each MNDWI land cover has been classified into five categories viz., fallow land, vegetation land, developed land, moisture soils, and surface water bodies, based on the pixel values varying from +1 to -1. The results of the research reveal that the surface water bodies vary from year to year over the past two decades. The fallow land (36.20 %), vegetation lands (35.37 %) are decreased, and developed land (22.56 %), moisture soils (4.81 %), and surface water bodies (1.06 %) are increased over the past two decades from 2000 to 2020. Most land cover categories differed statistically from one another, however, when defining vegetation with varying water content, there were some commonalities. MNDWI is found to be efficient in identifying water bodies.