Watershed is a geographically dynamic unit area that contributes runoff to a common point. The effect of land use/land cover (LU/LC) changes on runoff from watersheds has long been recognised. Remote sensing (RS) and GIS techniques can be used effectively in watershed runoff models. Manimuktha sub–watershed, the study area, for which base map, soil map and LU/LC map were prepared by using RS data and SOI topography sheets. The daily rainfall data of Virudhachalam was collected and used to predict the daily runoff from the watershed using GIS–based SCS–CN method (USDA, 1972). For the mini–watersheds the LU/LC details were derived in a GIS environment and their effect on runoff potential was studied and the mini–watersheds were categorised as 'moderate', 'high' and 'very high'. From the results it was inferred that the mini–watersheds with crop land and fallow/harvested land were categorised as 'very high' and mini–watersheds with more percentage of dense forests were categorised as 'moderate' runoff potential.
Keywords: watershed, land use, land cover, SCS-CN method, runoff potential, remote sensing, geographical information systems, GIS, India, rural watersheds, crop land, fallow land, harvested land, dense forests