The watershed is a natural hydrological entity that covers a specific aerial expanse of land surface from which the rainfall runoff flows to a defined drain, channel, stream or river at any particular point. It is a general phenomenon governed by the topography of the terrain. Based on the size, the hydrological unit is termed as water resource region, basin, catchment, sub-catchment, watershed, sub-watershed and micro-watershed respectively. The smallest hydrologic unit in the hierarchal system is termed a micro-watershed, having a size of 500-1000 ha.
The Microwatershed Atlas of India aims at identifying and recognizing each micro watershed in the country with a distinct spatial extent and Unique National Code. The state-wise publication of the atlas has been contemplated considering the enormous volume of spatial data available with the Soil and Land Use Survey of India. The Microwatershed Atlas of India has been designed in such a way that the reader shall be able to locate and identify the micro-watershed of his interest falling in different districts of different states of India.