Determination of Synthetic Unitgraph for Selected Small Watersheds in Upper Damodar Valley

Abstract

A unitgraph is a typical hydrograph repre- senting the direct runoff due to one inch of rainfall. excess generated uniformly over the watershed atershed area at a uniform rate during a given period of time. A synthetic unitgraph is a unitgraph which can be developed with the help of parameters representing the rainfall and water-shed characteristics, without actually measuring the flood flow. Unitgraph is one of the important tools for flood prediction work from watersheds. A unitgraph of a certain duration can be used to construct 'S' curve. This 'S' curve can then be used to construct unitgraph of any desired duration. Determination of flood peak and total flood volume, required for the construction of small dams, reservoirs, culverts etc. can be done with the help of unitgraph. In India most of the watersheds are ungauged.