Peak Flood Discharge (PFD) estimation at a desired site on a river is critical for the planning, design, and management of hydraulic structures including dams, bridges, and barrages, as well as the design of storm water drainage systems. These include different types of floods such as standard project flood, probable maximum flood and design basis flood. In case of large river basins, the hydrological and stream flow series of a significant duration are generally available. However, for ungauged catchments, more data is not available other than rainfall which may also be of shorter duration. Therefore, in such cases, statistical analysis by fitting probability distribution to the rainfall data needs to be carried out for the estimation peak flows. Synthetic unit hydrographs (SUH) based on catchment characteristics can be used as a tool to produce flood hydrographs from rainfall records, especially in such catchments. In the present study, SUH based approach has been used to develop flood hydrograph for ungauged catchment. The method employs the unit hydrograph suggested by Central Water Commission (CWC), India. Watershed delineation and estimation of various catchment parameters for the computation of peak flow was computed using geographical information system (GIS). The flood peak value for 50-yr and 100-yr return period was found as 1057 m3/s and 1152.36 m3/s respectively. The results of study concludes that SUH method able to estimate hydrological parameters including peak flow discharge and can be utilized for the computation of design flood in ungauged catchments.

Synthetic Unit Hydrograph (SUH); Design flood; Flood hydrograph; Ungauged catchment; Geographic Information System (GIS).