Derivation a Geomorphological Unit Hydrograph Based on Cascade Linear Reservoirs (Case study: Liqvan Catchment)

The Instantaneous Unit Hydrograph (IUH) concept is widely applied for runoff estimation in watersheds with scanty data. In this paper, the method of geomorphological unit hydrograph of reservoir (GUHR) was applied to Liqvan watershed located in East Azarbaijan, Iran. This method is based on the cascade of linear reservoirs which are assumed to contain the stream flow of related sub-watershed area. Hence sub-basins are replaced with consecutive reservoirs according to watershed geomorphology. Indeed the model is the routing of flood through these reservoirs and to determine the unit hydrograph in the basin outlet. The results showed GUHR has efficiency enough in simulating the rainfall-runoff by the use of watershed geomorphologic characteristics of a basin. The sensitivity analysis of model was carried out by changing the parameter values. Results showed that to decrease in K values caused to increase in the peak of hydrograph (qp) with less time of peak (tp) and vice versa.