Calculated Geomorphologic Instantaneous Unit Hydrograph (GIUH) and Width-Function based Instantaneous Unit Hydrograph (WFIUH) in the ungauged watershed

The role of unit hydrograph is very important in prediction of floods in the rivers, design protection and control structures in the catchment area. Therefore in the basin without hydrometric stations, by using mathematical and empirical relationship and based on climatic data, the water level in the basin is estimated. Two methods of Geomorphologic Instantaneous Unit Hydrograph and Width Function Instantaneous Unit Hydrograph, Due to use of the watershed physical characteristics and GIS software, estimate the instantaneous unit hydrograph in ungauged basin with reasonable accuracy. WFIUH method for allocating different flow rate in hillslope and the main canal basin, is more coordinated with reality. In this article instantaneous unit hydrograph of Ghorveh basin with an area equal to 14/67 km in Kurdistan, with the help of GIS and ArcHydro extension and PEM4PIT extracted. The results of this two methods were compared and showed that concentration time estimate approximately the same by each method, almost 4.6 hours. But WFIUH method by utilizing the flow rate proportional to slope, covering more detail in it.