Application of HEC-HMS for Flood Forecasting in Kabkian Basin and Delibajak Subbasin in Iran

Abstract

Rainfall-runoff processes in small subbasin Delibajak(16.3 km 2) and Kabkian basin(846.5 km 2) in kohgilouye and boyerahmad , iran were examined. in fact, Delibajak is one of the subbasins of Kabkian basin. In this study, basins divided into a number of sub-basins where the hydrologic parameters may vary from one sub-basin to another. In such case, lumped models may be labeled as "semi-distributed."The hydrologic model HEC-HMS (Hydrologic Engineering Center, Hydrologic Modeling System), used in combination with the Geospatial Hydrologic Modeling Extension, HEC-GeoHMS. The SCS curve number method (Soil conservation Service, 1972) was considered for the Rainfall-runoff modelling and The model was carefully calibrated and verified in subbasin and basin using simultaneous historical observed data. The determination coefficients and coefficients of agreement for all the flood events were above 0.9, and the percent errors in peak flow and volume were all within the acceptable range. As well, the hydrologic parameters, curve number and initial abstraction were compared in this two basin. In the Kabkian basin, curve number and initial abstraction, ranges from 61 to 66, and 33 mm to 40 mm, respectively. In the Delibajak subbasin, this parameteres ranges from 51 to 53, and 47 mm to 51 mm. This variationes is due to differences in slope, geologic formations,vegetation cover and land use in subbasins.