Assessment the Variation of Runoff Parameters in Al-Dwereeg Valley Basin, Iraq

Abstract

Rainfall-runoff phenomena are controlled by several complicated parameters. Each analysis model is use specific parameters as inputs for the analysis and the accuracy of the any model depend on the input parameters and processing algorithm. The relationship of rainfall-runoff is one of the most complex hydrologic phenomena; due to the great spatial and temporal variability of basin characteristics and precipitation patterns. Study area located in the eastern parts of Iraq and extended on 3731square kilometers; the basin is boundedbetween latitudes 32^o 00’ to 33^o 20’ N and longitudes 47^o 10’ to 48^o 00’ E. The area is suffering from the absence of gauge stations for the water discharge at the outlets of the main sub-basins, that's make the validation of estimated values of surface runoff more difficult task. The main objective of the study is to analysis the relation of rainfall– runoff using Soil Conservation Service (SCS)- Curve Number (CN) losses method. The analysis was carried by WMS v.11 software and HEC-1 model. The results of HEC-1 simulation, shows the characters of surface runoff i.e. runoff volume, peak flow, time of peak flow, Time of concentration for four sub-basins with respect to antecedent moisture conditions (AMC). The results show the effect of soil types, land use/land cover, vegetation densities, morphometric parameters and variation of rainfall intensity on the spatial variability of the surface runoff parameters in the study area.