Determination of the Effective Factors in Flooding Potential of Darrehshahr Drainage Basin Based on Hydrological Homogeneous Area

Reliable estimations of flooding potential are extremely important for flood management in arid and semiarid regions without or lack of data. One of the most important methods in flooding potential estimation is curve number method (CN) of American Soil Conservation Service (SCS). In this research flooding potential and identifying of effective factors on flooding events at sub-catchments and hydrological homogeneous areas of Darrehshahr drainage basin has been studied and compared. In view of this، the study area classified to three homogenous cluster using cluster analysis. The curve number method was used to estimate runoff and maximum discharge of the sub-catchments and homogeneous clusters. The layers and data including land use، hydrological groups of soil، maximum 24 hours precipitation، the CN measures، infiltration (S)، runoff volume (Q) and maximum discharge (Q max) at each sub-catchment and hydrological homogeneous clusters were calculated. Finally، factor analyses based on 20 parameters were used to identify the effective factors on maximum discharge at sub-catchments and homogeneous clusters. The results showed two physiographic parameters (area and drainage density) in and six physiographic parameters (area، main stream length، sum of streams، basin drainage density، bifurcation ratio and time of concentration) at sub-catchments and hydrological homogeneous regions selected as effective parameters in flooding potential، respectively. In addition، at the hydrological homogeneous regions the parameters including forest area، pasture area and percent area of high infiltration formation were selected as highly loading factors. Therefore، we can conclude that the hydrological homogeneous clusters have higher accuracy than the sub-catchments in the estimation of flooding potential using CN method.