Providing a method for determining the flood producing regions based on the relationship between flooding index and morphometric

River basin planning is an essential factor for sustainable development and land management. Therefore, sub-basins prioritizing and detecting morphometrically characteristics to identify the hydrological behaviors of watersheds and designing management strategies are very important. The aim of present study is to prioritize the flooding of the basin by distributional method and provide a method for determining the flood generating areas in the Tangrah watershed. To this end, the inputs of the rainfall-runoff model were extracted and then the model was calibrated and validated. For this purpose, the inputs of the rainfall-runoff model were extracted and then modclark model calibrated and validated. In the next step, in order to determine the flooding of homogeneous units and sub-basins with unit flood response method, sequential removal and replacement of these units and simulation of flood hydrographs for designed rainfall were carried out at the Golestan National Park's rain gauge station. Then the effect of each homogeneous unit and sub-basin on the total output hydrograph in the watershed was calculated. Finally, for a flood with a return period of 50 years and 100 years for non-statistical watersheds, a correlated multivariable correlation between morphometric parameters and flood index was presented. The results of the potential runoff production map with the return period of 50 and 100 years showed that the runoff production potential was upward downstream of the basin, and the homogeneous unit 116 was recognized as the most effective unit in the high runoff potential, which is due to more rainfall as well as The steep slope and high (CN) in this homogeneous unit, the runoff production potential is nearer the outlet of the basin than the upstream areas. The results of this study showed that by integrating the GIS and hydrologic models, we can investigate the interaction of physiographic and climatic factors on the spill potential of watersheds. Considering the peak synchronization and the flood roughing role in the rivers, prioritized sub-areas as desired.