Flood Hydrograph Simulation Using Simplified Advection-Diffusion Equations in Kashkan Watershed, Lorestan Province

Investigation of floods as one of the most common natural destructive phenomena is very important. Due to the problem of deficiency and defect of hydraulic data in most hydrometric stations in the country, flood hydrograph simulation by hydrological and hydraulic models is helpful. There are several hydrological and hydraulic models to simulate flood hydrographs. The present study has investigated the performance of Advection-Diffusion relationships of 36 flood phenomena in 5 study reaches of Kashkan river and its tributary. Physical properties related to the studied periods and hydrometery data related to each flood phenomenon, including discharge and scale of the input and output station, were used to determine the Manning roughness coefficient and flood simulation. Evaluation of obtained hydrographs indicates the acceptable accuracy of the model in term of simulating values of flood trends and discharge. In order to evaluate the accuracy of the model results, different coefficients such as: Nash-Sutcliffe, RMSE, Volumetric Efficiency, Kling-Gupta and R correlation coefficient were calculated. A value above 0.5 for the Nash-Sutcliffe coefficient in 29 flood phenomena out of 36 studied phenomena, and an acceptable range of other coefficients for all studied flood phenomena, indicates the verifiable results of flood hydrograph simulation using simplified propagation methods at reach scale for studied watershed. Therefore, Advection-Diffusion relationships can be used in similar watersheds to the study area to simulate floods.