Given Iran's location in arid and semi-arid climates and considering recent flood-related damages, studies in flood management have gained significant importance. Through hydraulic and mathematical modeling, the hydraulic behavior of rivers can be simulated, enabling the prediction of flood characteristics such as volume, velocity, and depth in different river sections and conditions, as well as their impact on riverbeds and surrounding flood-prone areas.
In this research, a 25-year return period flood in the Kardeh River was simulated using HEC-RAS 2D software. Sensitivity analyses indicated that the hydraulic model, HEC-RAS, is sensitive to factors including Manning's roughness coefficient, computational network dimensions, and solution methods for governing flow equations. Results revealed that the model performs better in flood simulation using the dynamic wave equation method compared to the kinematic wave method. Evaluation of observed and simulated hydrographs within the study domain's lower range yielded statistical indices of 5, 0.95, and 0.93 for percentage error, coefficient of determination, and Nash-Sutcliffe coefficient, respectively, using the dynamic wave method, and 34, 0.96, and 0.64 for the kinematic wave method.
For riverbed management, flood hazard zoning was implemented, identifying the primary river path as the area of highest risk due to its greater depth, steeper gradient, and lower vegetation coverage. To prevent flood ingress into agricultural, orchard, and nearby village areas, a hybrid system (levees and flood barriers) was proposed for multiple river segments to mitigate floods and subsequently reduce associated damages.