Placement of flood retention ponds and design of river flood diversion system in order to protect the floodplain, case study: Gorganrood River

In this research, the location of the temporary flood storage sites and the design of the river flood diversion system have been carried out using one-dimensional and two-dimensional hydraulic modeling of the flood and considering the structural and hydraulic design criteria of diversion dams. An important portion of the Gorganrood River, which includes the downstream reach of the Golestan Dam to the connection to the Caspian Sea, has been selected as a case study, and the effect of flood diversion on the peak discharge and flood level of the most vulnerable flood prone areas including the cities of Aqqala and Gomishan, has been studied. Locating the diversion and storage locations has been done using Flo-2D, HEC-RAS and SWMM models, and then, according to the criteria of cost and efficiency, suitable locations of flood storage sites have been determined.  Finally, the separate and combined performance of these dams on the flood features of the river at the damage points during 4 important rainfall events have been estimated. The results showed that if flood diversion systems are used, the peak flow of the flood at the entrance to Aqqala and Gomishan city will decrease by 16.35 and 22.15% on average.