Investigating the causes of scouring downstream of stilling basin of Shohada diversion dam and proposing suitable solutions to control it

Shohada diversion dam was constructed on the border of agricultural lands of Behbahan plain (Khuzestan province, Iran) to divert the water of the Maroun River. This dam has a concrete-soil composite. The concrete part consists of an ogee spillway, a stilling basin, and two intake channels and sediments on the right and left sides. The height of the dam is 12.2 meters and its spillway length is 150 meters. The dam has a sloping basin and its capacity is 22 m3/sec. The longitudinal slope of this basin is 1 to 5 (vertical: horizon). The studies have shown that parts of downstream of the stilling basin are being eroded and scoured. Unless controlled properly, this will continue and might lead to the destruction of the basin or the main structure of the dam. Most of the stilling or apron basins used in the previous studies are horizontal and smooth, and no research has been conducted on scouring downstream of sloping basins so far. Therefore, the purpose of this research is to explore the causes of scouring downstream of the Shohada dam's stilling basin and its controlling factors to finally provide an appropriate strategy to prevent its spread.