Some hydraulic structures and phenomena, including compound channels, must be studied in relation to open channel flow. Despite the fact that the primary channel and watersheds share a similar degree of roughness, estimating discharge in composite channels with mainstreams and flood plains has proved tricky. The flow discharge for a compound channel with different roughness in the primary and flood plain channels has been studied, and the results computed experimentally using horizontal division level have been compared with those predicted using dimensional analysis and an adaptive neuro-fuzzy inference system. The results show good agreement between experimental and numerical for discharge calculation according to root-mean-square error, MARE, R 2, SI, and Nash–Sutcliffe efficiency, with a percentage error not exceeding ±5%.

Weirs are hydraulic obstructions constructed across an open-channel flow causing a rise in water which is useful to convert water to the channels upstream as well as using these structures as a measuring device. There are different types, and a sharp-crested weir is one of them. Local scour downstream hydraulic structures are one of the most critical problems affecting their safety and stability. Many studies conducted to prevent these facilities from collapsing, but the effect of adding a solid apron downstream weir still need deep studies. The current study included a survey of scour reduction downstream sharp-crested weir using a solid apron consisting of three different lengths, four different discharges, and sand bed material to calculate the maximum depth and length of scour hole when using an apron solid. The results proved that the depth and length of the scour hole are reduced to 19.3% and 27.7%, respectively, when an apron solid is used. Two empirical equations were found to determine the maximum depth and length of the hole with a coefficient of determination are 0.892 and 0.804, respectively.

Several studies indicate that using hydraulic structure results in some adverse effects that affect the stability of these structures, including scouring the floor. Many researchers resorted to using defensive means to reduce the flow’s speed and energy as much as possible. One of these means is the use of screen walls. Therefore, the current study focused on reviewing different types of research that dealt with the help of screen walls by changing the location of the screen and geometric shape, such as the diameter of the holes, thickness of the screen wall, porosity, changing the geometric arrangement of the gaps such as the square, triangle and hexagon, as well as the use of a screen inclined at a certain angle, use of triangular meshes and use Artificial intelligence programs to simulate and compare results.