Elementary discharge coefficient of sharp crested rectangular side weir located in 180◦ channel bend in free flow conditions

Side weir is one of the important structures in irrigation and drainage networks. The main problem to study the hydraulic of flow in this structure is determination of water level profile along the weir and diverted flow discharge. In the present study, discharge coefficient of free flow of side weir located in various parts of the 180 degree channel bend is investigated experimentally. Also with considering the variation of water level along the weir and numerical solution of dynamic equation of spatially varied flow over side weir, the elementary discharge coefficient is related to Froude number, side weir location and the ratio of weir height to head of water. In order to compute the exponents and coefficients of relation, the genetic algorithm was used. The results showed that by using the elementary discharge coefficient, the water level along the weir and diverted flow discharge can be estimated precisely.