Determining the rating curves in asymmetric compound channels

Generally, natural open channels have sections in which by increasing the water level, the crosssectional area will be increased considerably. These sections have consisted of relatively wide floodplains. In compound channels with asymmetric cross-sections, the hydraulic behavior of the flow would be complicated. Rating curves estimation in compound channels is one of the most critical issues of river engineering. In the current study, a new approach based on the concept of the crosssectional isovel contours is introduced for the estimation of rating curves in compound channels. To extract the exponent values of the governing parameters, minimization approach is used to the difference between the observed and estimated data. In this method, in order to set up the rating curves in various cross-sections, it is only requisite to have the flow information at a reference water level. The results show that the proposed method has a good accuracy for predicting rating curves in asymmetric compound channels even in compound channels with different floodplain levels.