Numerical Modeling of Looped Rating Curve in Irregular and Regular Channels: A Case Study of Qaresou River, Iran

In the field of hydrology, the flood routing at rivers is of great importance and modeling looped stage-discharge curve which occurs due to flooding in rivers has attracted the attention of many researchers. However, unfortunately, very few studies have been done on this issue. In this study, using the numerical solution of Saint-Venant’s equations, a computer model is developed in order to predict the looped rating curve in unsteady conditions at regular and irregular channels (Qaresoo River), and the effects of changes in parameters such as Manning roughness, longitudinal slope, lateral slope on looped rating curve are investigated. The results showed that with increasing longitudinal slope, the looped area trends towards zero and flood wave approached to the kinematic wave. The looped area increases as the bed roughness increases and the gap between the rising and falling scale increases. Moreover, based on the area of the loop of the rating curve, it can be determined whether or not the flood waves are dynamic, kinematic or diffused.