Coupling Green-Ampt and Saint-Venant Equations for Estimating of Transmission Losses during Flood Routing in Rivers

Volume of flooding flow volume in ephemeral streams decreases due to evaporation as well as the channel wall and bed penetration. This process is known as transmission losses. In this study, a model is developed to estimate the transmission losses in irregular sections of rivers, in which a finite difference scheme is used to solve Saint-Venant equations. In this model, for estimating the transmission losses, the Green-Ampt equation is coupled with Saint-Venant equations. After verification of model, the transmission losses at Gharesoo river with 18 KM length and 60 cross sections after 65 hours flood event is evaluated. The results showed that the Green-Ampt equation can predict transmission losses with good accuracy. Using model the transmission losses equal to 1400000 cubic meters is computed which is 2.75% of input flood volume to the reach. Also this model is enabled to evaluate the infiltration rate and cumulative infiltration depth.