Effect of choice of routing model on extreme flow statistics

Abstract

Abstract The problem considered is that of the trade-off between complexity and accuracy of flood routing models and methods of determination of extreme flow statistics. A system is analyzed consisting of a channel reach, with a set of input flood waves which are routed through the reach by using a flood routing method. It is desired to evaluate the consequences for design of the error which is introduced if, instead of the complete St. Venant (SV) equations, the Kalinin-Milyukov (KM) model is used to calculate the outflow from the reach. This problem is investigated by means of an example. As a standard, the routing by the complete SV equations is used. It is found that the use of the linear KM method introduces an error as compared to the complete SV equations which is smaller than the uncertainty caused by the choice of extreme value distribution. As a consequence, the results from the KM method are found to be as acceptable for design as the results obtained from the SV equations.