Dynamic Flood Routing with Explicit and Implicit Numerical Solution Schemes

Abstract

A characteristics-based, upwind, explicit numerical scheme is developed for one-dimensional (1D) unsteady flow modeling of natural rivers and implemented into the U.S. National Weather Service (NWS) FLDWAV model in combination with the original four-point implicit scheme. The new explicit scheme is extensively tested and compared with the implicit scheme. The study shows that the new explicit scheme provides improved versatility and accuracy in some situations, such as particularly large dam-break waves and other unsteady flows with near critical mixed-flow regimes. A technique for implicit-explicit multiple routing is introduced to incorporate the advantages of using both schemes within an application of the FLDWAV model.