RN-8 : Hydrologic flood routing including data requirement

Abstract

Flood routing is used to simulate flood wave movement through river reaches and reservoirs. There are two types of flood routing methods used in practice viz., hydraulic flood routing and hydrologic flood routing. Hydrologic flood routing uses the continuity equation in lumped form and some relationship between discharge and storage within the reach. This report reviews, the various hydrologic flood routing methods available in literature including. the two parameter models which incorporate the Muskingum method, lag and route method, Kalinin-Milyukov method, diffusion analogy method, modified Puls method, and working R and D method; the three parameter models which incorporate diffusion added with lag model, multiple Muskingum method and three parameter gamma distribution etc. The linearized St.Venant's equations model applied to wide rectangular channels, the multiple linearization flood routing model, and the simple non-linear model are also reviewed. A broad discussion on the relationship between some of the hydrologic flood routing methods and the basic St.Venant's equations describing the one dimensional flow in channel is made. The advantages of the hydrologic flood routing methods over the hydraulic flood routing methods are described. The limitations of the hydrologic flood routing methods for their inability to take into account the back water effects and discontinuities in the water surface such as jumps or bores are considered. The data requirements of the hydrologic flood routing methods are indicated.