Flood Routing Using Models Based on Input and Output Data

Abstract

Convolution or linear-systems methods for simulation have not received much attention in hydraulics, although well-known in hydrology. They can be conveniently used in the common situation where stage hydrographs from two river measuring stations are known. No details of river geometry or resistance data are required. The principal problem is to determine the propagation characteristics of the river reach, for which optimisation methods are shown to be convenient and can be simply extended to cases with several inflows. Using water level has advantages: it is a quantity that is usually measured, no rating curves are necessary, unsteadiness is not a problem, the range of variation of level is less than that of the flow, so the equations are more valid, and it is the effects of high water level that cause flooding anyway. The methods are shown to be not as accurate for large floods, but then other simulation methods require physical data that may not be well known. As a simple and stable computational tool, the methods examined here might have a role to play.