Improved Estimates of Kinematic Wave Parameters for Circular Channels

Abstract

The momentum equation in the kinematic wave model is a power-law equation with two parameters. These parameters, which relate the discharge to the flow area, are commonly derived using Manning's equation. In general, the values of these parameters depend on the flow depth except for some special cross sections. In this paper, improved estimates of the kinematic wave parameters for circular channels were developed using the kinematic sensitivity indicator. Using this indicator, the parameters were mathematically derived nearly independent of the flow depth for two cases: constant and variable Manning's roughness coefficients. The proposed parameters were estimated for a practical range of water depth levels and were verified using an approximate method. The results showed that the proposed parameters are more accurate than existing parameters in estimating the discharge for circular channels. The proposed parameters also improved the estimate of travel time in circular channels, which is of significant importance in drainage design.