Hydrologic Routing of Flow in Arid Ephemeral Channels

Abstract

Hydrographs of ephemeral streams in an arid region usually decrease significantly in magnitude, downstream, unless they are augmented by tributary flows. Estimation of outflow hydrographs from a channel reach is essential for the development of water-resources systems. A hydrologic-flow-routing technique for arid ephemeral channels is developed. The hydrologic-routing equations for the movement of flood waves are modified by the inclusion of a nonlinear volumetric transmission loss rate term, which is empirically estimated from the observed inflow-outflow data for a channel reach. The predicted outflow hydrographs match better with the observed than the outflow hydrographs generated through the lumped regression model for ephemeral channels. The hydrologic-flow-routing technique may also be used for ungaged channel reaches through parameterization.