An integrated, physically based model for arid region flash flood prediction capable of simulating dynamic transmission loss

Abstract

Abstract:This paper outlines a physically based model developed for prediction of both arid region¯ash¯oods and associated transmission loss. It is based on coupling numerical solutions of the St Venant equations and the kinematic wave equation for channel and overland¯ow routing, respectively, with the Richards' equation for the determination of in®ltration. These hydrological components are integrated in one comprehensive model for the above-mentioned purposes. The robustness of the model and its components have been tested and it has then been applied to a medium-size catchment in an arid region. The results indicate that reasonable simulations can be achieved with a minimum of calibration, but point to problems of representing input rainfall conditions with the necessary time and space resolutions. #

A channel transmission losses model for different dryland rivers

“…However, monitoring of surface flow in dryland rivers is difficult in many regions, due to often low population density, the remoteness of hydrological stations and the inherent short duration of runoff (El-Hames and Richards, 1998). Moreover, extreme climatic variation from year to year, especially variation in annual precipitation, increases the problems of constructing probabilistic models (El-Hames and Richards, 1998). In this context, process-oriented hydrological models parameterized from field measurements and geo-database maps may be the most suitable or indeed the inevitable tool to predict both streamflow and channel transmission losses (e.g.…”

“…In this context, process-oriented hydrological models parameterized from field measurements and geo-database maps may be the most suitable or indeed the inevitable tool to predict both streamflow and channel transmission losses (e.g. El-Hames and Richards, 1998;Lange et al, 1999;Gheith and Sultan, 2002;Lange, 2005;Costelloe et al, 2006;Morin et al, 2009).…”

“…Therefore, unsaturated flow through the alluvium, together with in-channel variable ponding depth, hampers a transmission losses model for disconnected losing streams. An extra difficulty might be the existence of an underlying stratified alluvium, which can often be found in dryland riverscapes (Parissopoulos and Wheater, 1992;El-Hames and Richards, 1998).…”

“…Pressure-head-based Richards' equation enables us to model unsaturated flow through the alluvium considering both in-channel variable ponding depth and stratified alluvium as done by El-hames and Richards (1998). This might be the most physically comprehensive approach to model channel transmission losses for disconnected losing streams.…”

“…This might be the most physically comprehensive approach to model channel transmission losses for disconnected losing streams. However, its application can require a long processing time to simulate large-and meso-scale catchments (El-hames and Richards, 1998) and large sets of alluvium data, which are usually not available, especially in dryland environments. Alternatively, some authors have used constant infiltration rates in the channels (Lange et al, 1999;Morin et al, 2009), neglecting both in-channel variable ponding depth and unsaturated flow.…”