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Accueil du site → Doctorat → Royaume-Uni → 1993 → A physically-based model for the prediction of flood hydrographs in arid zone catchments

University of Cambridge (1993)

A physically-based model for the prediction of flood hydrographs in arid zone catchments

El-Hames, A S.

Titre : A physically-based model for the prediction of flood hydrographs in arid zone catchments.

Auteur : El-Hames, A S.

Université de soutenance : University of Cambridge

Grade : Doctor of Philosophy (Ph.D.) : 1993

Résumé
Studying flood hydrology in warm low-latitude arid and semi-arid environments is an interesting and challenging subject due to the difficulty of data acquisition, given the intermittent and often extreme nature of flood events. The low population density, and therefore inaccessibility of some of these areas makes it a difficult task for investigators to collect reliable information, especially in the absence of previous detailed work. However, increasing developments pressure involving irrigated agricultural expansion and urban/industrial development place demands on hydrologists for reliable methods of flood prediction. Taking advantage of development in physically-based models is one solution to this problem. In this work, flood magnitude and hydrograph behaviour are investigated in arid regions by employing modelling techniques. Different models for the evaluation of the main hydrological parameters such as the infiltration rate, the rainfall excess, overland flow routing, channel routing, and transmission loss have been developed. In the first model the Richards’ equation is used to account for infiltration rate. This equation has been solved by applying a numerical finite difference solution based on the Crank-Nicholson method in one dimension. Once the infiltration rate has been calculated, excess rainfall can be estimated. The excess rainfall can then be routed over hillslope surfaces by applying the kinematic wave theory. This theory was utilised here using a Taylor expansion and the Lax-Wendroff finite difference scheme. This forms the overland flow routing model in this research. The resultant flow at the base of hillslopes is accumulated and routed through the channel network of a selected catchment. This part of the study was developed by solving the full shallow water equation, implementing a second order approximation of Taylor’s expansion in one dimension. The infiltration model was used to simulate transmission loss in to wadi bed sediments during the process of downstream hydrograph translation. The three basic sub-models were coupled together to form one integrated model. This model was finally applied in a selected semi-arid area located in the south western region of Saudi Arabia. Outputs of this model were compared with observed floods in this study catchment.

Mots clés : Rainfall runoff models Hydrology

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