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University of Reading (2005)

Development of GIS based hydrological model for hyper-arid catchment of Wadi Haymour

Bastawesy, Mohammed El.

Titre : Development of GIS based hydrological model for hyper-arid catchment of Wadi Haymour

Auteur : Bastawesy, Mohammed El.

Université de soutenance : University of Reading

Grade : Doctor of Philosophy (Ph.D.) : 2005

This project uses GIS techniques for hydrological modelling of a dryland catchment Eastern Desert of Egypt. Wadi Haymour is an ungauged large catchment of 1937 km2, which is known to exhibit severe flash floods. This project introduces a new technique to simulate spatially and temporally variable active channels areas and transmission losses. Initially, potential runoff volumes generated on hillslopes were routed to channels located within each time- area zone, and transmission loss was calculated based on the infiltration rate and the active channel areas in the first hour. For every hour the flow volumes delivered into a time-area zone was transmitted downstream into the next time-area zone, and transmission losses were subtracted over the given active channel area. The routing process was continued until the flow from the farthest point in catchment reached the outlet. The routing time intervals could be shorter, depending on rainfall duration, catchment size and temporal and spatial variations of infiltration rates. A sensitivity analysis was conducted to investigate the influence of model component on hydrograph characteristics. A set of interpolated DEMs of 20, 50, 90 along with a 90 m resolution SRTM DEM were used to extract drainage networks and to derive slope for overland flow velocity calculation. The DEM source has a more significant influence on hydrograph attenuation and duration than DEM resolution. Furthermore, the influence of Manning roughness coefficient and channel geometry were found to be far more pronounced than DEM resolution. The time-area zones, which represent the potential runoff once the rainfall is known, does not necessarily define the hydrograph. Initial flow volumes produced at each zone will continuously be reduced downstream due to transmission loss and consequently the total hydrograph lag time is altered for high transmission loss rates and or/prolonged rainfall events

Présentation : EThOS (UK)

Accès au document : Proquest Dissertations & Theses

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