Abstract
Digital elevation models (DEMs) are the cornerstone for hydrological and geomorphological modeling. Herein, two Nile-tributary catchments (Wadi Al Rishrash and Wadi Atfeh) in Egypt are selected to examine the contribution of different DEMs to the accuracy of hydrological and geomorphological analyses in the hyper-arid Sahara. DEMs sources include: Advanced Land Observing Satellite-1 (ALOS) Phased Array type L-band Synthetic Aperture Radar (PALSAR) (12.5 m resolution), ALOS World 3D with 30 m resolution (AW3D30), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER DEM with 30 m resolution) and the Shuttle Radar Topography Mission (SRTM with 30 and 90 m resolution), in addition to topographic map-derived DEM (90 m resolution). Using a hypothetical uniformly-distributed 10 mm rainfall event, the estimated parameters, including: flow duration, time to peak and peak discharge rates, are almost similar for the different DEMs and thus technical aspects related to sources and resolutions of the datasets impose insignificant control on quantitative flash-flood analyses. Conversely, variations in geological and geomorphological characteristics of the catchments show more significant control on the hydrograph magnitudes as indicated by the different parameters of the two catchments. These findings indicate that understanding the geological and hydrological evolution of the catchment is essential for integrated management strategies of floods especially in the Saharan–Arabian deserts and in similar conditions of hyper-aridity and scarce in situ data worldwide.
Highlights
Introduction iationsDryland hydrological modelling usually incorporates multiple data sources, processing algorithms and field measurements to estimate quantitative parameters, which are being determined according to the identified sets of objectives
Variations in geological and geomorphological characteristics of the catchments show more significant control on the hydrograph magnitudes as indicated by the different parameters of the two catchments. These findings indicate that understanding the geological and hydrological evolution of the catchment is essential for integrated management strategies of floods especially in the Saharan–Arabian deserts and in similar conditions of hyper-aridity and scarce in situ data worldwide
This paper aims to examine the hydrological and environmental aspects of flash floods delivered to the northern sector of the Nile Valley in Egypt from two main watersheds, namely Al Rishrash and Atfeh catchments under conditions of hyper-aridity and scarce in situ data
Summary
Dryland hydrological modelling usually incorporates multiple data sources, processing algorithms and field measurements to estimate quantitative parameters, which are being determined according to the identified sets of objectives. The depth distributions and patterns of flash floods currently receive a great deal of attention, due to the notable increase in the frequency and magnitude of flash-flood events, and the developed negative socio-economic consequences [1,2,3]. The efficiency of flashflood management strategies are dominated to large extents by the quality of available data, field measurements and verifications [4]. Topographic maps have been used for decades as the primary source to derive hydrographic and hydrologic elements. Scale and data consistency are among the main problems that delimit the capabilities of traditional topographic maps in the hydrological modelling [5,6]
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