Hydrological problems of flash floods and the encroachment of wastewater affecting the urban areas in Greater Cairo, Egypt, using remote sensing and GIS techniques

Hanaa A Megahed,Mohammed A El Bastawesy

doi:10.1186/s42269-020-00442-5

Abstract

BackgroundThis paper discusses the hydrological problems assessment of flash floods and the encroachment of wastewater in selected urban areas of Greater Cairo using remote sensing and geographic information system (GIS) techniques. The integration of hydrogeological and geomorphological analyses with the fieldwork of drainage basins (Wadi Degla) hosting these urban areas endeavors to provide the optimum mitigation measures that can be feasibly taken to achieve sustainability of the urban areas and water resources available.ResultsLandsat 5 and Sentinel-2 satellite images were obtained shortly before and after flash flood events and were downloaded and analyzed to define the active channels, urban interference, storage areas, and the natural depressions response. The quantitative flash flood estimates include total GSMap meteorological data sets, parameters of rainfall depths from remote sensing data, active channel area from satellite images, and storage areas that flooded. In GIS, digital elevation model was used to estimate the hydrographic parameters: flow direction within the catchment, flow accumulation, time zone of the catchment, and estimating of the water volume in the largely inundated depressions.ConclusionsBased on the results obtained from the study of available satellite images, it has been shown that there are two significant hydrological problems, including the lack of flash flood mitigation measures for urban areas, as the wastewater depressions and sanitary facilities are dotting in the downstream areas.

Highlights

This paper discusses the hydrological problems assessment of flash floods and the encroachment of wastewater in selected urban areas of Greater Cairo using remote sensing and geographic information system (GIS) techniques
The land cover map obtained from satellite images (Fig. 6) shows that drastic change in land cover has occurred within the catchment due to the urban expansion of New Cairo over the expanse of surrounding barren areas
These changes will affect the runoff coefficients and the flash flood magnitudes delivered to the main conveying channels

Summary

Introduction

This paper discusses the hydrological problems assessment of flash floods and the encroachment of wastewater in selected urban areas of Greater Cairo using remote sensing and geographic information system (GIS) techniques. Populated areas in dryland regions have experienced great difficulties in better managing inhabited lands, which are usually under severe hydrological stress (Arzani 2010; El Bastawesy et al 2013a, b). According to the hydrological systems, surface water supplies to urban areas can be a significant factor limiting the degree of land use (El-Baz et al 2000; Rubin 1991; Tooth 2000). The most suitable locations for urban development are the low relief areas of alluvial fans, wadi beds, and piedmonts (Dunne 1991). Notwithstanding, these areas in drainage basin outlets usually contain potential aggregate and row deposit supplies for building materials as well as groundwater resources fed by periodic rainstorms and flash floods (Blair and McPherson 1994).

Methods

Results

Conclusion