Flash flooding hazard assessment, modeling, and management in the coastal zone of Ras Ghareb City, Gulf of Suez, Egypt

Abstract

The assessment of flash flood hazards in the coastal zone of Ras Ghareb City (RGC), Red Sea, Egypt, was accomplished through the use of GIS tools and the spatial multi-criteria approach. The presented work aims to assess, integrate, and generate potential flash flood hazard maps. The analytic hierarchy process was utilized to calculate weights of hazard and vulnerability of flash flood controlling factors and their parameters such as topographical, geological, and hydrological factors. In addition, the risk degree of each specific basin and its sub-basins is estimated by combining standardized parameter values. Despite its location in an arid region, the basin may receive a large amount of rainwater, which can cause flash floods at the basin's outlet. Recently, flash flooding took place in the coastal region of RGC in October 2016 and September 2020, resulting in the loss of many human lives and catastrophic effects on local infrastructure and surrounding environments. According to reports from Hurghada, Red Sea Governorate, the RGC experienced exceptional flooding that exceeded 120 million cubic meters as a result of 51 mm of rainfall. Based on the remote sensing satellite data such as Aster Digital Elevation Model (GDEM) and the GIS tools, the basin and sub-basin drainage patterns were delineated and compared with reference topographical map sheets of a scale of 1: 50,000. The sub-basins have been isolated and morphometrically studied to determine vulnerability to flash flooding. In addition, the flash flood threat model was developed using geoprocessing tools provided by ArcGIS software to incorporate all contributing factors spatially. The flash flood risk in the Ras Ghareb (RG) basins and their sub-basins has been identified and classified into three classes (high, medium, and low hazard degree). High and moderate flood-risk basins require comprehensive studies to introduce measures to protect certain areas from flood danger. Finally, the GIS and the spatial multi-criteria analyses were effective ways to carry out a flash flood management system in order to support the decision-makers by recommendations to conserve and mitigate the possible flash flood hazards in the study areas.

Assessment of geological hazard susceptibility based on remote sensing images

“…DEMs are a commonly used data type for mapping large-scale movements, faults, floods, and topography of coastal areas [25]. In flash flood studies, DEMs are considered a valuable data source for obtaining information on various fundamental parameters of the terrain [26]. Moustafa et al used a DEM reflecting regional surface conditions when mapping the sensitivity of fault segments within the Egyptian continent (possible fault zone maps) [14].…”

“…They used the trained back-propagation weights to calculate the landslide susceptibility index (LSI) [38].In order to identify the key factors contributing to landslide hazards, Lin et al used the CF method to analyze eight geoenvironmental factors in the area [39]. After completing experiments to assess flash flood outbreaks, Arnous et al concluded that an enhanced understanding of the mechanisms of interaction between topographic features and extreme meteorological conditions could lead to a better understanding of the causes of flood outbreaks [26]. Ali et al concluded that there are three primary conditions for the origin of a mudslide: slope, water source, and erodible unconsolidated sediments, which can be used as a vital source of evaluation factors for assessing mudslide hazards [40].…”

Revealing the geomorphic parameters of neotectonics based on geological and seismic data at Wadi Beda basin, NW Gulf of Suez, Egypt

“…Gebel Akheider and downstream of Wadi Akheider 3. Gebel El-Ramliya and downstream of Wadi El-Noqra Based on the weighted basin and channel geomorphometric parameters (circularity, basin length, basin area, basin perimeter, bifurcation ratio, drainage density, and stream frequency), the Wadi Beda Main Basin was given a moderate rank of flood potentiality (Arnous et al 2022). This moderate rank indicates that Wadi Beda Main Basin is not capable to collect high quantity of runoff water, and hence, a low quantity of water moves out the basin, which is lowrisk Basin.…”

Flood susceptibility assessment on the proposed high-speed train track Qena-Hurghada-Safaga (QHS), Egypt

“…Selected criteria (Choudhury et al, 2022) (1) elevation, (2) aspect, (3) curvature, (4) slope, (5) land cover, ( 6) and ( 7) normalised difference vegetation/water index (NDVI) (NDWI), (8) distance to roads, (9) distance to rivers, (10) Rainfall, (11) TPI, and ( 12) TWI (Serdar et al, 2022) (1) slope, (2) groundwater depth, (3) distance to streams, and (4) land use/land cover (LULC) (Arnous et al, 2022) (1) morphometric variables, (2) runoff characteristics, (3) units of lithology, (4) slope, (5) elevation, (6) structure lineament, and (7) rainfall volume (Msabi et al, 2021) (1) geology, (2) accumulation of flow, (3) slope, (4) LULC, (5) density of drainage, (6) stream order, (7) elevation, and (8) soil It is crucial to keep in mind that various factors have varying roles depending on the local natural conditions in each location (Mudashiru et al, 2021;Yaseen et al, 2022). For example, the study area is a dry, sand-dominated desert.…”

“…A simplified statistical technique is used to estimate peak discharge and peak time based on the correlation between parameter values and runoff likelihood (Pradhan et al 2010). We applied the same procedures as in the first criterion to define the flood susceptibility using cumulative runoff parameters, where the surface velocity, peak discharge, and time concentration characteristics are categorised into five groups based on risk degree probability (Arnous et al, 2022) (Fig. 12).…”