Flash Floods in the Guelmim Area/Southwest Morocco–Use of Remote Sensing and GIS-Tools for the Detection of Flooding-Prone Areas

Abstract

The violent storms of 22-30 November 2014, resulted in flash floods and wadi floods (rivers) in large parts of Southern Morocco, at the foot of the Atlas Mountains. The Guelmim area was the most affected part with at least 32 fatalities and damages due to inundations. The flooding hazard in the Guelmim region initiated this study in order to investigate the use of remote sensing and geographic information system (GIS) for the detection and identification of areas most likely to be flooded in the future again due to their morphologic properties during similar weather conditions. By combining morphometric analysis and visual interpretation based on Landsat 8 satellite data and derived images such as water index (NDWI) images, areas with relatively higher soil moisture and recently deposited sediments were identified. The resulting maps of weighted overlay procedures, aggregating causal, morphometric factors influencing the susceptibility to flooding (lowest height levels, flattest areas), allowed for the distinguishing of areas with higher, medium and lower susceptibility to flooding. Thus, GIS and remote sensing tools contribut to the recognition and mapping of areas and infrastructure prone to flooding in the Guelmim area.

Remote Sensing and GIS Contribution to a Natural Hazard Database in Western Saudi Arabia

“…One of the first steps towards the assessment of the different geohazards is susceptibility analysis and mapping. The interactions and dependencies between different causal and preparatory factors influencing the susceptibility to natural hazards can be visualized and weighted step by step in a GIS environment [32,33]. The susceptibility analysis and maps comprise the potential location of the most affected areas.…”

“…In order to support the preparedness to inundations, DEM data can be used to create maps indicating those areas prone to flash floods, due to their morphometric properties. A weighted overlay procedure can be carried out for the detection of areas with higher susceptibility to flash floods by extracting causal/preparatory factors and, then, by aggregating these factors in the weighted overlay-tool of ArcGIS [32,33]. The susceptibility model represents a methodological approach to facilitate the spatial identification of flood zones.…”

“…The second step extracts the sink depths in these areas by differencing the maps between the sink-filled ("depressionless" DEM) and original DEM. The difference image highlights the different depressions [32]. This approach was carried out based on SRTM, Aster and ALOS PALSAR DEM data, comparing the results.…”

Coastal Risk and Water Flow Analysis in Eastern Algeria (Western Mediterranean)

“…The weighted overlay approach in ArcGIS contributes to the detection of those coastal areas in the Jijel and Bejaja regions that are prone to flooding due to their morphometric disposition such as river mouths and flat lowlands, thus, providing a basic flooding susceptibility map. As this GIS approach has shown promising results in comparable areas [28][29][30][31], it might be useful here as well.…”

Natural Hazard Assessment in Western Saudi Arabia using Remote Sensing and GIS Methods

“…Seiches are typically caused when strong winds and rapid changes in atmospheric pressure push water from one side of the Red Sea to the other. When the wind stops, the water rebounds to the other side of the enclosed area [23]. The water then can continue to oscillate back and forth for hours or even days.…”