A spatial and integrated flood risk diagnosis

Abstract

Purpose The purpose of this paper is to identify vulnerable areas for flood hazard and to analyze stakes exposed in touristic valley of Morrocan mountains. The three goals are: methodological (low-cost diagnosis without starting data), operational (to show the risk and identify avenues of prevention in Ourika) and incentive (to reproduce this on other sectors in Morocco). Design/methodology/approach The vulnerability of three areas of the Ourika valley (the most frequented) was assessed by a hydro-geomorphological study, human frequentation surveys and risk indices at the building scale. Findings Surveys carried out in the field allowed the identification of areas with high risk, the evaluation of the buildings’ vulnerability and the frequentation of the valley. Evacuation plans, allowing easy access to potential refuges in case of flood, were finally proposed. Originality/value The reproducible, inexpensive and relevant nature of the approach (integrated and spatialized) helps in decision making and facilitating dialogue for prevention.

Flood Susceptibility Assessment through Statistical Models and HEC-RAS Analysis for Sustainable Management in Essaouira Province, Morocco

“…-Drainage density: The time of concentration of runoff and the probability of flooding are linked to the drainage density in an area. Previous studies [67,[100][101][102] have established that the volume of flow accumulation from upstream to downstream in the river basin is affected by drainage density. A higher drainage density indicates a greater surface runoff, which in turn increases the likelihood of flooding [103].…”

An Integrated Multi-Risk Assessment for Floods and Drought in the Marrakech-Safi Region (Morocco)

“…Ezzine et al (2016) report that between 1982 and 2015 there have been at least 17 flood events that have caused severe human and material losses in the region, with at least one event per year since 2008. Arguably, the most devastating flood event occurred on August 17th 1995, when an exceptionally strong flash flood in the Ourika Valley (located in the High Atlas), claimed the lives of more than 200 people (Bennani et al, 2019). Figure 1 shows the main geographical features of the region, namely its land use-land cover and administrative divisions (A), and the superimpositions between flood and drought hazards extents and a set of assets of interest, namely population (B), road infrastructure (B), rain fed farmlands (C), and irrigated farmlands (D).…”

“…In the case of a 100-yr flood event, the model used in this analysis shows that this type of flood can potentially cause major effects on the growing urban settlements in the floodplains of the major watercourse of the region. However, the most destructive floods in the region have predominantly originated from intense precipitations occurring locally into narrow basins with extremely steep slopes, thus producing exceptionally fast accumulation of rainfall and large discharge (Daoudi and Saidi, 2008;Bennani et al, 2019;Louodyi et al, 2022). Furthermore, flood exposure results is also conditioned by the population distribution model used: in particular, Smith et al (2019) warn that the use of the WorldPop dataset might generate overestimation of flood exposure, especially in rural areas, due to the fact that in the model built-up areas are not masked: this means that even pixels that do not belong to areas classified as urban will receive a population prediction, albeit very small, and no pixel will receive a value of zero (equal to absence of population; Smith et al, 2019).…”

Challenges in flood modeling over data-scarce regions: how to exploit globally available soil moisture products to estimate antecedent soil wetness conditions in Morocco

“…1), with an altitude ranging from 1027 to 4167 m and an area of 225 km 2 . The climate in the basin is semiarid and strongly influenced by altitude, with a mean annual precipitation of 732 mm, including 30 % as snow in altitudes above 2000 m (Boudhar et al, 2009). The geology is characterized by volcanic formations that are considered impermeable in the highest elevation areas, while the lowest elevation areas are made of granites with clays and marls.…”