Assessment of Flood Mitigation Strategies: A Case Study of the Aït Athmane Center in the Errachidia Region

Abstract

The development of impoverished and marginalized communities is being increasingly jeopardized by the risks associated with climate change. Extreme weather events, like floods, can impact infrastructure, ecosystems, agriculture, water, and other vital sectors. Our study focuses on the flood risk in Aït Athmane, located 28 kilometres north of Errachidia, Morocco. This area is particularly vulnerable to flooding and overflows from the Ziz Wadi tributary, which passes through the territory of Aït Athmane. The specific objectives of this study are to assess the effects of flooding in this area and to propose various adaptation strategies. The methodology involved processing GIS data for the basin's hydrological study, statistically analyzing the maximum daily rainfall at the “Foum Tillicht” rainfall station using HyfranPlus software, and estimating peak flow using various empirical formulas. We then used the 'HEC-RAS' hydraulic modeling program to perform a hydraulic simulation, an essential step in understanding these values for Aït Athmane Wadi, a tributary of Ziz Wadi. GIS software was used to create the maps, which were superimposed to identify locations vulnerable to flooding. The findings indicate that, for varying return periods, flows range from 60.13 m³/s to 92.69 m³/s, with a concentration-time of 125.55 minutes. The hydraulic study indicates an overflow risk, endangering nearby residents and their crops. In certain areas, these floods can reach three meters. Numerous strategies have been identified and proposed to mitigate the effects of this significant risk. These primarily involve simple mechanical adjustments such as constructing gabion weirs, raising retaining walls along the Wadi's banks, and creating crossing structures.