Debilitating floods in the Sahel are becoming frequent

Nadir Ahmed Elagib,Islam Sabry Al Zayed,Suhair A.Gayoum Saad,Mohamad Ibrahim Mahmood,Mohammed Basheer,Andreas H Fink

doi:10.1016/j.jhydrol.2021.126362

Nadir Ahmed Elagib, Islam Sabry Al Zayed + Show 4 more

Open Access

https://doi.org/10.1016/j.jhydrol.2021.126362

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Abstract

Despite the long-lasting and widespread drought in the Sahel, flood events did punctuate in the past. The concern about floods remains dwarf on the international research and policy agenda compared to droughts. In this paper, we elucidate that floods in the Sahel are now becoming more frequent, widespread, and more devastating. We analyzed gridded daily rainfall data over the period 1981–2020, used photographs and satellite images to depict flood areas and threats, compiled and studied flood-related statistics over the past two decades, and supported the results with peer-reviewed literature. Our analysis revealed that the timing of the maximum daily rainfall occurs from the last week of July to mid-August in the Eastern Sahel, but from the last week of July to the end of August in the Western Sahel. In 2019 and 2020, flash and riverine floods took their toll in Sudan and elsewhere in the region in terms of the number of affected people, direct deaths, destroyed and damaged houses and croplands, contaminated water resources, and disease outbreaks and deaths. Changes in rainfall intensity, human interventions in the physical environment, and poor urban planning play a major role in driving catastrophic floods. Emphasis should be put on understanding flood causes and impacts on vulnerable societies, controlling water-borne diseases, and recognizing the importance of compiling relevant and reliable flood information. Extreme rainfall in this dry region could be an asset for attenuating the regional water scarcity status if well harvested and managed. We hope this paper will induce the hydroclimate scholars to carry out more flood studies for the Sahel. It is only then encumbered meaningful opportunities for flood risk management can start to unveil.

Highlights

The climate of the Sahel Region, which expands from west to east Africa (Fig. 1), is renowned for variability and related phenomenal stressors (Epule et al, 2018)
Rainfall characteristics are changing in the Sahel at large from east to west. Rainfall data from both ground observations and satellites indicate an increase in the frequency of extreme events, the intensity of rain, and the inter-annual variability (Sulieman and Elagib, 2012; Ly et al, 2013; Zhang et al, 2017). These results reveal an increasing intensity and occurrence probability of extreme rainfall rather than a rainfall recovery, roughly since the beginning of the 21st century, with the intensification being stronger in the Eastern Sahel than the Western Sahel (Panthou et al, 2018)
During the period 1981–2019, the Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS) data show a highest rainfall recorded in one day across the Sahel region of 216.9 mm (Fig. 2a)

Summary

Introduction

The climate of the Sahel Region, which expands from west to east Africa (Fig. 1), is renowned for variability and related phenomenal stressors (Epule et al, 2018). While scientists from Africa are urging the United Nations to support preparations for imminent droughts in view of exacerbating climate change (Nature Editorial (NE), 2019; Padma, 2019), floods in the Sahel went far unacknowledged. Until 2018, research on the flood phenomena in the Sahel was 44% less than that of drought stressors (Epule et al, 2018). This attitude has, compounded the human and environmental vulnerability to floods. This attitude has, compounded the human and environmental vulnerability to floods. Tarhule (2005) stated that “historical flood records lack comprehensiveness, stan dardization, quality control, and scientific rigor.”

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