Identification of Potential Drought Areas in West Africa Under Climate Change and Variability

Abstract

The study investigates how the rising global temperature will affect the spatial pattern of rainfall and consequently drought in West Africa. The precipitation and potential evapotranspiration variables that are obtained from the Rossby Centre regional atmospheric model (RCA4) and driven by ten (10) global climate models under the RCP8.5 scenario were used. The model data were obtained from the Coordinated Regional Climate Downscaling Experiment (CORDEX) and analyzed at four specific global warming levels (GWLs) (i.e., 1.5 °C, 2.0 °C, 2.5 °C, and 3.0 °C) above the pre-industrial level. This study utilized four (4) indices: the standardized precipitation index, the precipitation concentration index, the precipitation concentration degree, and the precipitation concentration period over West Africa to explore the spatiotemporal variations in the characteristics of precipitation concentrations. Additionally, studying the impact of the four GWLs on consecutive dry days, consecutive wet days, and frequency of the intense rainfall events led to a better understanding of the spatiotemporal pattern of extreme precipitation. The results show that, at each GWL studied, the onset of rainfall comes 1 month earlier in the Gulf of Guinea compared to the historical period (1971-2000) with increasing rainfall intensity in the whole study domain, and the northeastern part of the study area becomes wetter. The rainfall concentration is uniformly distributed over the Gulf of Guinea and the Savanna zone for both the historical period and RCP8.5 scenario, while the Sahel zone which has shown an irregular concentration of rainfall for the historical period shows a uniform concentration of rainfall under all four GWLs.

Spatiotemporal Characteristics and Trend Analysis of Two Evapotranspiration-Based Drought Products and Their Mechanisms in Sub-Saharan Africa

“…However, an increase in P anomalies corresponded to increased interannual variability in NDVI values, which means that vegetation is usually restored to a normal status after a dry spell ends-one exception being the SAR, where, over the period from 1982 to 2012, NDVI variability showed a declining trend and P an increasing trend. The annual P cycle in this region is tied to the passage of the West African Monsoon (WAM), which accounts for nearly 80% of the region's annual P amount [63,64], thus exposing the region (SSG and HoA) to adverse future climate vulnerability [17][18][19]63,65]. The result of NDVI decline over the SAR is consistent with results reported in [66].…”

“…Although there is a lack of general consensus on global drought assessments [8][9][10][11][12], drought indices designed on the basis of the concept of atmospheric supply and demand have shaped our understanding of drought [3,7,[13][14][15]. Thus, within this context, the selfcalibrating Palmer Drought Severity Index (scPDSI), a typical example of such a drought index [12], has been widely used for drought climatology studies at global scales [8,9] and for regional specific studies [15][16][17][18][19], among others [6]. The scPDSI, by design, is a physical-based drought index that incorporates antecedent P, moisture supply, and demand (i.e., potential evaporation (PET)) to account for surface warming effects on wet and dry spells [12].…”

Impact of Large-Scale Climate Indices on Meteorological Drought of Coastal Ghana

“…Major historic drought periods observed are 1983 to 1984, 1988, 1993, 1997 to 1998, 2000 to 2001, 2009, and 2012-2013 for most coastal stations. e drought periods identified in the present study corroborate with some severe drought events identified in West Africa, Volta basin, and Sahel [37][38][39][40].…”

Spatial assessment of drought vulnerability using fuzzy-analytical hierarchical process: a case study at the Indian state of Odisha

“…Significant amount of the researches have been conducted regarding the drought prediction and susceptibility (Sheffield and Wood 2008;Gidey et al 2018;Spinoni et al 2018;Al Adaileh et al 2019;Ghosh 2019;Hoque et al 2020;Quenum et al 2019;Bhunia et al 2020). Drought mitigation and policy development studies for India have been done by various scientists (Bandyopadhyay et al 2020;Gupta et al 2020).…”