Geospatial analysis of meteorological drought impact on Southern Africa biomes

Abstract

Within Southern African biomes, droughts are recurrent with devastating impacts on ecological, economic, and human wellbeing. In this context, understanding the drought impact on vegetation is of extreme importance. However, information on drought impact on natural vegetation at the biome level is scanty and remains poorly understood. Most studies of drought impact on vegetation have largely focussed on crops. The few existing studies on natural vegetation are based on experiments and field measurements at individual tree level which are not representative of biomes. In this study, we mapped the spatial extent and severity of drought using the Standardized Precipitation Evapotranspiration Index (SPEI) and then quantified the drought impact on Southern African biomes using the Vegetation Condition Index (VCI) for the period 1998 to 2017. To compare drought impact across the biomes, we computed the percentage area of the biome with seasonal VCI <30. The drought trend for each biome was computed for each pixel using a linear regression model in R software using the seasonal VCI images from 1998 to 2017. Our result showed that extreme drought impact on vegetation was mainly confined to the southwestern biomes (i.e. the Nama karoo and desert biomes) with most drought occurring during the first half of the season. We also observed an increasing trend of VCI (1998 to 2017) across all biomes and this increasing VCI trend might be explained by woody encroachment which is prevalent in the Savannah and Grassland biomes. The results of this study provide baseline information on drought hotspots.

Uncertainty in Determination of Meteorological Drought Zones Based on Standardized Precipitation Index in the Territory of Poland

“…Due to high frequency and spatial extent, drought causes environmental and economic losses [ 55 , 56 , 57 ]. Analysis of the above-mentioned examples emphasizes the importance of monitoring, analysis, and assessment of the impact of drought on global, regional, and local scales.…”

The Drought Regime in Southern Africa: A Systematic Review

“…The document analysis revealed that the most important drought drivers in SA are (i) Ocean-Atmosphere interactions, with 50% of the total number of studies included, comprising El Niño Southern Oscillation (ENSO), other Ocean-Atmosphere interaction events, namely between the Indian and/or Atlantic Ocean and the Atmosphere, SST anomalies, (ii) anthropic influence, including fires, gas emissions, and global warming (13%), (iii) heat waves (4%) and (vi) lack of preparation and follow-up (2%), which are important factors of the magnitude of the drought impacts. The results of the literature review about the drought factors (Table 4) point to ENSO as the main driver of the most severe drought events and source of climate variability and predictability in the SA region [45,49]. ENSO plays a crucial role in defining drought in SA, associated with more than 66% of the severe droughts that occurred in the region, e.g., [45][46][47][53][54][55][56][57].…”

“…The literature review identified seven major types of drought impacts in SA: (i) Scarcity of potable water, food insecurity, and hunger [29,33,43,44,46,49,51,52,60,62,63,67,79,[128][129][130], (ii) increases in malnutrition, morbidity, and mortality [29,50,52,60,72,76,130], (iii) loss of agricultural production [33,44,[50][51][52]76,84], (iv) reduction of industrial and hydroelectric energy production [33,62], (v) pressure on the economy and promotion of emigration [33,60,79,84], (vi) regional humanitarian crisis [129], (vii) risk of groundwater drought [83], and (viii) degradation of ecosystems [60,63,68,129,131]. Drought is indeed one of the natural hazards that affect various sectors in SA, where many socioeconomic activities depend on rainfed agriculture [65,…”

Spatiotemporal changes in droughts in Iraq for shared socioeconomic pathways

“…Drought causes water shortage and affects the economic activities and population over a large area (Kala 2017;Malik et al 2021;Marumbwa et al 2021;Salehie et al 2022a). Therefore, the economic impact of droughts is considered the worst compared to other hydrological hazards (Damania et al 2017;Sharafati et al 2020).…”