Search

Renewable energy is recognized in Africa as a means for climate change mitigation, but also to provide access to electricity in sub‐Saharan Africa, where three‐quarters of the global population without electricity resides. Reliable and highly resolved renewable energy potential (REP) information is indispensable to support power plants expansion. Existing atmospheric data sets over Africa that are used for REP estimates are often characterized by data gaps, or coarse resolution. With the aim to overcome these challenges, the ICOsahedral Nonhydrostatic (ICON) Numerical Weather Prediction (ICON‐NWP) model in its Limited Area Mode (ICON‐LAM) is implemented and run over southern Africa in a hindcast dynamical downscaling setup at a convection‐permitting 3.3 km horizontal resolution. The simulation time span covers contrasting solar and wind weather years from 2017 to 2019. To assess the suitability of the novel simulations for REP estimates, the simulated hourly 10 m wind speed (sfcWind) and hourly surface solar irradiance (rsds) are extensively evaluated against a large compilation of in situ observations, satellite, and composite data products. ICON‐LAM reproduces the spatial patterns, temporal evolution, the variability, and absolute values of sfcWind sufficiently well, albeit with a slight overestimation and a mean bias (mean error (ME)) of 1.12 m s−1 over land. Likewise the simulated rsds with an ME of 50 W m−2 well resembles the observations. This new ICON simulation data product will be the basis for ensuing REP estimates that will be compared with existing lower resolution data sets. Plain Language Summary: There are still approximately 580 million people in Africa without reliable electricity supply. Renewable energy is broadly accepted as an important solution for Africa to fill the power supply gap and to mitigate climate change. Renewable energy potential (REP) information is thereby imperative for the expansion of renewable energy power planning. With conventional REP estimates, challenges are often linked to the meteorological input data, due to either the relatively coarse spatial resolution, data gaps in space and time, or data quality in general. In this study, we implemented and ran the atmospheric model ICOsahedral Nonhydrostatic (ICON) from the German Weather Service and partners at 3 km high‐resolution. The renewable energy variables wind speed and solar irradiance from these simulations are evaluated against an extensive in situ observations data set, as well as satellite, and other composite data products. In a comparison with more than 200 stations from three different in situ observation networks, it can be shown that ICON can reproduce REP‐related variables with a level of sophistication that the data is likely to offer added value over conventional inputs to REP assessments. The study is an example on how numerical models can fill in gaps in data‐scarce regions to produce useable information. Key Points: A new convection‐permitting regional ICOsahedral Nonhydrostatic (ICON) model setup over southern Africa is presented and evaluatedThe spatially and temporally highly resolved ICON wind and solar fields are inputs for improved renewable energy potential estimatesICON outputs agree well with hourly in situ observations and satellite data; wind speeds are slightly overestimated [ABSTRACT FROM AUTHOR]

Land surface modelling runs with CLM5 over Africa at 3 km resolution were carried out and we assessed the impact of different sources of soil information and different upscaling strategies of the soil information, also in combination with different atmospheric forcings and different temporal resolutions of those atmospheric forcings. FAO and SoilGrids250m were used as soil information. SoilGrids information at 250 m resolution was upscaled to the 3 km grid scale by three different methods: (i) random selection of one of the small SoilGrids250m grid cells contained in the model grid cell; (ii) arithmetic averaging of SoilGrids soil texture values and (iii) selection of the dominant soil texture. These different soil model inputs were combined with different atmospheric forcings model inputs, which provide inputs at different temporal resolutions: CRUNCEPv7 (6-hourly input resolution), GSWPv3 (3-hourly) and WFDE5 (hourly). We found that varying the source of soil texture information (FAO or SoilGrids250m) influences model water balance outputs more than the upscaling methodology of the soil texture maps. However, for high temporal resolution of atmospheric forcings (WFDE5) the different soil texture upscaling methods result in large differences in simulated evapotranspiration, surface runoff and subsurface runoff at the local and regional scales related to the higher resolution representation of rainfall intensity in the model. The upscaling methodology of fine scale soil texture information influences land surface model simulation results, but only clearly in combination with high temporal resolution atmospheric forcings. [ABSTRACT FROM AUTHOR]

• Five decades of land surface hydrology in Africa simulated. • Five decades of groundwater recharge analyzed. • Long-term annual groundwater sustainable yield quantified. • Groundwater in Africa recharged at 57.8 mm yr−1 on average, equivalent to 1793.6 km3 yr−1. • Africa's potential optimum sustainable yield is 20.6 mm yr−1, corresponding to 643.1 km3 yr−1. Groundwater stands as a vital water resource for both present and future generations in Africa. This underscores the importance of examining the sustainability of current groundwater consumption across the continent, along with its capacity to fulfill the current human and essential environmental water needs. Groundwater sustainable yield is a suitable indicator for assessing groundwater sustainability but has not yet been quantified properly across Africa. A thorough quantification of groundwater sustainable yield necessitates a profound comprehension of the spatio-temporal fluctuations in surface hydrology, groundwater recharge, environmental flow, and sectoral water use. In this study, high spatial resolution (10 km) land surface hydrology was simulated for five decades (1965–2014) across Africa by the Community Land Model version 5 at half-hourly time step and aggregated to monthly and annual temporal resolutions. Then, groundwater recharge and environmental flow were quantified based on the water balance approach for the whole continent. Finally, by including African sectoral water use data available for four decades (1971–2010) we obtained the long-term average of groundwater sustainable yield. Based on extensive simulations of long-term land surface hydrology, we discovered that the groundwater system in Africa experienced an average annual recharge of 57.8 mm yr−1 (with a standard deviation of 110.8 mm yr−1 serving as an indicator of spatial variability), corresponding roughly to an annual recharge volume of 1793.6 km3 yr−1. Furthermore, our analysis revealed that the entire continent possesses an annual average potential sustainable yield (with standard deviations) of 4.5 mm yr−1 (10.2), 20.6 mm yr−1 (42.9), and 37.3 mm yr−1 (75.7) under conservative, optimum, and suitable water consumption scenarios, respectively. This calculated annual groundwater sustainable yield corresponds to 141.9 km3 yr−1, 643.1 km3 yr−1, and 1160.5 km3 yr−1 for the conservative, optimum, and suitable scenarios, respectively. Furthermore, the calculated sustainable yield volume is contrasted with the total water storage figures documented for 50 countries throughout Africa. The outcomes illustrate that our calculated annual sustainable yield equates to roughly 0.02%, 0.1%, and 0.17% of the reported groundwater storage across the entire continent. Based on the estimated long-term average sustainable yield and the reported total water storage at the national level, our conclusion is that the accessible groundwater resources could potentially satisfy the current water requirements of both humans and the environment in African countries. This study offers the first model-based estimation of groundwater availability across Africa, potentially serving as a catalyst to inspire further progress toward adopting more sustainable approaches to groundwater usage on the continent. [ABSTRACT FROM AUTHOR]