Spatial Relationship between Precipitation and Runoff in Africa

Abstract

Abstract. Lack of sufficient and reliable hydrological information is a key hindrance to water resource planning and management in Africa. Hence, the objective of this research is to examine the relationship between precipitation and runoff at three spatial scales, including the whole continent, 25 major basins and 55 countries. For this purpose, the long-term monthly runoff coefficient (Rc) was estimated using the long-term monthly runoff data (R) calculated from the Global Runoff Data Centre (GRDC) streamflow records and Global Precipitation Climatology Centre (GPCC) precipitation datasets for the period of time spanning from 1901 to 2017. Subsequently, the observed Rc data were interpolated in order to estimate Rc over the ungauged basins under guidance of key runoff controlling factors, including the land-surface temperature (T), precipitation (P) and potential runoff coefficient (Co) inferred from the land use and land cover, slope and soil texture information. The results show that 16 % of the annual mean precipitation (672.52 mm) becomes runoff (105.72 mm), with a runoff coefficient of 0.16, and the remaining 84 % (566.80 mm) evapotranspirates over the continent during 1901–2017. Spatial analysis reveals that the precipitation–runoff relationship varies significantly among different basins and countries, mainly dependent on climatic conditions and its inter-annual variability. Generally, high runoff depths and runoff coefficients are observed over humid tropical basins and countries with high precipitation intensity compared to those located in subtropical and temperate drylands.

Spatial distribution of specific runoff in Serbia based on rainfall-runoff relationship

“…Mean runoff coefficients are most strongly correlated to the indicators representing climate such as mean annual precipitation and the long-term ratio of actual evaporation to precipitation through affecting long-term soil moisture. This can be seen on global (McMahon, Peel, Pegram, & Smith, 2011), continental (Karamage et al, 2018), and country scales (Merz & Blöschl, 2009;Ri, Jiang, Sivakumar, & Pang, 2019). Land use, soil types, and geology do not seem to exert a major control on runoff coefficients on these spatial scales.…”

Water Resources in Africa: The Role of Earth Observation Data and Hydrodynamic Modeling to Derive River Discharge

“…are now routinely derived from space and efficiently complement the lack of the traditional in situ data. As the main driver of hydrological extremes (Karamage et al 2018), precipitation plays an important role in these new EO datasets. Satgé et al (2020) provided an in depth analysis of 23 precipitation datasets, highlighting the importance of the very few rainfall gauges to improve RS precipitation products.…”

Review article: Potential of Nature-Based Solutions to Mitigate Hydro-Meteorological Risks in Sub-Saharan Africa

“…This is appreciated in the more recent definition of NBS by the 5th Session of the United Nations Environment Assembly as "actions to protect, conserve, restore, sustainably use and manage natural or modified terrestrial, freshwater, coastal and marine ecosystems, which address social, economic and environmental challenges effectively and adaptively, while simultaneously providing human wellbeing, ecosystem services and resilience and biodiversity benefits" (Seddon, 2022). As of 2018, SSA was only 0.16% built-up (Karamage et al, 2018) compared to 4.2% in Europe (EUROSTAT, 2021); thus, it is plausible that greater attention will be on ecosystem conservation in SSA. Even though there are many definitions of NBS, its principles provide a common understanding and framework for its implementation.…”