Management of Ground Water in Africa Including Transboundary Aquifers: Implications for Food Security, Livelihood and Climate Change Adaptation

Groundwater is one of the most important sources for drinking water, livestock water, and irrigation in Africa. It is of vital importance in meeting the Millennium Development Goals (MDGs) target of accessing clean water, as most of rural Africa and a considerable part of urban Africa are supplied by groundwater. Groundwater also has a major role to play in improving food security through expansion of irrigation supplied by shallow and deep wells. As such, groundwater has high relevance to the development and wellbeing of Africa, if adequately assessed and sustainably exploited. However, impacts of rapid development and climate change on water resources, including groundwater, are expected to be very severe unless major actions are taken to address the limited human and institutional capacity and hydrogeological knowledge base needed to devise sustainable adaptive water management strategies. Whilst the potential for groundwater resources development and the extent of their vulnerability due to climate change in the African context continue to be reported in the literature, a quantitative understanding of these issues remains poor. Although groundwater systems respond to human and climatic changes slowly (relative to surface water systems), climate change still could affect groundwater significantly through changes in groundwater recharge as well as groundwater storage and utilization. These changes result from changes in temperature and precipitation or from change in land use/land cover, and increased demand. There is therefore a need for ensuring sustainability and proper management of groundwater resources through instituting proper aquifer management practices such as the establishment of groundwater monitoring systems, better understanding of the role of groundwater storage and groundwater discharges in sustaining aquatic ecosystems, understanding the interactions between various aquifers (including transboundary aquifers) and assessing the impact of increased pumping from various aquifer systems on the sustainability of groundwater abstraction. This paper provides an overview of the regional hydrogeological framework, the current state of knowledge of aquifer systems, their development potential and climate change impacts on groundwater, research gaps, and policy implications for meeting the MDGs of accessing clean water and livelihood goals in Africa

Resilience in the Limpopo Basin : The potential role of the transboundary Ramotswa aquifer - Baseline report

The overall objective of the RAMOTSWA project is to support a long-term joined vision and cooperation on the shared groundwater resources of the Upper Limpopo region, where the states share significant and valuable underground freshwater resources as well as space for enhanced subsurface water storage. The project will facilitate and promote joint management and better groundwater governance focused on coordination, scientific knowledge, social redress and environmental sustainability, in order to reduce poverty and inequity, increase prosperity, and improve livelihoods and water and food security in the face of climate change and variability

Resilience in the Limpopo Basin : The potential role of the transboundary Raotswa aquifer - Final draft

As complementary report of the baseline report, this report focus on the hydrogeological assessment of the Ramotswa Transboundary Aquifer and covers only aspects related to the biophysical conditions of the aquifer which is a karstic dolomit aquife straddling the international border between Botswana and South Africa. The assessment is based on existing data and field data collected (including Airborne Electro-Magnetic survey) during the period September 2015 –November 2016. The technical knowledge developed in the report will be used as based for developing tools for harmonized management and fostering crossborder dialogue in order to help building the joint Strategic Action Programme which will provide, not exclusively, guidelines for better monitoring and future assessment of the aquifer

Geochemical Distribution of Trace Elements in Groundwater from the North Mara Large-Scale Gold Mining Area of Tanzania

Research Article published by Ground Water Monitoring and RemediationThe infl uence of large-scale mining operations on groundwater quality was investigated in this study. Trace element concentrations in groundwater samples from the North Mara mining area of northern Tanzania were analyzed. Statistical analyses for relationships between elemental concentrations in the samples and distance of a sampling site from the mine tailings dam were also conducted. Eleven trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were determined, and averages of Fe and Al concentrations were higher than levels accepted by the Tanzanian drinking water guideline. Levels of Pb in three samples were higher than the World Health Organization ( WHO ) and United States Environmental Protection Agency ( USEPA ) drinking water guidelines of 10 and 15 µg/L, respectively. One sample contained a higher As level than the WHO and USEPA guideline of 10 µg/L. The correlation between element concentrations and distance from the mine tailings dam was examined using the hierarchical agglomeration cluster analysis method. A signifi cant difference in the elemental concentration existed depending on the distance from the mine tailings dam. Mann–Whitney U -test post hoc analysis confi rmed a relationship between element concentration and distance of a sampling site from the mine tailings dam. This relationship raises concerns about the increased risks of trace elements to people and ecosystem health. A metal pollution index also suggested a relationship between elemental concentrations in the groundwater and the sampling sites’ proximity from the mine tailings dam

Observed controls on resilience of groundwater to climate variability in sub-Saharan Africa

Groundwater in sub-Saharan Africa supports livelihoods and poverty alleviation1,2, maintains vital ecosystems, and strongly influences terrestrial water and energy budgets. Yet the hydrological processes that govern groundwater recharge and sustainability—and their sensitivity to climatic variability—are poorly constrained4. Given the absence of firm observational constraints, it remains to be seen whether model-based projections of decreased water resources in dry parts of the region4 are justified. Here we show, through analysis of multidecadal groundwater hydrographs across sub-Saharan Africa, that levels of aridity dictate the predominant recharge processes, whereas local hydrogeology influences the type and sensitivity of precipitation–recharge relationships. Recharge in some humid locations varies by as little as five per cent (by coefficient of variation) across a wide range of annual precipitation values. Other regions, by contrast, show roughly linear precipitation–recharge relationships, with precipitation thresholds (of roughly ten millimetres or less per day) governing the initiation of recharge. These thresholds tend to rise as aridity increases, and recharge in drylands is more episodic and increasingly dominated by focused recharge through losses from ephemeral overland flows. Extreme annual recharge is commonly associated with intense rainfall and flooding events, themselves often driven by large-scale climate controls. Intense precipitation, even during years of lower overall precipitation, produces some of the largest years of recharge in some dry subtropical locations. Our results therefore challenge the ‘high certainty’ consensus regarding decreasing water resources in such regions of sub-Saharan Africa. The potential resilience of groundwater to climate variability in many areas that is revealed by these precipitation–recharge relationships is essential for informing reliable predictions of climate-change impacts and adaptation strategies

Cartographie du potentiel de développement de l'irrigation durable avec des eaux souterraines renouvelables en Afrique pour réduire l'insécurité alimentaire africaine

In Africa, groundwater irrigation is considered a reliable and affordable means to increase food security. Areas equipped for groundwater irrigation in Africa have however, developed slowly since 1950 and remain very limited. To date, no studies have identified the sustainable development potential of irrigation with renewable groundwater across Africa. This study is based on two approaches to locate and quantify this potential. The quantitative hydrological approach is based on the estimation of the current crop irrigation need and available renewable groundwater for irrigation after all other water needs, including environmental, have been satisfied. This approach shows that the potential is 44.6 x 106 ha or 20.5% of the cropland over the continent. The environmental approach redefines the quantitative potential by considering a set of biophysical and socio-economic factors conducive to sustainable development of groundwater irrigation. The potential is then 19.3 x 106 ha and it is reduced mainly from the equatorial regions where the need for irrigation is limited. In fact, without considering the countries of the Maghreb and South Africa where current irrigation by groundwater exceeds the estimated potential, groundwater irrigated areas could be multiplied by 75. The largest areas which are worthwhile to develop are mainly located along a west-east line from Angola to the north of Mozambique and a line south of the Sahel. The dry regions of the Sahel, East Africa and Southern Africa have limited development potential which is more suitable to small-scale agriculture and could greatly improve food security in Africa.En Afrique, l'irrigation des cultures par les eaux souterraines est considérée comme un outil fiable et abordable pour augmenter la sécurité alimentaire mais les superficies équipées pour l'irrigation par les eaux souterraines restent très limitées. Cette étude se base sur deux approches pour localiser et quantifier le potentiel de développement de l’irrigation des cultures par les eaux souterraines renouvelables sur l'ensemble du continent. L’approche quantitative et hydrologique s’appuie sur l’estimation des eaux souterraines renouvelables disponibles après satisfaction de tous les autres besoins, y compris environnementaux et sur le besoin en irrigation des cultures et montre un potentiel s’élevant à 44.6 x 106 ha soit 20.5% des cultures du continent. L’approche contextuelle redéfinit le potentiel quantitatif en considérant un ensemble de facteurs biophysiques et socio-économiques propices au développement de l’irrigation par les eaux souterraines. Le potentiel s’élève alors à 19,3 x 106 ha et est réduit essentiellement dans les régions équatoriales où le besoin en irrigation est limité. En fait, sans considérer les pays où l’irrigation actuelle par les eaux souterraines excède le potentiel estimé, les surfaces irriguées pourraient être multipliées par 75. Les plus grandes surfaces propices au développement de l'irrigation sont principalement situées le long d’une ligne ouest-est de de l’Angola au nord du Mozambique et d’une ligne au sud du Sahel. Les régions sèches du Sahel et de l’Afrique de l’Est et australe ont un potentiel de développement plus limité, plus adapté à la petite agriculture, qui pourrait améliorer amplement la sécurité alimentaire en Afrique

Cartographie du potentiel de développement de l'irrigation durable avec des eaux souterraines renouvelables en Afrique pour réduire l'insécurité alimentaire africaine

In Africa, groundwater irrigation is considered a reliable and affordable means to increase food security. Areas equipped for groundwater irrigation in Africa have however, developed slowly since 1950 and remain very limited. To date, no studies have identified the sustainable development potential of irrigation with renewable groundwater across Africa. This study is based on two approaches to locate and quantify this potential. The quantitative hydrological approach is based on the estimation of the current crop irrigation need and available renewable groundwater for irrigation after all other water needs, including environmental, have been satisfied. This approach shows that the potential is 44.6 x 106 ha or 20.5% of the cropland over the continent. The environmental approach redefines the quantitative potential by considering a set of biophysical and socio-economic factors conducive to sustainable development of groundwater irrigation. The potential is then 19.3 x 106 ha and it is reduced mainly from the equatorial regions where the need for irrigation is limited. In fact, without considering the countries of the Maghreb and South Africa where current irrigation by groundwater exceeds the estimated potential, groundwater irrigated areas could be multiplied by 75. The largest areas which are worthwhile to develop are mainly located along a west-east line from Angola to the north of Mozambique and a line south of the Sahel. The dry regions of the Sahel, East Africa and Southern Africa have limited development potential which is more suitable to small-scale agriculture and could greatly improve food security in Africa.En Afrique, l'irrigation des cultures par les eaux souterraines est considérée comme un outil fiable et abordable pour augmenter la sécurité alimentaire mais les superficies équipées pour l'irrigation par les eaux souterraines restent très limitées. Cette étude se base sur deux approches pour localiser et quantifier le potentiel de développement de l’irrigation des cultures par les eaux souterraines renouvelables sur l'ensemble du continent. L’approche quantitative et hydrologique s’appuie sur l’estimation des eaux souterraines renouvelables disponibles après satisfaction de tous les autres besoins, y compris environnementaux et sur le besoin en irrigation des cultures et montre un potentiel s’élevant à 44.6 x 106 ha soit 20.5% des cultures du continent. L’approche contextuelle redéfinit le potentiel quantitatif en considérant un ensemble de facteurs biophysiques et socio-économiques propices au développement de l’irrigation par les eaux souterraines. Le potentiel s’élève alors à 19,3 x 106 ha et est réduit essentiellement dans les régions équatoriales où le besoin en irrigation est limité. En fait, sans considérer les pays où l’irrigation actuelle par les eaux souterraines excède le potentiel estimé, les surfaces irriguées pourraient être multipliées par 75. Les plus grandes surfaces propices au développement de l'irrigation sont principalement situées le long d’une ligne ouest-est de de l’Angola au nord du Mozambique et d’une ligne au sud du Sahel. Les régions sèches du Sahel et de l’Afrique de l’Est et australe ont un potentiel de développement plus limité, plus adapté à la petite agriculture, qui pourrait améliorer amplement la sécurité alimentaire en Afrique

Cartographie du potentiel de développement de l'irrigation durable avec des eaux souterraines renouvelables en Afrique pour réduire l'insécurité alimentaire africaine

In Africa, groundwater irrigation is considered a reliable and affordable means to increase food security. Areas equipped for groundwater irrigation in Africa have however, developed slowly since 1950 and remain very limited. To date, no studies have identified the sustainable development potential of irrigation with renewable groundwater across Africa. This study is based on two approaches to locate and quantify this potential. The quantitative hydrological approach is based on the estimation of the current crop irrigation need and available renewable groundwater for irrigation after all other water needs, including environmental, have been satisfied. This approach shows that the potential is 44.6 x 106 ha or 20.5% of the cropland over the continent. The environmental approach redefines the quantitative potential by considering a set of biophysical and socio-economic factors conducive to sustainable development of groundwater irrigation. The potential is then 19.3 x 106 ha and it is reduced mainly from the equatorial regions where the need for irrigation is limited. In fact, without considering the countries of the Maghreb and South Africa where current irrigation by groundwater exceeds the estimated potential, groundwater irrigated areas could be multiplied by 75. The largest areas which are worthwhile to develop are mainly located along a west-east line from Angola to the north of Mozambique and a line south of the Sahel. The dry regions of the Sahel, East Africa and Southern Africa have limited development potential which is more suitable to small-scale agriculture and could greatly improve food security in Africa.En Afrique, l'irrigation des cultures par les eaux souterraines est considérée comme un outil fiable et abordable pour augmenter la sécurité alimentaire mais les superficies équipées pour l'irrigation par les eaux souterraines restent très limitées. Cette étude se base sur deux approches pour localiser et quantifier le potentiel de développement de l’irrigation des cultures par les eaux souterraines renouvelables sur l'ensemble du continent. L’approche quantitative et hydrologique s’appuie sur l’estimation des eaux souterraines renouvelables disponibles après satisfaction de tous les autres besoins, y compris environnementaux et sur le besoin en irrigation des cultures et montre un potentiel s’élevant à 44.6 x 106 ha soit 20.5% des cultures du continent. L’approche contextuelle redéfinit le potentiel quantitatif en considérant un ensemble de facteurs biophysiques et socio-économiques propices au développement de l’irrigation par les eaux souterraines. Le potentiel s’élève alors à 19,3 x 106 ha et est réduit essentiellement dans les régions équatoriales où le besoin en irrigation est limité. En fait, sans considérer les pays où l’irrigation actuelle par les eaux souterraines excède le potentiel estimé, les surfaces irriguées pourraient être multipliées par 75. Les plus grandes surfaces propices au développement de l'irrigation sont principalement situées le long d’une ligne ouest-est de de l’Angola au nord du Mozambique et d’une ligne au sud du Sahel. Les régions sèches du Sahel et de l’Afrique de l’Est et australe ont un potentiel de développement plus limité, plus adapté à la petite agriculture, qui pourrait améliorer amplement la sécurité alimentaire en Afrique

Availability and use of water resources

Peer Revie