Your search found 10 records
1 Calow, R. C.; Robins, N. S.; MacDonald, A. M.; MacDonald, D. M. J.; Gibbs, B. R.; Orpen, W. R. G.; Mtembezeka, P.; Andrews, A. J.; Appiah, S. O. 1997. Groundwater management in drought-prone areas of Africa. International Journal of Water Resources Development, 13(2):241-261.
(Location: IWMI-HQ Call no: PER Record No: H020729)
2 MacDonald, A. M.; Davies, J. 2000. A brief review of groundwater for rural water supply in sub-Saharan Africa. Keyworth, Nottingham, UK: British Geological Survey. 24p. (BGS Technical Report WC/00/33 / Overseas Geology Series)
Water supply ; Rural development ; Groundwater ; Sedimentary materials ; Aquifers ; Hydrology ; Wells / Africa South of Sahara
(Location: IWMI HQ Call no: e-copy only Record No: H042022)
http://siteresources.worldbank.org/INTWRD/864188-1171045933145/21215329/31BGSAfricaRuralGW.pdf
https://vlibrary.iwmi.org/PDF/H042022.pdf
https://vlibrary.iwmi.org/PDF/H042022.pdf
(2.25 MB)
3 MacDonald, A. M.; Calow, R.; Nicol, A. L.; Hope, B.; Robins, N. S. 2001. Ethiopia: water security and drought. Keyworth, Nottingham, UK: British Geological Survey. 1p. (British Geological Survey Technical Report WC/01/02)
(Location: IWMI HQ Call no: e-copy only Record No: H042023)
http://www-esd.worldbank.org/esd/ard/groundwater/pdfreports/Struggle_for_Water_App6_Pt2.pdf
https://vlibrary.iwmi.org/PDF/H042023.pdf
https://vlibrary.iwmi.org/PDF/H042023.pdf
(2.04 MB)
4 MacDonald, A. M.; Taylor, R. G.; Bonsor, H. C. 2012. Groundwater in Africa: is there sufficient water to support the intensification of agriculture from 'land grabs'? In Allan, T.; Keulertz, M.; Sojamo, S.; Warner, J. (Eds.). Handbook of land and water grabs in Africa: foreign direct investment and food and water security. London, UK: Routledge. pp.376-383.
Land acquisitions ; Groundwater development ; Water storage ; Groundwater irrigation ; Water availability ; Crop production ; Intensification / Africa
(Location: IWMI HQ Call no: 333.91 G000 ALL Record No: H045689)
5 Kolusu, S. R.; Shamsudduha, M.; Todd, M. C.; Taylor, R. G.; Seddon, D.; Kashaigili, J. J.; Ebrahim, Girma Y.; Cuthbert, M. O.; Sorensen, J. P. R.; Villholth, Karen G.; MacDonald, A. M.; MacLeod, D. A. 2019. The El Nino event of 2015-2016: climate anomalies and their impact on groundwater resources in East and Southern Africa. Hydrology and Earth System Sciences, 23: 1751-1762. [doi: https://doi.org/10.5194/hess-23-1751-2019]
El Nino ; Groundwater management ; Water resources ; Water storage ; Climate change ; Rainfall ; Drought ; Water balance ; Water levels ; Surface water ; Precipitation ; Evapotranspiration ; Satellite imagery ; Satellite observation / East Africa / SouthernAfrica / Limpopo Basin
(Location: IWMI HQ Call no: e-copy only Record No: H049164)
https://www.hydrol-earth-syst-sci.net/23/1751/2019/hess-23-1751-2019.pdf
https://vlibrary.iwmi.org/pdf/H049164.pdf
https://vlibrary.iwmi.org/pdf/H049164.pdf
(2.80 MB)
The impact of climate variability on groundwater storage has received limited attention despite widespread dependence on groundwater as a resource for drinking water, agriculture and industry. Here, we assess the climate anomalies that occurred over Southern Africa (SA) and East Africa, south of the Equator (EASE), during the major El Niño event of 2015–2016, and their associated impacts on groundwater storage, across scales, through analysis of in situ groundwater piezometry and Gravity Recovery and Climate Experiment (GRACE) satellite data. At the continental scale, the El Niño of 2015–2016 was associated with a pronounced dipole of opposing rainfall anomalies over EASE and Southern Africa, north–south of ~12° S, a characteristic pattern of the El Niño–Southern Oscillation (ENSO). Over Southern Africa the most intense drought event in the historical record occurred, based on an analysis of the cross-scale areal intensity of surface water balance anomalies (as represented by the standardised precipitation evapotranspiration index – SPEI), with an estimated return period of at least 200 years and a best estimate of 260 years. Climate risks are changing, and we estimate that anthropogenic warming only (ignoring changes to other climate variables, e.g. precipitation) has approximately doubled the risk of such an extreme SPEI drought event. These surface water balance deficits suppressed groundwater recharge, leading to a substantial groundwater storage decline indicated by both GRACE satellite and piezometric data in the Limpopo basin. Conversely, over EASE during the 2015–2016 El Niño event, anomalously wet conditions were observed with an estimated return period of ~10 years, likely moderated by the absence of a strongly positive Indian Ocean zonal mode phase. The strong but not extreme rainy season increased groundwater storage, as shown by satellite GRACE data and rising groundwater levels observed at a site in central Tanzania. We note substantial uncertainties in separating groundwater from total water storage in GRACE data and show that consistency between GRACE and piezometric estimates of groundwater storage is apparent when spatial averaging scales are comparable. These results have implications for sustainable and climate-resilient groundwater resource management, including the potential for adaptive strategies, such as managed aquifer recharge during episodic recharge events.
6 Cuthbert, M. O.; Taylor, R. G.; Favreau, G.; Todd, M. C.; Shamsudduha, M.; Villholth, Karen G.; MacDonald, A. M.; Scanlon, B. R.; Kotchoni, D. O. V.; Vouillamoz, J.-M.; Lawson, F. M. A.; Adjomayi, P. A.; Kashaigili, J.; Seddon, D.; Sorensen, J. P. R.; Ebrahim, Girma Yimer; Owor, M.; Nyenje, P. M.; Nazoumou, Y.; Goni, I.; Ousmane, B. I.; Sibanda, T.; Ascott, M. J.; Macdonald, D. M. J.; Agyekum, W.; Koussoube, Y.; Wanke, H.; Kim, H.; Wada, Y.; Lo, M.-H.; Oki, T.; Kukuric, N. 2019. Observed controls on resilience of groundwater to climate variability in sub-Saharan Africa. Nature, 572(7768):230-234. [doi: https://doi.org/10.1038/s41586-019-1441-7]
Groundwater recharge ; Climate change ; Resilience ; Groundwater table ; Observation ; Precipitation ; Hydrology ; Hydrography ; Models ; Arid zones ; Rain / Africa South of Sahara / Benin / Uganda / United Republic of Tanzania / Zimbabwe / South Africa / Namibia / Niger / Ghana / Burkina Faso
(Location: IWMI HQ Call no: e-copy only Record No: H049316)
https://www.nature.com/articles/s41586-019-1441-7.epdf?author_access_token=UgizrPwmrGzlbL33bjbvQdRgN0jAjWel9jnR3ZoTv0M3C122Ih9FQbr0PbeOlDAX9EZlbSwXsaUcJ-Vq-8EelgPfWJQTdVE-2_3g7yypNR4C-qTOMe7Ux1weufjBdaT9SyaKgJjfKYgJ2fqsjIRLng%3D%3D
https://vlibrary.iwmi.org/pdf/H049316.pdf
https://vlibrary.iwmi.org/pdf/H049316.pdf
(7.21 MB)
Groundwater in sub-Saharan Africa supports livelihoods and poverty alleviation1,2 , maintains vital ecosystems, and strongly influences terrestrial water and energy budgets3 . Yet the hydrological processes that govern groundwater recharge and sustainability—and their sensitivity to climatic variability—are poorly constrained4,5 . 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 resources4 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.
7 Chan, W. C. H.; Thompson, J. R.; Taylor, R. G.; Nay, A. E.; Ayenew, T.; MacDonald, A. M.; Todd, M. C. 2020. Uncertainty assessment in river flow projections for Ethiopia’s Upper Awash Basin using multiple GCMs [General Circulation Models] and hydrological models. Hydrological Sciences Journal, 65(10):1720-1737. [doi: https://doi.org/10.1080/02626667.2020.1767782]
River basins ; Flow discharge ; Forecasting ; Hydrology ; Models ; Calibration ; Climate change ; Precipitation ; Evapotranspiration ; Assessment ; Uncertainty / Ethiopia / Upper Awash Basin
(Location: IWMI HQ Call no: e-copy only Record No: H049953)
(4.45 MB)
Uncertainty in climate change impacts on river discharge in the Upper Awash Basin, Ethiopia, is assessed using five MIKE SHE hydrological models, six CMIP5 general circulation models (GCMs) and two representative concentration pathways (RCP) scenarios for the period 2071–2100. Hydrological models vary in their spatial distribution and process representations of unsaturated and saturated zones. Very good performance is achieved for 1975–1999 (NSE: 0.65–0.8; r: 0.79–0.93). GCM-related uncertainty dominates variability in projections of high and mean discharges (mean: –34% to +55% for RCP4.5, – 2% to +195% for RCP8.5). Although GCMs dominate uncertainty in projected low flows, inter-hydrological model uncertainty is considerable (RCP4.5: –60% to +228%, RCP8.5: –86% to +337%). Analysis of variance uncertainty attribution reveals that GCM-related uncertainty occupies, on average, 68% of total uncertainty for median and high flows and hydrological models no more than 1%. For low flows, hydrological model uncertainty occupies, on average, 18% of total uncertainty; GCM-related uncertainty remains substantial (average: 28%).
8 Lapworth, D. J.; Dochartaigh, B. O.; Nair, T.; O'Keeffe, J.; Krishan, G.; MacDonald, A. M.; Khan, M.; Kelkar, N.; Choudhary, S.; Krishnaswamy, J.; Jackson, C. R. 2021. Characterising groundwater-surface water connectivity in the Lower Gandak Catchment, a barrage regulated biodiversity hotspot in the mid-Gangetic Basin. Journal of Hydrology, 594:125923. (Online first) [doi: https://doi.org/10.1016/j.jhydrol.2020.125923]
Groundwater recharge ; Groundwater table ; Water levels ; Surface water ; Catchment areas ; River basins ; Biodiversity ; Ecology ; Salinity ; Irrigation canals ; Discharges ; Water extraction ; Monitoring ; Drinking water ; Alluvial aquifers ; Rain ; Isotope analysis / India / Indo-Gangetic Basin / River Gandak
(Location: IWMI HQ Call no: e-copy only Record No: H050154)
(13.00 MB)
The alluvial aquifer system of the Indo-Gangetic Basin (IGB) is one of the world’s most important freshwater resources, sustaining humans and river ecosystems. Understanding groundwater recharge processes and connections to meteoric and surface water is necessary for effective water resource management for human and wider ecological requirements. Parts of the mid-Gangetic Basin, across eastern Uttar Pradesh and Bihar, are characterised by stable long-term groundwater levels, high annual rainfall, and limited historical groundwater use compared to parts of Northwest India for example. In this paper we use a combination of environmental tracers and hydrograph observations to characterise sources of recharge and groundwater-surface water interaction using a transect approach across the catchment of the River Gandak, a major barrage-regulated tributary of the River Ganga. Stable isotope results show that the dominant source of groundwater recharge, in the shallow (0–40 m bgl) Holocene and underlying Pleistocene aquifer system (>40 m bgl), is local rainfall. The shallow Holocene aquifer is also supplemented by local recharge from river and canal seepage and irrigation return flow in the upper and mid parts of the catchment. These observations are corroborated by evidence from detailed groundwater hydrographs and salinity observations, indicating localised canal, river and lake connectivity to groundwater. In the middle and lower catchment, river discharge is dominated by groundwater baseflow during the peak dry season when barrage gates are closed, which contributes to ecological flows for endangered river dolphins and gharial crocodiles. Groundwater residence time tracers indicate active modern recharge in the shallow alluvial aquifer system across the catchment. In the shallow Holocene aquifer elevated arsenic (As), iron (Fe), and manganese (Mn) exceeded WHO drinking water guidelines in a minority of sites, and uranium (U) and fluoride (F) concentrations approach but do not exceed the WHO guideline values. These observations varied across the catchment with higher As, Fe and Mn in the upper and mid catchments and higher U in the lower catchment. Groundwater salinity was typically between 500 and 1000 µS/cm, and isolated higher salinity was due to recharge from flood-plain wetlands and lakes impacted by evaporation. At present, the Gandak catchment has relatively high rainfall and low abstraction, which maintains stable groundwater levels and thus baseflow to the river in the dry season. Potential future threats to groundwater resources, and therefore river ecology due to the sensitivity to changes in baseflow in the catchment, would likely be driven by reductions in local monsoon rainfall, changes in water management practices and increased groundwater use.
9 Sorensen, J. P. R.; Davies, J.; Ebrahim, Girma Y.; Lindle, J.; Marchant, B. P.; Ascott, M. J.; Bloomfield, J. P.; Cuthbert, M. O.; Holland, M.; Jensen, K. H.; Shamsudduha, M.; Villholth, Karen G.; MacDonald, A. M.; Taylor, R. G. 2021. The influence of groundwater abstraction on interpreting climate controls and extreme recharge events from well hydrographs in semi-arid South Africa. Hydrogeology Journal, 29(8):2773-2787. [doi: https://doi.org/10.1007/s10040-021-02391-3]
Groundwater extraction ; Groundwater recharge ; Well hydrographs ; Semiarid climate ; Catchment areas ; Groundwater table ; Rain ; River flow ; Stream flow ; Extreme weather events ; El Nino-Southern Oscillation ; Hydrogeology ; Boreholes ; Spatial distribution ; Land use / South Africa / Limpopo / Mogalakwena Catchment / Sand River Catchment
(Location: IWMI HQ Call no: e-copy only Record No: H050671)
https://link.springer.com/content/pdf/10.1007/s10040-021-02391-3.pdf
https://vlibrary.iwmi.org/pdf/H050671.pdf
https://vlibrary.iwmi.org/pdf/H050671.pdf
(6.26 MB) (6.26 MB)
There is a scarcity of long-term groundwater hydrographs from sub-Saharan Africa to investigate groundwater sustainability, processes and controls. This paper presents an analysis of 21 hydrographs from semi-arid South Africa. Hydrographs from 1980 to 2000 were converted to standardised groundwater level indices and rationalised into four types (C1–C4) using hierarchical cluster analysis. Mean hydrographs for each type were cross-correlated with standardised precipitation and streamflow indices. Relationships with the El Nino– Southern Oscillation (ENSO) were also investigated. The four hydrograph types show a transition of autocorrelation over increasing timescales and increasingly subdued responses to rainfall. Type C1 strongly relates to rainfall, responding in most years, whereas C4 notably responds to only a single extreme event in 2000 and has limited relationship with rainfall. Types C2, C3 and C4 have stronger statistical relationships with standardised streamflow than standardised rainfall. C3 and C4 changes are significantly (p < 0.05) correlated to the mean wet season ENSO anomaly, indicating a tendency for substantial or minimal recharge to occur during extreme negative and positive ENSO years, respectively. The range of different hydrograph types, sometimes within only a few kilometres of each other, appears to be a result of abstraction interference and cannot be confidently attributed to variations in climate or hydrogeological setting. It is possible that high groundwater abstraction near C3/C4 sites masks frequent small-scale recharge events observed at C1/C2 sites, resulting in extreme events associated with negative ENSO years being more visible in the time series.
10 West, C.; Reinecke, R.; Rosolem, R.; MacDonald, A. M.; Cuthbert, M. O.; Wagener, T. 2023. Ground truthing global-scale model estimates of groundwater recharge across Africa. Science of the Total Environment, 858(Part 3):159765. [doi: https://doi.org/10.1016/j.scitotenv.2022.159765]
Groundwater recharge ; Uncertainty ; Models ; Landscape ; Precipitation ; Hydrological modelling ; Land cover ; Vegetation ; Soil properties / Africa
(Location: IWMI HQ Call no: e-copy only Record No: H051607)
https://www.sciencedirect.com/science/article/pii/S0048969722068656/pdfft?md5=3e88e25f89f569b49c0e993956e8d5a4&pid=1-s2.0-S0048969722068656-main.pdf
https://vlibrary.iwmi.org/pdf/H051607.pdf
https://vlibrary.iwmi.org/pdf/H051607.pdf
(2.89 MB) (2.89 MB)
Groundwater is an essential resource for natural and human systems throughout the world and the rates at which aquifers are recharged constrain sustainable levels of consumption. However, recharge estimates from global-scale models regularly disagree with each other and are rarely compared to ground-based estimates. We compare long-term mean annual recharge and recharge ratio (annual recharge/annual precipitation) estimates from eight global models with over 100 ground-based estimates in Africa. We find model estimates of annual recharge and recharge ratio disagree significantly across most of Africa. Furthermore, similarity to ground-based estimates between models also varies considerably and inconsistently throughout the different landscapes of Africa. Models typically showed both positive and negative biases in most landscapes, which made it challenging to pinpoint how recharge prediction by global-scale models can be improved. However, global-scale models which reflected stronger climatic controls on their recharge estimates compared more favourably to ground-based estimates. Given this significant uncertainty in recharge estimates from current global-scale models, we stress that groundwater recharge prediction across Africa, for both research investigations and operational management, should not rely upon estimates from a single model but instead consider the distribution of estimates from different models. Our work will be of particular interest to decision makers and researchers who consider using such recharge outputs to make groundwater governance decisions or investigate groundwater security especially under the potential impact of climate change.
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