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As rural African communities experience more frequent and extreme droughts, it is increasingly important that water supplies are climate resilient. Using a unique temporal dataset we explore rural water supply (n = 5196) performance during the 2015–16 drought in Ethiopia. Mean functionality ranged from 60% for motorised boreholes to 75% for hand-pumped boreholes. Real-time monitoring and responsive operation and maintenance led to rapid increases in functionality of hand-pumped and, to a lesser extent, motorised boreholes. Increased demand was placed on motorised boreholes in lowland areas as springs, hand-dug-wells and open sources failed. Most users travelled >1 h to access motorised boreholes but <30 min, increasing to 30-60 mins, for hand-pumped boreholes. Boreholes accessing deep (>30 m) groundwater performed best during the drought. Prioritising access to groundwater via multiple improved sources and a portfolio of technologies, such as hand-pumped and motorised boreholes, supported by responsive and proactive operation and maintenance, increases rural water supply resilience. The authors compared the performance of a range of rural water supply types during drought in Ethiopia. They show that prioritising access to groundwater via multiple improved water sources and technologies, such as hand-pumped and motorised boreholes, supported by monitoring and proactive operation and maintenance increases rural water supply resilience. [ABSTRACT FROM AUTHOR]

Groundwater quality study of the Birimian, Cape Coast granitoid and the Densu River have been carried out using Water Quality Index (WQI) and multivariate statistics with the aim of determining their suitability for drinking and irrigation. The results showed that the Cape Coast granitoid generally had elevated values of dissolved ions as compared to the Birimian and surface waters. The WQI values were found ranging from 0 to 50 belonging to 'excellent' and 'good' water quality. The visualization of the WQI distributions using GIS software suggests point source pollution to areas of deteriorating water quality. Chemical indices like percentage of sodium (Na%), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), and permeability index (PI) indicate that the groundwater in the study area are suitable for irrigation. Cluster and Principal Component Analysis with varimax rotation were also used as a complementary tool to help organize and interpret the chemical analysis. Four principal components with eigen-values greater than unity accounting for 73.16% of the variability in the data were delineated. The factor score plot also separated the polluted areas and identified areas with potential deteriorating water quality. Even though the geology is the main factor controlling the presence of the dissolved ions, the study shows an increase in anthropogenic contributions in some areas. [ABSTRACT FROM AUTHOR]

Understanding spatial and temporal distribution of water resources has an important role for water resource management. To understand water balance dynamics and runoff generation mechanisms at the Gilgel Abay catchment (a major tributary into lake Tana, source of Blue Nile, Ethiopia) and to evaluate model transferability, catchment modeling was conducted using the conceptual hydrological model HBV. The catchment of the Gigel Abay was sub-divided into two gauged sub-catchments (Upper Gilgel Abay, UGASC, and Koga, KSC) and one ungauged sub-catchment. Manual calibration of the daily models for three different catchment representations (CRs): (i) lumped, (ii) lumped with multiple vegetation zones, and (iii) semi-distributed with vegetations zone and elevation zones, showed good to satisfactory model performance (Nash-Sutcliffe efficiency values, Reff>0.75 and >0.6, respectively, for UGASC and KSC). The change of the time step to fifteen and thirty days resulted in very good model performances in both sub-catchments (Reff>0.8). The model parameter trans ferability tests conducted on the daily models showed poor performance in both subcatchments, whereas the fifteen and thirty days models yielded high Reff values using transferred parameter sets. This together with the sensitivity analysis carried out after Monte Carlo simulations (1 000 000 model runs) per CR explained the reason behind the difference in hydrologic behaviors of the two sub-catchments UGASC and KSC. The dissimilarity in response pattern of the sub-catchments was caused by the presence of dambos in KSC and differences in the topography between UGASC and KSC. Hence, transferring model parameters from the view of describing hydrological process was found to be not feasible for all models. On the other hand, from a water resources management perspective the results obtained by transferring parameters of the larger time step model were acceptable. [ABSTRACT FROM AUTHOR]

Fluoride is a common inorganic contaminant of geogenic origin around the world. Anthropogenic sources of fluoride could also contribute to increased fluoride concentrations in groundwater, although they have not been well-documented. This paper presents soil batches and unsaturated column experiments on fluoride-enriched recharge water percolating from a urine-polluted soil in an area where fluorosis is endemic. Results from the polluted soil collected near a main street in Addis Ababa (Ethiopia) are compared with an unpolluted soil collected in a garden inside the university campus, located 50 m from the polluted one. Soils were sampled at the end of the dry season and after the first intense rainfall at the beginning of the wet season. The objectives of the study were to evaluate the anthropogenic fluoride enrichment in urban recharge due to unmanaged human excretions along the streets and model recharge water fluxes and solutes leaching to evaluate the reactivity of dissolved species. Batch experiments found extremely high fluoride (42.1 ± 5.2 mg/kg) and urea (89.5 ± 8.1 mg/kg) concentrations in polluted soil before the rainy season. The fluoride concentration in the polluted soil was more than one order of magnitude higher than that recorded in the uncontaminated soil. This study proved that in areas where the population is subject to a large fluoride daily intake, recharge waters extremely enriched in fluoride can be leached from urine-contaminated soils in urban environments. The proposed methodology could be applied for a first screening for the anthropogenic sources of fluoride in urban recharge. [ABSTRACT FROM AUTHOR]