Paleo-Geohydrology of Lake Chilwa, Malawi is the Source of Localised Groundwater Salinity and Rural Water Supply Challenges

Attainment of water and sanitation goals: a review and agenda for research

One-fourth of the global population is without basic drinking water and half of the global population lacks sanitation facilities. The attainment of water and sanitation targets is difficult due to administrative, operational, political, transborder, technical, and policy challenges. Conducted after 5 years from the adoption of sustainable development goals by the United Nations reviews the initiatives for improving access, quality, and affordability of water and sanitation. The bibliometric and thematic analyses are conducted to consolidate the outcomes of scientific papers on sustainable development goal 6 (SDG 6). Africa is struggling in relation with water and sanitation goals, having 17 countries with less than 40% basic drinking water facilities and 16 countries with less than 40% basic sanitation facilities. Globally, the attainment of water and sanitation goals will be depended on economic development, the development of revolutionary measures for wastewater treatment, and creating awareness related to water usage, water recycling, water harvesting, hygiene, and sanitation. Behavioral changes are also required for a new water culture and the attainment of water and sanitation goals by 2030.

Assessing groundwater salinity across Africa

In Africa groundwater is the principal source of drinking water (https://washdata.org/) and has significant potential to improve food production as a source of irrigation water. Although volumes of stored groundwater are high when compared to surface water, not all the available groundwater is suitable for irrigation. One of the principal factors that limit the development of groundwater is salinity, but quantitative evidence regarding the scale of salinization in Africa has been lacking. This paper presents an initial analysis of the extent of groundwater salinization in Africa, bringing together groundwater salinity data (n = 12,255) from across the continent. In our dataset c.80% of the samples have electrical conductivity values less than 2000 μS/cm. Samples with high conductivity values of more than 2000 μS/cm are restricted to limited geological and climatic environments. The data reveals salinity does not affect the water security status of most countries in Africa. However, salinity compounds water insecurity issues in arid low groundwater recharge environments. The paper discusses the role of anthropogenic processes such as river valley water resources development, extensive groundwater pumping, inter-basin groundwater transfer, and irrigation in altering the salinity of groundwater bodies. The paper further elucidates the origin of groundwater salinity by critically reviewing the natural and human-induced factors that control the salinization of the various groundwater bodies across Africa. Existing case studies reveal several causes of salinization, including i) human-induced salinization, ii) climate and hydrological change-induced paleo groundwater salinity, iii) rock dissolution, and iv), saltwater encroachment.

Acute health risks to community hand-pumped groundwater supplies following Cyclone Idai flooding

This longitudinal flood-relief study assessed the impact of the March 2019 Cyclone Idai flood event on E. coli contamination of hand-pumped boreholes in Mulanje District, Malawi. It established the microbiological water-quality safety of 279 community supplies over three phases, each comprising water-quality survey, rehabilitation and treatment verification monitoring. Phase 1 contamination three months after Idai was moderate, but likely underestimated. Increased contamination in Phase 2 at 9 months and even greater in Phase 3, a year after Idai was surprising and concerning, with 40% of supplies then registering E. coli contamination and 20% of supplies deemed 'unsafe'. Without donor support for follow-up interventions, this would have been missed by a typical single-phase flood-relief activity. Contamination rebound at boreholes successfully treated months earlier signifies a systemic problem from persistent sources intensified by groundwater levels likely at a decade high. Problem extent in normal, or drier years is unknown due to absence of routine monitoring of water point E. coli in Malawi. Statistical analysis was not conclusive, but was indicative of damaged borehole infrastructure and increased near-borehole pit-latrine numbers being influential. Spatial analysis including groundwater flow-field definition (an overlooked sector opportunity) revealed 'hit-and-miss' contamination of safe and unsafe boreholes in proximity. Hydrogeological control was shown by increased contamination near flood-affected area and in more recent recharge groundwater otherwise of good quality. Pit latrines are presented as credible e-coli sources in a conceptual model accounting for heterogeneous borehole contamination, wet season influence and rebound behavior. Critical to establish are groundwater level - flow direction, hand-pump plume draw, multiple footprint latrine sources - 'skinny' plumes, borehole short-circuiting and fast natural pathway (e.g. fracture flow) and other source influences. Concerted WASH (Water, Sanitation and Hygiene) sector investment in research and policy driving national water point based E. coli monitoring programs are advocated.

Drinking water salinity is associated with hypertension and hyperdilute urine among Daasanach pastoralists in Northern Kenya

Water salinity is a growing global environmental health concern. However, little is known about the relation between water salinity and chronic health outcomes in non-coastal, lean populations. Daasanach pastoralists living in northern Kenya traditionally rely on milk, yet are experiencing socioecological changes and have expressed concerns about the saltiness of their drinking water. Therefore, this cross-sectional study conducted water quality analyses to examine how water salinity, along with lifestyle factors like milk intake, was associated with hypertension (blood pressure BP ≥140 mm Hg systolic or ≥90 mm Hg diastolic) and hyperdilute urine (urine specific gravity <1.003 g/mL, indicative of altered kidney function). We collected health biomarkers and survey data from 226 non-pregnant adults (46.9% male) aged 18+ from 134 households in 2019 along with participant observations in 2020. The salinity (total concentration of all dissolved salts) of reported drinking water from hand-dug wells in dry river beds, boreholes, and a pond ranged from 120 to 520 mg/L. Water from Lake Turkana and standpipes, which was only periodically used for consumption when no other drinking sources are available, ranged from 1100 to 2300 mg/L. Multiple logistic regression models with standard errors clustered on households indicate that each additional 100 mg/L of drinking water salinity was associated with 45% (95% CI: 1.09-1.93, P = 0.010) increased odds of hypertension and 33% (95% CI: 0.97-1.83, P = 0.075) increased odds of hyperdilute urine adjusted for confounders. Results were robust to multiple specifications of the models and sensitivity analyses. Daily milk consumption was associated with 61-63% (P < 0.01) lower odds of both outcomes. This considerable protective effect of milk intake may be due to the high potassium, magnesium, and calcium contents or the protective lifestyle considerations of moving with livestock. Our study results demonstrate that drinking water salinity may have critical health implications for blood pressure and kidney function even among lean, active pastoralists.

Association of Physicochemical Characteristics, Aggregate Indices, Major Ions, and Trace Elements in Developing Groundwater Quality Index (GWQI) in Agricultural Area

The aim of this study was to propose a groundwater quality index (GWQI) that presents water quality data as a single number and represents the water quality level. The development of the GWQI in agricultural areas is vital as the groundwater considered as an alternative water source for domestic purposes. The insufficiency of the groundwater quality standard in Malaysia revealed the importance of the GWQI development in determining the quality of groundwater. Groundwater samples were collected from thirteen groundwater wells in the Northern Kuala Langat and the Southern Kuala Langat regions from February 2018 to January 2019. Thirty-four parameters that embodied physicochemical characteristics, aggregate indicator, major ions, and trace elements were considered in the development of the GWQI. Multivariate analysis has been used to finalize the important parameters by using principal component analysis (PCA). Notably, seven parameters-electrical conductivity, chemical oxygen demand (COD), magnesium, calcium, potassium, sodium, and chloride were chosen to evaluate the quality of groundwater. The GWQI was then verified by comparing the groundwater quality in Kota Bharu, Kelantan. A sensitivity analysis was performed on this index to verify its reliability. The sensitivity GWQI has been analyzed and showed high sensitivity to any changes of the pollutant parameters. The development of GWQI should be beneficial to the public, practitioners, and industries. From another angle, this index can help to detect any form of pollution which ultimately could be minimized by controlling the sources of pollutants.

True 2-D Resistivity Imaging from Vertical Electrical Soundings to Support More Sustainable Rural Water Supply Borehole Siting in Malawi

To improve borehole siting for rural water supply, an advanced resistivity method was adapted for developing country use and demonstrated in Malawi. The method was designed to be low cost, developing-country accessible, efficient. It allows single or multiple operators to acquire the multiple vertical electrical soundings (VESs) required that are inverted together in 2-D, to give a true cross-section of subsurface resistivity. Application at four sites generated true cross-sections of subsurface resistivity to around 100 m depth relevant to groundwater-resource investigation. A wide range of (hydro)geological features was identified, including fractured/weathered basement, gneiss domes, well-developed fault zones and several types of deltaic deposits. Imaging performance appears comparable to that of 2-D surface ERT (electrical resistivity tomography) that uses more expensive equipment, often unaffordable in developing countries. Based on the subsurface configurations determined and hydrogeological conceptualisation subsequently undertaken, the local aquifer potential could be evaluated, thereby providing a decision-making basis for future borehole siting at the sites surveyed. The technology is far superior to conventional 1-D VES, electromagnetic profiling or magnetic profiling currently used for borehole siting in Malawi. Technology adoption currently under consideration nationally would make use of existing VES capacity and permit much improved targeting of aquifer resource, more sustainable siting of boreholes and greater future resilience of Malawi’s rural water-supply infrastructure.