Groundwater is a key water resource. In Malawi it provides 82% of domestic, agricultural, and industrial water needs. However, despite its central importance to meeting social and economic targets, with over 14 million people reliant on groundwater to meet their everyday needs, the ‘unseen’ nature of groundwater makes management a challenge. Furthermore, minimal groundwater monitoring and measurement limit understanding of Malawi’s of water security. To guide water management policy and practice, comprehensive modelling of Malawi’s water resources, accounting for groundwater, is necessary. Here, to the best of our knowledge, we present the first process-based model of groundwater storage for the Lake Malawi Shire River Basin,which covers 94% of Malawi’s surface area, confirming prior estimates of groundwater storage.We apply a global hydrological model, the Community Water Model (CWatM), to Malawi. To effectively represent Malawi’s water resources, we couple a high-resolution CwatM (5 arc minute resolution) with MODFLOW (5km resolution), enabling a high-resolution, national surface and groundwater model. Semi-structured stakeholder interviews were conducted to accurately represent Malawi’s water governance, identifying key adjustments that reflect national water resources. Model modifications were implemented based on stakeholder engagement. Notably, we implement model modification to account for small-holder agriculture and ‘dambo’ wetlands. National characteristics of water and sanitation were also included; the model was developed to include pit-latrine sanitation, used by over 90% of the population. Spatial variation domestic water use, both source and quantity, between urban and rural areas was also incorporated. Such model modifications significantly improved model performance, we suggest similar developments should be considered in modelling national water resources in other southern-African countries. Basin-wide scale model validation was undertaken by comparison with remote sensing observations of evapotranspiration, precipitation, and changes in total water storage (using GRACE Satellite data). Model calibration was undertaken by comparison to Global Data Runoff Centre (GRDC) discharge data.We model that 660km³ of available groundwater is stored within aquifer units in Malawi (the currently available estimate of groundwater storage in Malawi is between 96.7 and 1,108 km³). Our model shows a consistent decline in groundwater levels since 1960 (the beginning of our study period). In total, we estimate a decline of 11.6km³ in groundwater storage in Malawi since 1960, raising significant concerns for future water security in the country. Not only does this model provide unprecedented insight into Malawi’s water security, particularly regarding the unseen but critical groundwater resource, further model development will enable forecasting of future water security issues under climate and socio-economic change.

Study region: The study is conducted in the transboundary Komadugu-Yobe Basin, Lake Chad region, a critical groundwater resource shared across national boundaries of Nigeria and Niger Republic. Study focus: The research investigates geochemical evolution and sources of chemical constituents in groundwater through an integrated methodology that integrates geochemical modeling, molar ratios, bivariate plots, and chemometric analysis. Groundwater samples (n = 240) were collected during wet and dry seasons to identify seasonal variations and the impact of geogenic and anthropogenic processes on groundwater quality. New hydrological insights: The findings revealed that Cl- and NO3- are associated with anthropogenic pollution. The Principal Component Analysis identified three main components associated with geogenic and anthropogenic processes, agricultural pollution, and mineral weathering. Hierarchical Cluster Analysis highlighted geogenic, anthropogenic, and evaporative influences. Groundwater in the basin is predominantly of Ca-HCO3 and Na-Cl types and is significantly undersaturated with calcite, dolomite, and fluorite, though seasonal variations show saturation in some samples. Elevated partial pressures of CO2 (pCO2) above atmospheric pCO2 in nearly all samples suggests active biogeochemical processes. Moreover, Gibbs plots, molar ratios, and bivariate plots, along with chloroalkaline indices (CAI-I & CAI-II) confirms influence of mineral weathering and ion exchange reactions within the aquifer system. Few locations show evaporation during the dry season. This study provides valuable insights for sustainable management of groundwater resources in semi-arid and arid regions.

This study evaluates the quality and vulnerability of groundwater within the Nakivale Sub-catchment of the transboundary Lake Victoria Basin in Southwestern Uganda. Groundwater quality assessment focuses on its suitability for both drinking and agricultural uses. Hydrochemical analysis of 19 groundwater samples revealed that 90% comply with World Health Organization drinking water standards, although localized contamination was noted, particularly in terms of total iron, nitrate, potassium, magnesium, and sulfates. The drinking groundwater quality index shows that over 90% of the samples fall within the good-to-excellent quality categories. Elevated nitrate levels and chloride–bromide ratios indicate human impacts, likely due to agricultural runoff and wastewater disposal. For irrigation, Sodium Adsorption Ratio analysis revealed medium-to-high salinity hazards in the region, while Sodium Percentage and other parameters indicated low-to-moderate risks of soil degradation. DRASTIC vulnerability assessments identified low contamination risks due to impermeable geological layers, steep terrain, slow groundwater recharge, deep aquifer depth, and clayey soil cover. These findings emphasize the need for conjunctive water resource management, including improved groundwater quality monitoring, public education on sustainable practices, and protective measures for recharge zones and areas highly susceptible to contamination. By addressing these issues, this study aims to preserve groundwater resources for domestic and agricultural use, ensuring long-term sustainability in the region.

Railway embankment slopes are exposed to natural hazards such as excess rainfall, floods, earthquakes, and lake water/groundwater level variations. These are generally considered during the design, construction, and maintenance periods of the embankment. In this study, combined laboratory test methods and a computational approach were applied to assess the effect of groundwater level changes on the railway embankment. The Plackett–Burman (PBD), Box–Behnken design response surface methodology (BBD-RSM), and an artificial neural network (ANN) were used to predict the behavior of the embankment soil hydromechanical properties to determine the integrity of the embankment as water level fluctuates under varied seasonal conditions. The results show that the seepage line is concave during the rising water level (RWL) period, and the railway slope’s static stability factor surges and then stabilizes. Further analysis found that the slope’s stability is largely affected by some of the hydromechanical properties of the soil embankment material, such as the internal friction angle (ϕ), soil density (ρs), and cohesion (c). The second-order interaction factors c x s, x s, and s2 also affect the stability factor. It was observed that the four most sensitive parameters under both falling water level (FWL) and RWL conditions are ϕ, ρs, c, and rate of fall/rise in water level (H). The statistical evaluation of the RSM model produced R2 values of 0.99(99) and 0.99, with MREs of 0.01 and 0.24 under both RWL and FWL conditions, respectively, while for ANN, they produced R2 values of 0.99(99) and 0.99(98), with MRE values of 0.02 and 0.21, respectively. This study demonstrates that RSM and ANN performed well under these conditions and enhanced accuracy, efficiency, iterations, trial times, and cost-effectiveness compared to full laboratory experimental procedures.

Rainfall is changing in intensity and abundance for much of the world as a result of global climate change. Rwanda has been negatively affected by a changing climate, exacerbated by human impact on land and water resources. In most parts of the country, the rainfall pattern has changed over the last decades resulting in both enhanced flooding and water shortage/scarcity in much of the country, especially in the Capital City of Kigali and peripheries which is the main economic hub of the country with strong links to the East African region. Changes in precipitation have affected agricultural production, hydropower production, and water supplies, and has been a result of increased flash floods in the city. This study developed a new predictive model of rainfall patterns in the City of Kigali (CoK) in the Republic of Rwanda using evolutionary methodologies that apply machine learning techniques of Fuzzy Inference Systems (FIS) trained via Genetic Algorithms, Neuro Network Systems and a comparative Support Vector Machine tool, and assessment downscaled climate change combinations with predicted rainfall patterns. The models were calibrated and validated using measured rainfall data in the City of Kigali from 1991 through 2023. The model results show the developed Geno Fuzzy Inference System (GENOFIS) model performed better than the Adaptive Neuro-Fuzzy Inference System (ANFIS) and Support Vector Machine (SVM) models. The Coefficient of Efficiency (CE), and Root Mean Square Error (RMSE) were used as diagnostic measures for model performance evaluation. Models generated with GENOFIS are therefore recommended for rainfall and related prediction patterns in the City of Kigali for climate change adaptation and resilience policy and planning.

Despite widespread access to basic sanitation in Malawi, over 75% of the population lacks improved sanitation facilities. This national study investigates the resilience of pit-latrines across Malawi, focusing on the relationship between construction quality, facility lifespan, and collapse frequency. A survey of 268,000 pit-latrines revealed that high-quality latrines (lined and with a slab) collapse three times less frequently than low-quality latrines and last significantly longer. However, cost barriers remain substantial, with high-quality latrines costing five times more than low-quality facilities. Even when accounting for their extended lifespan, the annual cost of high-quality facilities is almost double that of low-quality options, highlighting a key financial challenge for widespread adoption. Pit-latrine emptying, while offering a potential solution to extend the lifespan of latrines, is rarely practiced due to its high costs and cultural resistance. Manual emptying, the most common method, raises health and environmental concerns, while emptying costs remain prohibitively high for many households. The study emphasises the need for significant investment in resilient sanitation infrastructure, promotion of affordable emptying services, and the development of faecal waste management systems. Addressing these challenges is essential to ensuring equitable access to safe and sustainable sanitation in Malawi, ensuring climate resilience and sanitation justice.

Menstrual hygiene management (MHM) forms a critical component of ensuring access to adequate and equitable sanitation for all, as outlined in SDG 6.2. Despite its importance, little is known about MHM in Malawi, particularly at a household level. Through a household survey of MHM within 2 districts, we evaluated the type of menstrual absorbents used by people who menstruate. Reusable cloths/rags were the most used menstrual absorbent, used by 79.5% of respondents, whilst disposable absorbents, such as tampons and sanitary pads, were used by 18.6% of respondents. Appropriate MHM also incorporates adequate management of MHM materials, including the washing and drying of reusable menstrual absorbents. We evaluated the cleaning of reusable menstrual absorbents; most respondents (90.1%) reported appropriate washing of menstrual absorbents using soap and water, however only 20.3% reported that menstrual absorbents were dried outside in the sun (as is best practise) with most reporting that reusable menstrual absorbents were dried inside their homes. Our findings highlight the need for improved MHM within Malawi, not only in the access and affordability of appropriate menstrual absorbents but also the promotion of appropriate washing and drying of menstrual absorbents. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was funded by the Scottish Government under the Scottish Government Climate Justice Fund Water Futures Programme research grant HN-CJF-03 awarded to the University of Strathclyde (R.M. Kalin). Funding was also received from the Scottish Government for the joint PhD studentship of R.G.K Hinton between the James Hutton Institute and the University of Strathclyde. The data collection process was funded by CARE with the financial support of the Government of Canada provided through Global Affairs Canada. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Not Applicable The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Informed consent was obtained from all subjects involved in the study. All data collected was in line with the Government of Malawi ethics and was agreed with each participant. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Not Applicable I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Not Applicable I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Not Applicable Confidential data were provided by the Government of Malawi and CARE. All data summarised is provided here.

Groundwater contamination poses significant challenges to public health and sustainable development in Malawi, where approximately 80 % of the population relies on groundwater sources for drinking water. This study investigates the presence and drivers of nitrate and E. coli contamination in groundwater used for drinking. Analysis was conducted on results from 3388 boreholes/tube wells for nitrate contamination and 2418 drinking water sources drawn from groundwater for E. coli contamination. Overall, 6.11 % and 57.2 % of water-points did not meet WHO guidelines for safe drinking water quality for nitrate and E. coli contamination, respectively. Through a mixed-method approach, utilizing generalised linear mixed models and random forest regression modelling, the study identifies factors relating to sanitation usage as critical drivers of both nitrate and E coli contamination. Pit-latrine usage was identified as a particularly important factor in contamination; accounting for pit latrine density specifically, rather than population density, resulted in better model prediction for both nitrate and high E. coli contamination indicating that consideration of the specific type of sanitation is important in predicting water quality. In addition, a stable isotope tracer analysis method to validate predictions and monitor nitrate in drinking water was piloted, identifying human waste as a likely source of nitrate contamination. Overall, this study underscores the urgency of addressing sanitation-related contamination of drinking water sources to ensure access to safe drinking water in low-income settings.

This study characterized groundwater resources for the Nakivale sub-catchment of the transboundary Victoria Basin in Uganda using classical hydrochemical and stable isotopic approaches. Groundwater in the study area is essential for domestic, agricultural, and industrial uses. As a sub-domain of the larger Victoria Basin, it also plays a crucial role in shaping the hydrological characteristics of this vital transboundary basin, both in terms of quality and quantity fronts. This makes its sustainable management and development vital. The predominant groundwater type is Ca-SO4, with other types including Ca-HCO3, Na-Cl, Na-HCO3, and Ca-Mg-SO4-Cl. Hydrochemical facies analysis highlights the importance of rock–water interactions in controlling groundwater chemistry, mainly through incongruent chemical weathering of Ca-rich plagioclase feldspars and the oxidation of sulfide minerals, such as pyrite, which are prevalent in the study area. Groundwater recharge is primarily influenced by the area’s topography, with recharge zones characterized by lineament networks, located in elevated areas. Stable isotope analyses indicate that groundwater mainly originates from local precipitation, while tritium data suggest the presence of both recent and older groundwater (likely over 20 years old). The study’s comprehensive approach and findings contribute significantly to the understanding of groundwater systems in the region, thus providing valuable insights for policymakers and stakeholders involved in water resource management and development strategies.

The assessment of hydrochemical characteristics and groundwater quality is crucial for environmental sustainability in developing economies. This study employed hydrogeochemical analysis, geospatial analysis, and groundwater quality index to assess hydrogeochemical processes and quality of groundwater in the Komadugu-Yobe basin. The pH, total dissolved solids (TDS), and electrical conductivity (EC) were assessed in situ using a handheld portable electrical conductivity meter. The concentrations of the major cations (Na+, Ca2+, Mg2+, and K+), were analyzed using inductively coupled plasma optical emission spectroscopy (ICP-OES). The major anions (chloride, fluoride, sulfate, and nitrate) were analyzed via ion chromatography (IC). Total alkalinity and bicarbonate were measured in situ using a HACH digital alkalinity kit by the titrimetric method. Hydrochemical results indicate some physicochemical properties of the groundwater samples exceeded the maximum permissible limits as recommended by the World Health Organization guidelines for drinking water. Gibbs diagrams indicate rock–water interaction/rock weathering processes are the dominant mechanisms influencing the groundwater chemistry. Groundwater is predominantly Ca2+-Mg2+-HCO−3 water type, constituting 59% of the groundwater samples analyzed. The groundwater quality index (GWQI) depicted 63 and 27% of the groundwater samples as excellent and good water types for drinking purposes, respectively. This study further relates the interaction between geology, hydrochemical characteristics, and groundwater quality parameters. The results are essential to inform a sustainable management strategy and protection of groundwater resources.

Reliance on groundwater is outpacing natural replenishment, a growing imbalance that requires detailed and multi-faceted water resource understanding. This study integrated water-stable isotopes and hydrogeochemical species to examine hydrogeochemical processes during groundwater recharge and evolution in the Lake Malawi basin aquifer systems. The findings provide insights into groundwater source provenance, with non-evaporated modern precipitation dominating recharge inputs. Grouped hydrochemical facies exhibit five groundwater water types, prominently featuring Ca-Mg-HCO3. Modelled hydrogeochemical data underscore dominant silicate dissolution reactions with the likely precipitation of calcite and/or high-Mg dolomitic carbonate constrained by ion exchange. Isotope hydrology reinforces water resource system conceptualisation. Coupled isotopic-hydrogeochemical lines of evidence reveal a discernible spatial-seasonal inhomogeneity in groundwater chemical character, revealing a complex interplay of meteoric water input, evaporative effects, recharge processes, and mixing dynamics. Findings show that measurable nitrate across Malawi highlights a widespread human impact on groundwater quality and an urgent need for detailed modelling to predict future trends of nitrate in groundwater with respect to extensive fertiliser use and an ever-increasing number of pit latrines and septic systems arising from rapid population growth. This study not only refined the Lake Malawi basin aquifer systems conceptualisation but also provided isotopic evidence of groundwater and lake water mixing. This study sets a base for groundwater management and policy decisions in support of the Integrated Water Resources Management principles and Sustainable Development Goal 6 objectives for groundwater sustainability in the transboundary Lake Malawi basin.

Pit-latrines are central to achieving UN Sustainable Development Goal 6 (SDG 6) of ensuring "clean water and sanitation for all". Unless safely managed, pit-latrines result in groundwater contamination, which increases morbidity and mortality. Despite this, there have been no long-term spatial projections of future pit-latrine contamination risks. National survey data of over 100,000 water-points and 260,000 pit-latrines in Malawi was used to generate a novel, high-resolution model of pit-latrines from 2020 to 2070 under five population scenarios. The results here are presented as a 'business as usual' scenario of population growth and pit-latrine usage, predicting a three-fold increase in the number of current water-points at risk of short-distance microbial pit-latrine contamination between 2020 and 2070, with a seven-fold increase in number at the highest risk of contamination. Current nitrogen loading into pit-latrines is comparable to national fertiliser application. The model predicts 8.2 mega-tonnes of faecal nitrogen will be disposed of into subsequently abandoned pit-latrines between 2020 and 2070. Change is necessary to prevent SDG6's push for sanitation undermining its goal of clean water.

Abstract Pit-latrines are central to achieving SDG6, “clean water and sanitation for all”. Unless safely managed, pit-latrines result in groundwater contamination, which increases morbidity and mortality. Despite this, there have been no long-term spatial projections of future pit-latrine contamination risks. National survey data of over 100,000 water-points and 260,000 pit-latrines in Malawi was used to generate a novel, high-resolution model of pit-latrines from 2020–2070 under 5 population, and 3 sanitation policy, scenarios. The ‘business as usual’ model predicts a three-fold increase in the number of water-points at risk of microbial pit-latrine contamination between 2020–2070, with a seven-fold increase in the highest contamination risks. Current nitrogen loading into pit-latrines is comparable to national fertiliser application. The model predicts 8.2 mega-tonnes of faecal nitrogen will be disposed of into subsequently abandoned pit-latrines between 2020–2070. Guided intervention is necessary to prevent SDG6’s push for sanitation undermining its goal of clean water.

<p>Providing adequate and equitable sanitation to all by 2030 is central to achieving Sustainable Development Goal 6 (SDG6). Pit-latrines provide a low-cost, accessible form of sanitation, there has, therefore, been a significant increase in the rapidly growing Malawian population using pit latrines, largely driven by a reduction in open defecation. Whilst open defecation reduction is critical in managing waterborne pathogens and other contaminants, pit latrines can also result in both microbial and nutrient contamination of groundwater; faecal contamination of groundwater, resulting in contaminated boreholes, has already been documented in Malawi.</p> <p>To forecast the level of pit-latrine usage in Malawi, we evaluate the trends in Malawian sanitary provision using linear modelling to estimate that currently 500,000 people gain access to sanitation in Malawi every year, requiring approximately 93,000 new pit-latrines to be constructed annually to accommodate this shift. The associated increase in pit-latrine density creates a heightened threat of borehole contamination and a key public health concern.</p> <p>We also examine the nature of pit-latrine management and usage, presenting the results of a national survey of over 200,000 sanitary facilities. Whilst pit-latrines are usually associated with faecal contaminants, we found that 82.3% of pit-latrines had materials other than faecal waste deposited including rubbish, plastics, and oils; these present a danger of micropollutant contamination. Furthermore, we find that sustainable practises to manage waste deposited in pit-latrines, such as pit-latrine emptying, have low adoption.</p> <p>Pit-latrine usage is already causing groundwater contamination in Malawi, this will only be exacerbated by our projected increase in pit-latrine usage as Malawi manages a growing population and actively pushes to eliminate open defecation.</p> <p>This research is thanks to research and collaboration with the Government of Malawi with funding by the Scottish Government under the Scottish Government. Climate Justice Fund Water Futures Programme.</p>

Flood analyses when using a GIS-based integrated approach have been successfully applied around the world in large-sized watersheds. This study employed hydrological-hydraulic modeling to analyze flash floods by integrating HEC-HMS, HEC-RAS, and ArcGIS software for flood evaluation and control in a micro-watershed in the Samaru River, Nigeria. The watershed boundaries, its characteristics (soil and land use), the topographical survey, and the intensity duration frequency curve (IDF) of the study area were produced using data-driven techniques. The HEC-HMS model was used to derive the peak discharges for 2-, 5-, 10-, 25-, 50-, 100-, and 200-year return periods with the frequency storm method. Afterward, the water surface profiles for the respective return periods were estimated using the HEC-RAS hydrodynamic model. The simulated design flood for the 2-, 5-, 10-, 25-, 50-, 100-, and 200-year return periods at the reference location (the NUGA gate culvert) were 3.5, 6.8, 9.1, 12.1, 14.3, 16.6, and 19.0 m3/s, respectively, while those at the watershed outlet for the respective return periods were 7.5, 14.9, 20.3, 27.3, 32.6, 38.0, and 43.5 m3/s, respectively (with a water height of 0.9 m, 1.1 m, 1.3 m, 1.33 m, 1.38 m, 1.5 3m, and 1.8 m, respectively), at the NUGA gate culvert cross-section. The maximum water depths of about 0.9 m and 1.0 m were recorded in the right and left overbanks, which were similar to the simulated water depth for the 2- and 5-year return periods. Hence, for the smart control of floods passing through the river and major hydraulic structures, a minimum design height of 1.50 m is recommended. For the most economic trapezoidal channel section, a normal depth of 1.50 m, a bottom width of 1.73 m, a top width of 3.50 m, and a free board of 0.30 m is proposed to curb the overtopping of floods along the channel sub-sections. The findings of this study could help hydraulic engineers minimize flooding in streams and rivers overbanks in a micro-watershed.

The assessment of groundwater quality and its geochemical mechanism is crucial for the sustainable use and management of groundwater resources in arid and semi-arid regions of developing nations. 120 groundwater samples were collected from the Komadugu-Yobe basin to determine its overall quality and the factors that controls the geochemical mechanisms of the groundwater of the study region. The pH, electrical conductivity (EC), and total dissolved solids (TDS) of the groundwater samples were analysed in situ using a handheld (Model 99720 pH/Conductivity meter). The concentrations of Na+, Ca2+, Mg2+, and K+ were analyzed using ICP-OES, iCAP 6200, Thermo Fisher Scientific while Cl-, F-, SO42-, and NO3- were analysed using Ion Chromatography (Metrohm 850 Professional IC). Moreover, the total Alkalinity and bicarbonate were determined using KONE Aquakem v. 7.2.AQ2 equipment by titrimetric method. The hydrochemical analysis results reveals that less than 10% of the groundwater samples exceeded the maximum permissible limits for Electrical conductivity, total dissolved solids, total hardness, sodium, potassium, calcium, magnesium, chloride, sulfate, and fluoride for drinking purposes as recommended by the world Health Organization (WHO, 2018) standards except for bicarbonate and nitrate. The Gibbs diagrams reveals that rock-weathering/rock water interaction is the dominant mechanism controlling groundwater of the study region. However, the chemical relationships in Piper trilinear plots identified Ca2+-Mg2+- HCO-3 water type predominated the study area constituting about 59% of the groundwater samples collected. The findings of the study are paramount for implementing a sustainable management strategy of groundwater resources in the Komadugu-Yobe basin towards the realization of Goal 6 of sustainable development goals.Keywords: Groundwater, Komadugu-Yobe basin, Geospatial analysis, Water quality, Rock-water interaction

Ensuring access to adequate and equitable sanitation and ending open defecation by 2030 is the focus of Sustainable Development Goal 6.2 (SDG6.2). We evaluated Malawi’s progress towards SDG 6.2 (specifically the goal to end open defecation), presenting the results of a national survey of over 200,000 sanitary facilities and evaluating their management. Based on non-linear population dynamics, we used a linear model to evaluate the reduction in open defecation between 1992–2018, and to project whether Malawi can meet the SDG target to end open defecation by 2030 under multiple scenarios of population growth. Whilst Malawi has made considerable progress in providing sanitary provision for the population, we estimate that, at the current rate of the provision of sanitary facilities, Malawi will not reach SDG 6.2 by 2030 under any of the modelled socioeconomic scenarios. Furthermore, we compare the estimates of the extent of sanitary provision classed as improved from multiple surveys, including the USAID Demographic and Health (DHS) Surveys and Government of Malawi Census data. We conclude that some of the surveys (particularly the 2015/16 DHS) may be overestimating the level of improved sanitary provision, and we hypothesize that this is due to how pit-latrines with earth/sand slabs are classed. Furthermore, we examine the long-term sustainability of pit-latrine use, investigating the challenge of pit-latrine abandonment and identifying pit-latrine filling as a cause of the abandonment in 30.2% of cases. We estimate that between 2020–2070, 31.8 (range 2.8 to 3320) million pit-latrines will be filled and abandoned, representing a major challenge for the safe management of abandoned latrines, a potential for long-term impacts on the groundwater quality, and a significant loss of investment in sanitary infrastructure. For Malawi to reach SDG 6.2, improvements are needed in both the quantity and quality of its sanitary facilities.

AbstractWater is a finite natural resource. Zero Water Day(s) scenarios are challenging people and communities in Europe and worldwide. The public health community must seize the opportunity to prepare for Zero Water Day(s) through strengthening capacity and capability to respond to rapidly emerging emergencies as well as protected crises. Collaboration across sectors on water conservation and public health is key to tackling the consumptive environment and extractive economic systems.

Flood risk management is crucial for climate change resilience. The Hadejia River basin is known for severe and frequent floods, which have destroyed houses and farmlands and claimed many lives. This study developed a GIS-based flood risk and vulnerability mapping assessment using the Analytical Hierarchical Process (AHP) to outline scenarios that reduce risk and vulnerability associated with floods in the Hadejia River basin. The risk mapping of the basin integrated seven hydro-geomorphological indicators influencing extreme events (elevation, mean annual rainfall, slope, distance from rivers, soil type, and drainage density) and six socio-economic vulnerability indicators (population density, female population density, literacy rate, land use, employment rate, and road network) using a multi-criterion analysis. The average annual rainfall data of 36 years (1982–2018) were used for flood plain mapping in this study. Combining the flood hazard and socio-economic vulnerability indices of the basin revealed high-to-very high flood risk in the downstream and central upstream portions of the basin, which cover about 43.4% of the basin area. The local areas of Auyo, Guri, Hadejia, Ringim, Kafin Hausa, and Jahun were identified as zones at a very high flood risk. The study also revealed that flood hazard and vulnerability indicators have different influences on flood risk. The validated results resonate with the records of previous flood distribution studies of the basin. This research study is significantly important for developing strategic measures and policy revision through which the government and relief agencies may reduce the negative impact of floods in the Hadejia River basin.

Hidden hot springs likely impact rural water supplies in Malawi's Rift Valley with excess dissolved fluoride leading to localised endemic severe dental fluorosis. Predicting their occurrence is a challenge; Malawi's groundwater data archive is sporadic and incomplete which prevents the application of standard modelling techniques. A creative alternative method to predict hidden hot spring locations was developed using a synthesis of proxy indicators (geological, geochemical, dental) and is shown to be at least 75% effective. An exciting collaboration between geoscientists and dentists allowed corroboration of severe dental fluorosis with hydrogeological vulnerability. Thirteen hidden hot springs were identified based on synthesised proxy indicators. A vulnerability prediction map for the region was developed and is the first of its kind in Malawi. It allows improved groundwater fluoride prediction in Malawi's rift basin which hosts the majority of hot springs. Moreover, it allows dentists to recognise geological control over community oral health. Collaborative efforts have proven mutually beneficial, allowing both disciplines to conduct targeted research to improve community wellbeing and health and inform policy development in their respective areas. This work contributes globally in developing nations where incomplete groundwater data and vulnerability to groundwater contamination from hydrothermal fluoride exist in tandem.