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This paper analyses and assesses water losses in the Kribi Water Distribution Network (KWDN) in order to constructively feed the debate on the most effective ways to reduce water losses in urban water distribution networks in Sub-Saharan Africa. The analysis of water losses was conducted based on numerous indices (failure intensity index, percentage ratio of water loss, and unit water loss per capita) and indices recommended by the International Water Association (real leakage balance, non-revenue water basic, and infrastructure leakage index). The results show that the failure intensity index increased significantly from 0.15 in 2010 to 0.31 in 2017, while the water loss indices have achieved a medium performance. The unit water loss performed well in 2013, 2015, and 2017. The Non-Revenue Water Basic Index was above the threshold for well-performing at 23% between 2010 and 2017. The real leakage balance (RLB) index indicated that the KWDN performed well (RLB < 100 dm3/connection/day). Results also suggest that the Infrastructure Leakage Index (ILI) ranged from 1.70 to 2.59, which corresponds to performance category B. This range of values indicates the need for improvement to enhance profitability with better network pressure management, active leakage control, and network maintenance. However, this assessment represents only a current snapshot of the water loss situation in the KWDN and should be conducted at regular intervals to track changes in overall and local conditions.

Shallow groundwater of unknown quality, mineralisation and recharge processes is a major source of water supply to most households in the informal settlements in the Bonaberi (Douala IV) district, Cameroon. Accordingly, this study (December 2018) investigated the quality, hydrogeochemical controls, and recharge mechanism of 18 shallow groundwater (< 10 m deep) and 6 surface water sources in Bonaberi. Apart from Na+, Cl−, SO42−, Fe, Mn, and Al in some water sources, all other analysed chemical parameters were within the WHO (2011) guidelines for drinking water. The order of major ions abundance (meq/l) in the studied water was Na2+> Cl−> Ca2+> HCO3−> SO42> K+> NO3−> Mg2+while the trace element abundance (ppb) was Ti > Fe > Mn > Sr > Ba > Al > Rb > Zn > As > Se > Cr. Two main water types identified in Bonaberi are Na-Cl and mixed Ca-Na-HCO3. Mineral weathering and leaching from pit toilets and waste dumps are major factors influencing groundwater composition. Stable isotopes show overlaps in surface water and groundwater, indicating hydraulic connectivity. The narrow ranges in δ18O values of the shallow groundwater suggest good water mixing and a homogenous aquifer. The major source of groundwater recharge is rainfall occurring by direct diffused rapid recharge through the permeable alluviums. This recharge favours the leaching of pollutants from residential pit toilets into the shallow aquifer. However, the groundwater mixing and its dilution by heavy rains results in relatively low NO3−and Cl−concentrations in the water though relatively higher in densely populated areas. The shallow aquifer in Bonaberi is vulnerable to pollutants generated within the city. Thus, drilling deep boreholes (after detailed hydrogeochemical studies) is recommended for a good quality groundwater supply. This will prevent water-borne infections given the increasing urbanisation.

Water containing high concentrations of nitrate is unfit for human consumption and, if discharging to freshwater or marine habitats, can contribute to algal blooms and eutrophication. The level of nitrate contamination in groundwater of two densely populated, agro-industrial areas of the Cameroon Volcanic Line (CVL) (Banana Plain and Mount Cameroon area) was evaluated. A total of 100 samples from boreholes, open wells and springs (67 from the Banana Plain; 33 from springs only, in the Mount Cameroon area) were collected in April 2009 and January 2010 and analyzed for chemical constituents, including nitrates. The average groundwater nitrate concentrations for the studied areas are: 17.28 mg/l for the Banana Plain and 2.90 mg/l for the Mount Cameroon area. Overall, groundwaters are relatively free from excessive nitrate contamination, with nitrate concentrations in only 6 % of groundwater resources in the Banana Plain exceeding the maximum admissible concentration for drinking water (50 mg/l). Sources of NO3−in groundwater of this region may be mainly anthropogenic (N-fertilizers, sewerage, animal waste, organic manure, pit latrines, etc.). Multivariate statistical analyses of the hydrochemical data revealed that three factors were responsible for the groundwater chemistry (especially, degree of nitrate contamination): (1) a geogenic factor; (2) nitrate contamination factor; (3) ionic enrichment factor. The impact of anthropogenic activities, especially groundwater nitrate contamination, is more accentuated in the Banana Plain than in the Mount Cameroon area. This study also demonstrates the usefulness of multivariate statistical analysis in groundwater study as a supplementary tool for interpretation of complex hydrochemical data sets.

The Bamenda Highlands contains numerous dilute and soda springs of unknown hydrological provenance. These dilute springs are a vital source of drinking water to the inhabitants. As a contribution to water management, this study investigated the spring water recharge, residence time and sub-surface circulation using δ18O, δD, 3H, CFCs, SF6and TDS. A plot of both water types along the local meteoric water line indicated the meteoric origin and rapid recharge following precipitation. Dilute springs with a δ18O altitude effect of 0.27/100 m suggested recharge at different elevations. The CFC-12, CFC-11 and CFC-113 dating (complemented by 3H) showed reasonable young apparent ages of dilute springs ranging from 21 to > 52 (mean/median of 25) years and old soda springs (> 52 years). SF6concentrations in dilute springs revealed exceptionally young ages relative to CFCs modelled ages suggesting a terrigenous enrichment of the former. Thus, groundwater dating with SF6is unreliable in the area. Besides the old apparent ages of soda springs, their highly depleted δ18O and high TDS (mean of 1396 mg/l) indicated palaeo-recharge and high water–rock interaction, respectively. In contrast, the low TDS of dilute springs (< 140 mg/l) indicated low-water interaction. Most dilute springs showed exponential mixing models indicating heterogeneous recharge under unconfined aquifer conditions. Conversely, the old soda springs displayed piston flow and binary mixing models. The meteoric recharge and similar residence time of the shallow dilute springs suggested natural resilience to short-term changes in climatic conditions. Thus, low shallow groundwater abstraction is sustainable at the Bamenda Highlands.