Water circulation and impact on water quality in the southwest of Efate Island, Vanuatu

In Small Island Developing States (SIDS), water pollution is not monitored or assessed frequently enough to fully understand the processes, impacts of water quality issues and what solutions are available This study investigated flushing time in Erakor lagoon and Port Vila Bay, Vanuatu using a numerical model developed in Delft3D. Microbial contamination by Escherichia coli was detected in multiple locations in the lagoon system with counts exceeding thresholds related to human health concerns. Modelling demonstrated a poor flushing time overall with a further decrease as the influence of waves and wind increased, especially in Vila Bay. Sea level rise resulted in an increase in flushing time downstream of the lagoon near the open sea, while with a decrease upstream and in Vila Bay. Based on these results, we recommend long-term continuous monitoring and identification of higher risks areas to prioritise decisions around wastewater management

Contending With Water Shortages in the Pacific: Performance of Private Rainwater Tanks Versus Communal Rainwater Tanks in Rural Vanuatu

Around 2 million people in the Pacific depend on rainwater collection for their drinking water, however these systems often struggle to provide sufficient quantities of water year round. This study examined the performance of 1,878 rainwater tanks across 19 islands in Vanuatu to assess whether the likelihood of a sufficient year-round supply of drinking water differed between village-level rainwater tanks used communally and private rainwater tanks owned by individual households (i.e., self-supply). More than half of the tanks assessed failed to provide a sufficient supply of water year round. Compared with communal rainwater tanks, private rainwater tanks had significantly higher odds of a sufficient year-round supply of water (adjusted odds ratio 1.61, 95% confidence interval 1.24–2.09, p < 0.001). This relationship was evident when adjusting for village-level clustering, year of installation, presence of other improved water sources, tank volume, number of users, and a proxy indicator for rainfall. Private rainwater tanks outperformed communal rainwater tanks irrespective of whether communal tanks were managed by a community-based committee. The findings support the notion that in some circumstances private property rights can help avert resource depletion, and that household self-supply is capable of delivering a more reliable water supply than community-based management. However, the study design was unable to rule out differences in roof catchment area as a factor influencing the results. Further work is needed to confirm and elucidate the mechanisms by which private ownership facilitates a year-round supply and understand the wider advantages and disadvantages of self-supply