Strengthening rural community water safety planning in Pacific Island countries: evidence and lessons from Solomon Islands, Vanuatu, and Fiji.

Pacific Island Countries (PICs) collectively have the lowest rates of access to safely managed or basic drinking water and sanitation globally. They are also the least urbanised, have dynamic socioeconomic and increasing climate-linked challenges. Community-based water managers need to respond to variability in water availability and quality caused by a range of hazards. Water Safety Planning (WSP), a widely adopted approach to assessing water supply, offers a risk-based approach to mitigating both existing and future hazards. WSP is adaptable, and making modifications to prescribed WSP to adapt it to the local context is common practice. Within the Pacific Community Water Management Plus research project, we used formative research and co-development processes to understand existing local modifications, whether further modifications are required, and, to develop additional modifications to WSP in Fiji, Vanuatu and Solomon Islands. The types of additional local modifications we recommend reflect the unique context of PICs, including adjusting for community management of water supplies and required collective action, community governance systems, levels of social cohesion in communities, and preferred adult-learning pedagogies. Incorporating modifications that address these factors into future WSP will improve the likelihood of sustained and safe community water services in Pacific and similar contexts.

Management of saltwater intrusion using 3D numerical modelling: a first for Pacific Island country of Vanuatu.

Small island countries like Vanuatu are facing the brunt of climate change, sea level rise (SLR), tropical cyclones, and limited or declining access to freshwater. The Tagabe coastal aquifer in Port Vila (the capital of Vanuatu) shows the presence of salinity, indicating saltwater intrusion (SWI). This study aims to develop and evaluate effective SWI management strategies for Tagabe coastal aquifer. To manage SWI, the numerical simulation model for the study area was developed using the SEAWAT code. The flow model was developed using MODFLOW and the transport model was developed using MT3DMS. Whereby SEAWAT solved flow and transport equations simultaneously. The model was calibrated, and different scenarios were evaluated for the management of SWI. The SLR was also considered in the model simulations. The results indicated that increased population, pumping rates, and SLR affect the SWI rates. To manage the SWI, we introduced hydraulic barriers like barrier wells and injection wells which effectively managed SWI in Tagabe coastal aquifer. The results from this study are significantly important whereby, the water managers, site owners, and governing bodies can use the management strategies presented in this study to create policies and regulations for managing SWI rates in Port Vila. Additionally, the water industry, private businesses, and investors who wish to extract groundwater from the Tagabe can use this study as a reference for daily or yearly freshwater production rates without the risk of SWI.

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.

Assessment of biodegradable chelating agents in the phytoextraction of heavy metals from multi-metal contaminated soil.

A pot incubation experiment under natural conditions was designed to investigate the effects of three biodegradable chelating agents, namely; the [S,S]-isomer of ethylenediamine disuccinate (EDDS), citric acid (CA), and tetrasodium N,N-Bis(carboxymethyl)-L-glutamate acid (GLDA), on two plant species (Brassica juncea and Brassica rapa) in terms of plant foliar growth, dry matter yield, and heavy metal (HM) accumulation. Both plant species exhibited diminished growth and symptoms of phytotoxicity under HM stress. The application of EDDS and CA affected plant foliar growth, biomass production, and led to the development of chlorotic lesions on leaves. EDDS and CA also decreased the shoot length by 38.5% and 45.2% in B. juncea, and 60.1% and 100% in B. rapa, respectively. In contrast, GLDA relieved HM stress by significantly increasing plant growth (P > 0.05) and was shown to be well tolerated (tolerance index [TI]; B. juncea = 99% and B. rapa = 123%). Among both plants, B. juncea displayed the ability to accumulate a wider range of HMs at higher concentrations. Amongst the three chelators, EDDS induced the highest bioconcentration (BCF) of Pb (2.45), Zn (2.68), and Cd (3.36) while CA achieved better results for Ni (4.01) and Cr (1.45). However, the current results showed that even with the application of chelating agents, HMs were predominantly accumulated in roots and translocation factor was generally <1. The findings of this investigation emphasize that chelate-assisted phytoextraction with Brassica spp. is highly limited in multi-metal settings, making it an unsuitable option for severely contaminated sites.

Baseline assessment of coastal water quality, in Vanuatu, South Pacific: Insights gained from in-situ sampling.

Nearshore deterioration of water quality in Pacific coastal waters is a growing problem, associated with increasing urban and industrial sewage discharges, and agricultural runoff. Published water quality studies in the Pacific region are limited in both number and scope, making it difficult to resolve the extent of the issue or quantify the variability of water quality across Pacific islands and countries. This study collected water quality measurements over three years in the coastal waters around the Island of Efate (Vanuatu) with majority of work carried out in Port Vila, its capital. Port Vila is the key urban centre for Vanuatu where the increasing population and pollution inputs are placing substantial pressure on the coastal environment. Highest concentrations of dissolved nutrients and suspended sediments were measured adjacent or near the urban drains that enter the coastal areas along the capital's seafront, highlighting many of the issues around anthropogenic inputs are linked to the increasing urbanisation in Port Vila Bay. We provide baseline data that explores variability of coastal water quality and these types of datasets for Pacific islands are a first step towards facilitating development of long-term monitoring programmes and informing coastal zone management decision making.

Faecal contamination of groundwater in rural Vanuatu: prevalence and predictors.

Groundwater is an important source of water for coastal communities in Pacific Island Countries. This study assessed the prevalence and predictors of faecal contamination in groundwater sources across 11 islands in Vanuatu. Escherichia coli was detected in 49% of sources and E. coli concentration exceeded 10 MPN (most probable number)/100 mL for 23% of sources. When adjusting for other variables, the detection of E. coli was significantly associated with severe pump stand corrosion, suggestive of contaminated run-off directly entering boreholes. E. coli concentration >10 MPN/100 mL was also significantly associated with: (i) hand-dug wells (as compared to drilled boreholes); (ii) severe pump stand corrosion; (iii) water points underlain by volcanic rocks (as compared to coral limestone); and (iv) rainfall in the previous 24 h. Encasing pump stands in concrete - as some communities had done - was found to have a significant protective effect. While baseline statistics for Sustainable Development Goal target 6.1 suggest that 87% of Vanuatu's rural population have access to at least a basic (improved) water source, the results from this study point to extensive microbial water quality concerns linked to degraded water supply infrastructure in need of rehabilitation.