Rainfall and land use impacts on water quality and communities in the Waimanu River Catchment in the South Pacific: the case of Viti Levu, Fiji

A community-based assessment along with a water quality framework was used to explore the Waimanu River water quality and to determine the impacts of the water quality on the communities which rely on the river for livelihood, sustenance, and recreation. Since both climatic and non-climatic factors affect the river system, the study used rainfall variability as well as land use assessments in addition to the community-based assessment to assess the effects of changing environmental factors on the river water quality. It was found that frequent rainfall intensified the runoff into the Waimanu River of contaminants arising from unsustainable land use practices in the Waimanu Catchment including agriculture, gravel extraction, logging, deforestation, and improper waste management. These led to physicochemical and microbial pollution in the river which augmented the vulnerability of the riverine communities to water pollution by hampering their food, water, income, and health securities. The river water quality is expected to further deteriorate as future climate change projections predict an intensification of annual rainfall events, thereby increasing river water contamination and risks to aquatic life and human life. Non-climatic factors that endanger water quality could be controlled by implementing better upstream land and waste management strategies on a catchment scale to minimize the adverse impacts of declining water quality on downstream communities. Methodologies employed in this study to monitor and maintain river water quality are applicable on a global scale to promote the health and security of riverine communities.