Integrated flood vulnerability assessment of villages in the Waimanu River Catchment in the South Pacific: the case of Viti Levu, Fiji

Abstract

This paper uses a holistic approach within a catchment scale, through the application of both climatic and non-climatic parameters, to analyze the impacts of river floods on the human security needs of rural riverine communities in the Waimanu Catchment situated in Nausori, Fiji. Consideration of both climatic and non-climatic factors is required since non-climatic factors could be controlled to build resilience against floods. The indicator-based flood vulnerability index methodology is applicable worldwide, but the indicators used in this study were specifically related to the Pacific Island context. In the context of fluvial flood vulnerability, effects of land management and climate change are not mutually exclusive of each other. Consequently, vulnerability assessments should consider the connection between people's actions and ecosystems for the entire catchment area since upstream land use practices influence flood vulnerabilities downstream. In our research, a community-based flood vulnerability index system in conjunction with rainfall variability and land use assessments was used to quantitatively and qualitatively analyze the flood vulnerability, and it was found that increased rainfall, poor agricultural practices, gravel extraction, and improper waste management predominantly increased the exposure and sensitivity of midstream and downstream communities to river floods by modifying river morphology. Midstream communities in the Waimanu Catchment were most vulnerable to river floods due to their very low adaptive capacity in terms of poor ecosystem health and lack of natural resources to cope with the subsequent impacts of floods, being most sensitive to changes in land use and land cover.

A Review of Village Ecosystem Vulnerability and Resilience: Implications for the Rocky Desertification Control

“…The flood leads to the reduction of arable land, the displacement of farmers, and food insecurity [ 70 ]. Unreasonable human activities, such as increased rainfall in the upper reaches of the river, poor agricultural practices and sand mining, will increase the exposure and sensitivity of villages in the middle and lower reaches of the river to river floods [ 71 ]. Meteorological disasters, such as flood and drought, are the driving factors for the formation of vulnerability of planting-dependent villages [ 24 ].…”

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

“…Initially, secondary data was reviewed from journal articles and government reports to identify the impacts of climate change, climate variability, and human activities on the river water quality as well as to detect the consequences of the water quality on the communities in the Waimanu Catchment. In order to gather both qualitative and quantitative data, four methods were employed: (1) a participatory community-based assessment from Begg et al (2021), (2) rainfall variability, (3) land use assessment, and (4) river water quality assessment. A participatory community-based assessment method provides opportunities for participants to reveal the social, economic, and environmental issues which they tend to face, and focus group discussions are the primary research tool used to conduct vulnerability assessments at local rural community levels (Van Aalst et al 2008;Fazey et al 2010).…”

“…Higher intensity of rainfall and flooding in PICs as a result of seasonal El Niño-Southern Oscillation (ENSO) events (BoM and CSIRO 2011) increases runoffs rich in nutrients and chemical fertilizers from agricultural land. Land management practices occurring upstream cause adverse downstream impacts on receiving waters and communities (Carpenter and Jones 2004;Begg et al 2021).…”

“…Navatuvula is the upstream community since there are no villages situated above it and Navuso is the downstream community located closest to the mouth of the river. Midstream communities (Sawani and Vuniniudrovu) are situated between the upper and downstream communities of the river (Begg et al 2021).…”

“…Observation of variations in river water quality is essential since rivers are very important for the sustainability of ecosystems and human communities residing along their banks while being sensitive to the impacts of climate change and climate variability (Emanuel et al 1985;Whitehead et al 2006;ADB and WAF 2016;Begg et al 2021). Rivers serve as a primary habitat source for freshwater organisms while humans have a direct dependence on freshwater for drinking, fishing, transportation, and recreational and industrial uses (Dudgeon et al 2006).…”