About
The Bonriki Inundation Vulnerability Assessment (BIVA) project is part of the Australian Government’s Pacific–Australia Climate Change Science and Adaptation Planning Program, within the International Climate Change Adaptation Initiative. The BIVA project was developed by the Geoscience Division of the Secretariat of the Pacific Community in partnership with the Australian Government and the Government of the Republic of Kiribati. The project was undertaken over 22 months, from May 2013 to February 2015.
The BIVA project focused on Kiribati’s National Water Reserve in Bonriki, South Tarawa, which is Bonriki’s source of raw, fresh water. The project comprised three interlinked components: stakeholder engagement, groundwater investigations and analysis, and coastal investigations and analysis. It aimed to improve our understanding of the vulnerability of the Bonriki Water Reserve to coastal hazards, and climate variability and change. Improving our knowledge of risks to this freshwater resource will enable better adaptation planning by the government.
Key Outcomes
The inundation and groundwater modelling has demonstrated that, although inundation of the Bonriki Water Reserve in an extreme event will significantly impact the lens, the probability of this extreme event occurring is relatively low (based on a 50-year intermediate–high climate change scenario and an extreme event with a 1% chance of occurring in any one year). The majority of modelled inundation events tend to be localised and confined to the coastal fringe, and the lens should recover after 2–5 years, depending on rainfall. The analysis has also shown that, although an extreme inundation event will impact the lens, threats from over-abstraction and low rainfall recharge are far more critical influences on its condition. However, the models did not consider morphological responses of the coast to climate change, climate variability and human activity over time, and the risk of inundation may increase in the future if coastal zone management plans are not implemented to ensure resilient shorelines.
The project has investigated the economic costs and benefits of potential management options in the event that the groundwater resource is too saline for distribution. The economic analysis considered using either desalination or large-scale rainwater harvesting to augment the Bonriki groundwater supply. In all scenarios modelled, desalination is the cheapest suitable option for backing up the Bonriki supply, while groundwater remains the cheapest source of water overall.
