Samoan Islands are prone to climatic hazards that will likely increase in coming decades, affecting coastal communities and infrastructure around the islands. Climate models do not predict a reduction of such disaster events in the future in Samoa; indeed, most predict an increase in such events. Future rainfall in Samoa is uncertain as model results have been inconsistent; however, projections generally suggest that the dry season rainfall will decrease but the wet season rainfall will increase, which may lead to seasonal cycles of too much and too little water (ICCAI, 2011). Thus, the dry season will likely be drier and the wet season wetter (World Bank, 2010). The sea level in Samoa has been rising at 4 mm per year since 1983, which is slightly greater than the global average of 2.8-3.6 mm per year (ICCAI, 2011). Rising seas may compound problems either by resulting in a higher base and therefore increasing the height of storm surges, or by acting as a higher seaward barrier that restricts the escape of flood waters caused by excessive runoff (Walsh et al., 2004). Apart from coastal flooding, sea level rise (SLR) may accelerate the erosion of coastal margins, threatening surrounding land, property and infrastructure. Therefore, storm surge and flooding as well as wind damage that occurs during tropical cyclones can be seen as the principal hazards on the Samoan Islands.
As a part of the initiative of USAID Adapt Asia-Pacific in partnership with UNDP to support the Government of Samoa in addressing a range of climate hazard-related issues, the goal of this report is to identify key infrastructure and their functions and status in order to provide an overall picture of relative vulnerability to climate-related stresses of such infrastructure on the island. This report also aims to identify feasible adaptation measures based on consultations with the Government of Samoa and review its implementation plan for an economy-wide integration of climate change adaptation to reduce vulnerability in communities. A case study for the economic costs and benefits for an early warning system are also summarized. In this report, only water supply, sewerage, land transportation and power supply are considered for vulnerability assessment due to climate-related hazards. A detailed and exhaustive assessment of the climate-related vulnerability of the whole infrastructure system of Samoa will require detailed hazard mapping (e.g. flood hazard mapping, coastal erosion hazard mapping, etc.), the development of an inventory of critical infrastructure and their users, and finally, superimposing of the hazard maps with the inventory of the existing infrastructure. Such an exhaustive exercise is beyond the scope of this report due to the limited time available for this study as well as the lack of readily available data.