Climate risk assessments and management options for redevelopment of the Parliamentary Complex in Samoa, South Pacific

Abstract

The site of the Samoan Parliament Complex Redevelopment Project is in a coastal environment hazard zone as a result of high risk of several hazards, including damaging winds and flooding due to stormtides. This paper presents the findings of detailed hazard, vulnerability, exposure and adaptation assessments, and prioritises risk reduction measures based on the findings of cost benefit analyses, as well as other considerations.As a result of higher intensity rainfall events in the future, as well as a general increase in sea level, the frequency and depth of localised flooding of the site during periods of heavy rainfall are expected to increase. No significant change is anticipated in the exposure of the buildings to extreme wind gusts between present day and 2045–2055, but projected increases in the frequency of extreme high temperatures have relatively high certainty and are substantial. Inundation as a result of a cyclone-related stormtides is the highest risk for the site. By 2065, 50- and100-year stormtides could be 3.0 m and 3.2 m above mean sea level, respectively, compared to 2.6 m and 3.0 m for the same events in 1990. Water velocities experienced during such stormtides are projected to increase from 1.5ms−1 (in 1990) to 1.9ms−1 by 2055.Relocating the Parliamentary Complex would alleviate all of the key risks that were identified. However, for cultural and historic reasons this response was not favoured by the Government of Samoa. Two key ways to manage the identified risk of damaging stormtides were assessed, namely to increase the height of building platforms above the business as usual case of meeting the design code in force at the time (i.e. finished floor level at 2.8 m above mean sea level), or to increase protection of the entire site by raising the heights of the surrounding sea wall and embankments. Cost benefit analyses showed that raising finished floor levels was the much more cost-effective option for protecting the new buildings from damage due to stormtides.The new Parliamentary Chamber was officially opened in March 2019. Its climate resilient design reflects the findings of the above assessments, including the prioritised risk reduction measures. Keywords: Risk assessments, Vulnerability, Adaptation, Cost-benefit, Infrastructure, Samoa