Adapting Locally to Sea-level Rise

By: Haunani Kane

Wetlands are important to Island communities because they provide food in the form of loʻi (taro patch), and loko iʻa (fishpond), trap sediment that may otherwise enter the ocean, and provide habitat to a number of native and endangered species.  Sea-level rise, however, threatens the integrity of coastal wetlands due to increased erosion, salt-water intrusion and flooding. The greatest challenge for wetland managers/users will be to prioritize management actions at each of the areas that are predicted to be impacted.  To assist in this challenge we worked closely with wetland users to develop two strategies to manage predicted impacts.

Firstly, due to the low gradient of most coastal plain environments, the rate of sea-level rise impact will rapidly accelerate once the height of the sea surface exceeds a critical elevation.  We calculate a local sea-level rise critical elevation (similar to a tipping point) that marks the end of a slow phase of flooding and the onset of rapid flooding.  The outcome of this method provides wetland managers with maps that can be used to create an inventory of resources that may be impacted during the slow and fast phases of flooding.

Secondly, within highly managed coastal areas, vulnerability is related to site the specific goals of coastal stakeholders.  For example in response to sea-level rise a kalo farmer may prioritize management efforts at the loʻi over the nearby pond because the loʻi provides food for his/her ʻohana (family). On the other hand, a federal manager who is tasked with providing habitat for endangered species will focus sea-level rise management efforts on the pond because it is used more frequently by endangered waterbirds.  We worked closely with wetland users to develop a ranking system that models the local vulnerability as a function of 6 input parameters: type of inundation, time of inundation, habitat value, soil type, infrastructure, and coastal erosion.  Through the use of an in person survey each input parameter was ranked based upon the goals and objectives the users of that area.  Areas of the highest cumulative vulnerability were mapped and should be used to prioritize future adaptive management.

Haunani Kane is a graduate student in Geology and Geophysics, working in the Coastal Geology lab of Dr. Chip Fletcher within SOEST. Haunani is from Kailua, O‘ahu, and her research centers on better understanding past and future sea-level rise events to assist coastal risk management. She believes that by tying culture to science we may be able to inspire more young native scientists.