Coastal bluffs have long been sought after for development of residential properties and other infrastructure, including those globally and along coastlines in the western U.S. However, rising sea levels are expected to cause an increase in coastal erosion, making these properties increasingly vulnerable. In Puget Sound, almost 70% of the coastline is heavily developed and more than 40% consists of bluffs, where increasing erosion is a concern for infrastructure loss and human safety. 

While bluff erosion can threaten coastal property, it plays an important role in coastal ecosystems and for the people that rely on them. Bluffs and bluff erosion are a major source of sediment to the region’s beaches and are also important to many commercially and culturally important fisheries, including for the region’s Tribes and First Nations. This is because intertidal species, such as butter clams and forage fish, rely on sufficient beach sediment to sustain their habitat and spawning grounds and are sensitive to changes that may result from rising sea levels and possible increased erosion. Only a few bluff recession studies have been completed in the Puget Sound, which have limitations due to sparse data characterizing bluff geology and erodibility. Because of the complicated relationship between human infrastructure and the health of coastal ecosystems, there is a need for continued research to refine and expand on existing bluff erosion studies to improve assessments of future coastal change.

To help meet this research need, Keeley will collaborate with the Tulalip Tribes’ Natural Resource Department (Tulalip), the United States Geological Survey (USGS), and Western Washington University to refine existing models of bluff erosion along the Tulalip Tribes Reservation shoreline on the Washington coast. She will explore how bluff geology and erodibility influences bluff erosion by compiling, testing, and collecting geotechnical data on the glacial sediment that comprises Puget Sound bluffs. Keeley will incorporate new bluff data generated from these efforts into existing models to project possible bluff positions and bluff sediment contributions to adjacent shorelines with sea level rise. 

This work is a component of a larger habitat suitability project with Tulalip and USGS, which aims to provide the information needed by Tulalip to ensure healthy intertidal ecosystems important to Tribal First Foods. The bluff change projections and bluff erodibility data generated from Keeley’s research will provide Tulalip and USGS with essential data to inform vulnerability assessments of bluff, beach and habitat changes for this larger project. These data will also be used to evaluate nature-based adaptation strategies for balancing shore protection and ecosystem productivity, including offshore oyster reefs, clam gardens, large woody debris, hanging aquaculture, as well as traditional grey infrastructure like seawalls. 

Keeley anticipates the data generated from this project will aid Tulalips’ decision-making for climate adaptation strategies and future development and that it may also be useful for other coastal land and resource managers. The methodology that is developed through her research will be easily adapted for use by other Tribes and coastal scientists in the region to protect culturally and ecologically significant species and habitats.