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Developing Long-Term Records of Sea Level Fluctuations and Barrier Beach Evolution to Enhance Understanding of Ongoing and Future Coastal Change

Investigator

Christopher Maio Christopher MaioGeoscience Department
University of Alaska Fairbanks

Student

Synopsis

Supporting some of the largest salmon runs, as well as globally important migratory bird populations, southwestern Alaska’s coastal systems are some of the most ecologically productive in the North Pacific. These areas and the Alaska Natives who depend on them are highly vulnerable to accelerated rates of sea-level rise associated with ongoing climate change. Despite its vulnerability, the region remains largely understudied due to the enormous challenges of conducting research in this very remote region. The lack of knowledge regarding past fluctuations in sea levels and coastal landform evolution limits our understanding of future changes, hampering adaptation and mitigation strategies. During the past decade, there have been dramatic advances in the development of paleo-proxy data acquired through the use of sediment cores and trenching. These studies have illuminated centurial to millennial scale patterns in sea levels and helped decipher the driving forces behind the evolution of coastal landforms. The research will develop two paleo-climatic data sets that are important toward understanding the coastal response to climate change. These include (1) a 700–1000 year relative sea level record based on marine limiting plant macrofossil assemblages, and (2) an evolutionary model of the Goodnews Bay barrier complex based on beach ridge age, geometry, topographical surveys, and historical geospatial data sets. Additionally, the production of a digital elevation model will assist with the identification of coastal hazard zones. Sediment cores and trenching, coupled with ground-penetrating radar, macrofossil, isotopic, geospatial, and radiocarbon analysis, will provide the necessary information to achieve the stated objectives. In addition to research, a community-based hands-on coastal education program that integrates project results, cultural knowledge, and general concepts in coastal geomorphology will be carried out. Outreach will include two general education workshops held in Goodnews, a Goodnews high school coastal education project, the publication of a fact sheet, and participation in a regional stakeholder conference. These programs will inform and engage local residents, and by increasing environmental literacy will encourage informed decisions regarding coastal management strategies.

For project news, please see the 2016 news story “Shoreline monitoring in Goodnews Bay, Alaska, will help residents map changes.”

Overview

The issue

During the past century, average temperatures in Alaska have increased by 3.4°C in summer and as much as 6.3°C in winter. This rate is twice the national average over the same period and is predicted to further increase by as much as 7°C by 2100. Increased rates of sea level rise, coupled with rapid permafrost melt and an absence of landfast ice, are driving coastal erosion at historically unprecedented rates. Coastal erosion and marine inundation of freshwater environments in response to sea level rise is threatening the resiliency of Alaska’s coastline and is having broad implications for the sustainability of Alaska Native subsistence-based cultures and economies.

Why is this an Alaska Sea Grant project?

The research is ideally suited as an Alaska Sea Grant project for three primary reasons: (1) the development of new data sets regarding the interactions between sea levels and barrier systems will enable coastal residents to integrate science and traditional knowledge to better understand the implications of ongoing and future environmental change, (2) the development of local tidal datums and high resolution digital elevation model by Goodnews residents will provide leadership training for youth in natural science and be a direct link to higher education opportunities at the University of Alaska Fairbanks, and (3) coastal education programs will increase environmental literacy regarding coastal dynamics over multiple spatial and temporal scales, improving the local capability to understand and appropriately respond to climate-driven change.

Research collaborators

Woods Hole Oceanographic Institution, Coastal Systems Group
Alaska Pacific University, Fisheries, Aquatic Science and Technology Lab
Alaska Geographic Alliance
Alaska Geological and Geophysical Surveys

Results

What researchers learned

The Goodnews Bay coastal resiliency project has come to conclusion with many positive scientific, educational outreach, and management impacts. Since the project began in February 2015, we have increased the scientific understanding of the coastal geologic evolution of Goodnews Bay, created digital topographic maps and datasets spanning multiple spatiotemporal scales, and carried out a geospatial assessment of historical and modern erosion and flooding hazards. We have also been afforded a unique opportunity to build a long-term mutually beneficial relationship with the Native Village of Goodnews Bay, interacting with the community through a number of engaging research and education activities.

The eight-month extension on the project afforded us the additional time needed to carry out another field work season and complete data analysis and interpretation. Sea Grant Fellow, Rich Buzard, whose MS thesis has focused on the Goodnews shoreline change analysis, acquired an $8,117 UAF Global Change Student Research Grant funded by the Cooperative Institute for Arctic Research, which greatly improved our ability to leverage Sea Grant funds and carry out the additional research and education activities in 2017. The extension also allowed us to expand our shoreline change analysis to include the southern barrier and Village of Platinum. Undergraduate student Reyce Bogardus developed a baseline dataset of aerial imagery for the area surrounding Platinum and applied it to mapping general trends in erosion and accretion.

The final field work campaign was carried out during August 2017. During our visit, we were able to maintain and repair coastal monitoring sites for the community, and carry out a topographic survey. We used real-time kinematic GPS (GPS) to collect repeated coastal profile measurements and over 150 ground control points for an unmanned aerial vehicle (UAV) survey. This field work allowed us to produce a high resolution (16 cm) digital surface model (DSM) and an orthometrically corrected image mosaic (8 cm) of the community. In addition to these geospatial products, we have acquired the final dataset needed for Rich’s MS thesis and a peer-reviewed publication currently in preparation.

During our work in Goodnews Bay, we held the final community meeting to share the project’s results, discuss the findings with residents, and plan future collaborations. The event was held in the Rocky Mountain School and was very successful with over 40 participants. The event was made possible through direct support of the schools principle, Sally Benedict, and several middle and high school teachers. As part of the presentation, we discussed some of the challenges facing the community in regards to areas of the village vulnerable to future erosion and storm surge. We also discussed the overall resiliency of the community to mitigate and/or adapt to these identified vulnerabilities.

The research results and established community relationships are now serving as leverage for new proposals aimed at acquiring additional funding that builds on these initial accomplishments. The combined efforts have provided critical information for the assessment of the coastal resiliency of Goodnews Bay, and archived a high-resolution coastal topographic dataset in which to compare ongoing shoreline changes and accurately assess risks to future climate-driven perturbations. The work has also led to numerous impacts including the mentoring of undergraduate and graduate students, the publication, presentation, and visualization of results, increased awareness through articles disseminated through media outlets, and increased capacity to forecast storm surge in the village.

Research impacts

Alaska Sea Grant researchers involve residents in determining erosion rates and storm risk in a coastal Alaska community

Relevance: Despite the need for information for planning in a changing environment, Alaska’s 34,000 miles of shoreline are inconsistently monitored and under-instrumented for coastal erosion even in populated areas. Alaskans have knowledge, motivation, and ability to help quantify rates of erosion in remote areas. Storm events have raised awareness among residents and scientists that more data are needed on present and past sea levels, tides, and coast position.

Response: Alaska Sea Grant scientists used GPS to map the exact position of the coastline of the Native community of Goodnews Bay on the Bering Sea. They took 40 sediment cores in saltwater marshes to get a 1,000 year historical record of sea level fluctuations. They collected surface samples in the marsh to characterize elevation, vegetation type, salinity, and fossils. Enlisting the help of local students, they surveyed bluffs with ground penetrating radar to make a topographic map. Researchers asked Elders about changes they have noticed in the past, including the former village site, facilitated by the tribal council.

Results: Researchers have begun to determine erosion rates and identify coastal hazard zones in Goodnews Bay on the Bering Sea. The coastline fronting the village experienced shoreline retreat at 0-1 meter per year between 1957 and 2005. Some regions experienced 30-40 meters of horizontal land loss. Village infrastructure that could be at risk of flooding and erosion include the diesel power station, sewage treatment ponds, airport runway, and several homes. The half-mile of mud in front of the village, deposited in the last 50 years, is a natural seawall.

Recap: Alaska Sea Grant-funded researchers collaborated with local volunteers in Goodnews Bay to begin to map out rates of erosion and land loss in the past 50 years, and identify coastal hazard zones.