Y-K Delta Flood Planning Hazard and Assessment
Much of Alaska lacks important geospatial datasets commonly used for planning, and communities and resource managers struggle to adequately plan for, and predict, flood events. Understanding the distribution and type of wetlands present in a community is an important component of floodplain management planning as wetlands provide ecosystem services such as slowing the speed of flood waters and water storage. The U.S. Fish and Wildlife Service’s National Wetlands Inventory is currently working to map almost 200 million acres of wetlands to understand the abundance and distribution of these resources, including communities in the Yukon-Kuskokwim Delta that experience coastal and riverine flooding.
The Alaska District along with USFWS, the Alaska Geospatial Council and the Alaska DCRA and utilized this new data to create wetland maps specific to the City of Bethel, Village of Aniak, and the Native Village of Napaimute. These maps highlight infrastructure, culturally important areas and natural features of each community in relation to the location and category of existing wetlands, with the goal of informing future development and floodplain management planning decisions. Coupled guidelines on how to use the National Wetlands Inventory geodatabase data, these maps enable communities to better incorporate wetland data into the foundation of important community decisions and serve as a blueprint for similar maps in other communities.
Ice Jam Workshop and Freeze-up Investigations
This effort utilized ice jam expertise from the USACE Cold Regions Research and Engineering Laboratory (CRREL) to train state and local practitioners on Alaska-specific ice jam issues. A 2-day virtual workshop was held in April of 2022 and covered general topics including an overview of ice formation and ice mechanics, ice jam terminology, mitigation techniques and ice jam database information, as well as technical topics such as River Ice Hydraulics and Ice Jam Stage Frequency. Workshop attendees and presenters included a mix of planners, engineers and maintenance and operational personnel from State and Federal agencies.
In 2023 the project team completed a review and summary of historical ice jams in Alaska using CRREL Ice Jam Database. The analysis included summarizing climate information coincident with the jams and statistical correlations with the goals to develop a relationship between hydrologic and climatic conditions prior to freeze-up jam formation. This could be used operationally in the future to identify time periods that favor the formation of freeze-up jams. This information will allow local partners to prepare in advance and monitor trouble spots on area rivers. CRRREL also worked with state and local partners to evaluate partner identified problem areas and provided ice jam stage estimates and mitigation recommendations in a technical report published in May 2023.