The Role of Porosity on the Efficacy of Beaver Dam Analogs
Faculty Mentor
Camille McNeely
Document Type
Poster
Start Date
10-5-2023 11:15 AM
End Date
10-5-2023 1:00 PM
Location
PUB NCR
Department
Biology
Abstract
In the Western United States, climate change-caused mega-fires are increasing in frequency and severity, leaving many watersheds vulnerable to erosion and flooding. Studies show that beaver-engineered ecosystems are integral to the resiliency of freshwater systems by creating impoundments and wetlands that mitigate flooding and raise water tables. While beaver dams have well-documented benefits for water quality, many streams lack the habitat to sustain beaver populations. Thus, despite limited research, manufactured structures designed to mimic the hydraulic functions of natural beaver dams, known as Beaver Dam Analogs (BDAs), have become a popular tool in stream restoration.
In this study, I assess the effectiveness of BDAs installed by multiple agencies across Washington State. I am comparing the BDA's ability to slow and store water by measuring water storage and dam porosity across six BDA restoration reaches, six paired control reaches, and four beaver dam reaches. Preliminary data from the Methow and Okanogan watersheds demonstrate that beaver dams substantially affect water storage. Beaver reaches have dramatically slower water travel times (7x to >400x) compared to control and restoration reaches (p < 0.05). BDA and natural beaver dam complexes also have substantial surface water volume differences (250x).
While natural beaver dams are porous structures, the higher porosity of BDAs may contribute to less water storage compared to beaver-built dams. Porosity may decrease over time if stream-carried sediment fills gaps in BDA structures. However, this requires sediment-rich streams and high-flow events; therefore, porosity is likely a critical factor in BDA effectiveness.
Recommended Citation
Nagle, Sawyer, "The Role of Porosity on the Efficacy of Beaver Dam Analogs" (2023). 2023 Symposium. 50.
https://dc.ewu.edu/srcw_2023/res_2023/p2_2023/50
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
The Role of Porosity on the Efficacy of Beaver Dam Analogs
PUB NCR
In the Western United States, climate change-caused mega-fires are increasing in frequency and severity, leaving many watersheds vulnerable to erosion and flooding. Studies show that beaver-engineered ecosystems are integral to the resiliency of freshwater systems by creating impoundments and wetlands that mitigate flooding and raise water tables. While beaver dams have well-documented benefits for water quality, many streams lack the habitat to sustain beaver populations. Thus, despite limited research, manufactured structures designed to mimic the hydraulic functions of natural beaver dams, known as Beaver Dam Analogs (BDAs), have become a popular tool in stream restoration.
In this study, I assess the effectiveness of BDAs installed by multiple agencies across Washington State. I am comparing the BDA's ability to slow and store water by measuring water storage and dam porosity across six BDA restoration reaches, six paired control reaches, and four beaver dam reaches. Preliminary data from the Methow and Okanogan watersheds demonstrate that beaver dams substantially affect water storage. Beaver reaches have dramatically slower water travel times (7x to >400x) compared to control and restoration reaches (p < 0.05). BDA and natural beaver dam complexes also have substantial surface water volume differences (250x).
While natural beaver dams are porous structures, the higher porosity of BDAs may contribute to less water storage compared to beaver-built dams. Porosity may decrease over time if stream-carried sediment fills gaps in BDA structures. However, this requires sediment-rich streams and high-flow events; therefore, porosity is likely a critical factor in BDA effectiveness.
