Title: 2016 SUSTAINING COLORADO WATERSHEDS CONFERENCE WORKSHOP SUMMARY:
BEAVER DAM ANALOGS (BDA)
Author: Gil Barth
Post Date: 3/13/2017
Every year I look forward to the Sustaining Colorado Watersheds Conference, and 2016 was no exception. For many years now I have enjoyed the spectacular settings, as well as opportunities to reconnect with colleagues, meet new people and expand my horizons. Last fall, however, I found one of the pre-conference workshops to be particularly inspiring. Dr. Sue Niezgoda presented a Beaver Dam Analog (BDA) workshop, providing an overview of these artificial constructs intended to mimic beaver-dam functionality and potentially entice beaver into adopting specific locations.
Sometimes a product sells itself: beaver are a “charismatic macro-scale fauna” (Wohl, personal communication, 2016). Sometimes salesperson enthusiasm sells the product: Dr. Niezgoda is an exciting presenter. Combining an outstanding product with animated and intelligent presentation results in a fantastic workshop and an audience full of converts and enthusiasts.
After having the opportunity to listen to her fascinating presentation, I came away with the following impression. Dr. Niezgoda’s central thesis is that beaver dams, or beaver dam analogs, are an effective and efficient mechanism for improving and preserving geomorphic conditions, water quantity, water quality, and habitat while at the same time providing opportunities to restore and expand resiliency in anticipation of potential climate change impacts. Dr. Niezgoda’s presentation provided an introduction, methods, results, and conclusions. In the short span of a few hours, I felt educated on the salient aspects and benefits, and attempt to summarize them for you in this blog.
The introduction consisted of a problem statement for motivation. Problems identified ranged from channel incision to water quality impairment. The introduction also provided an overview of the beaver and their effectiveness and versatility as a generalist species, historically impacting a huge range of North America. Following the background information, Dr. Niezgoda provided a comprehensive summary of the potential benefits associated with typical beaver dam-building activities, including increased water retention and base flows, decreased peak flows, habitat expansion, increased groundwater recharge, improved water quality, geomorphic alteration (e.g., decreasing erosion and reverting channel incision). The final component of the introduction was the concept of mimicking beaver activities through the implantation of BDAs.
Among many other benefits, the introduction alone provided me with a lucid demonstration of the term “biogeomorphic contributions.” With words, graphs, site photographs, and even pictures of the cute fuzzy beavers, Dr. Niezgoda introduced the concept in tangible terms.
The methods discussion drew on a variety of field sites and included brief overviews of analyses. The field sites demonstrated the potential for implementation, outlined the required level of effort (relatively small by stream restoration standards), and highlighted design alternatives, such as earthen versus cedar stakes to address nuances in site-specific objectives. The analysis included flow simulation and assessment of relevant forces including two-dimensional simulation of shear stresses. These efforts demonstrated opportunities to understand the key factors in proper BDA implementation, and to develop insights about the limitations of the approach.
Results presented by Dr. Niezgoda were remarkable. The BDAs provided a surrogate for the beaver’s efforts. BDAs, in stark contrast to typical extensive restoration efforts which may not provide a lasting solution, are simple and have the potential to provide long-term solutions through their considerable list of benefits.