Why Beaver Dams?
Beavers (and their dams) are everywhere – from the northern parts of Mexico to the Canadian arctic; from 12,000ft up in the Rocky Mountains all the way down to the California and Oregon coasts.
Up until the last couple centuries, beavers had a greater environmental impact on the North American continent than humans did. They engineered vast networks of wetlands which served countless key hydrologic and ecologic functions in the landscape. Then European colonization and the fur trade decimated beaver populations – dams breached, wetlands dried up, flood waves crashed through the waterways unhindered, salmon habitat suffered, and the North American landscape was fundamentally changed.
Today, beaver populations are on the rise. As beavers return to their old stomping grounds – whether they’re in the desert or forest, coast or mountain, urban or wilderness – scientists and citizens alike are asking themselves, how will the landscape change? I am one of those scientists seeking to understand how the return of beaver will alter the future of water in a warming world.
Below you will find a summary of some of my recent ecohydrology research.
The Role of Beaver Damming in Maintaining Riparian Vegetation Health During Droughts (2015 – present)
There are several important hydrologic functions of beaver damming on a landscape, one of which is the ability to buffer nearby riparian vegetation against the effects of drought. Put simply, water stored in the beaver ponds can seep into the nearby soil where it is accessible to the roots of the riparian wetland vegetation when there is otherwise low water availability due to decreased precipitation and reduced/no streamflow. To understand and quantify the ability for beaver damming to buffer droughts, I use primarily remote sensing (Landsat satellite images) and modeling to estimate the health of vegetation around beaver ponds.
In August 2017, I submitted a case study for publication on the role beaver ponds along Susie and Maggie Creek, NV played in maintaining riparian vegetation health during seasonal and multiyear droughts. The paper has been accepted and will be published in Ecohydrology in 2018.
The next step in this project is to expand my study to more field sites, compare observed and modeled ET to water volumes stored in beaver ponds, and untangle the relationships between pond characteristics, damming intensity, total riparian biomass, and timescales of drought buffering.
The Role Beaver Dams Play in Groundwater-Surface Water Interactions in Arid and Semi-Arid Climates (2017 – present)
A key tool in moving from case studies to generalizable results is a physically based model for the hydrologic processes occurring in the shallow subsurface around and underneath beaver ponds in arid and semi-arid climates. I have developed a simple, generalizable model using the vadose zone modeling software HYDRUS 2D/3D. My model can help determine when, where, and under what conditions beaver damming leads to significant groundwater-surface water interaction – with special attention to the understanding how the variability in dam construction and repair impacts hydrologic processes at the dam-pond interface. This model will be a key step in understanding and predicting how beaver damming will influence water residence times, nutrient fluxes, water temperature, and other ecologically relevant characteristics of a given watershed.
Beavers: Ecosystem Engineers or Firefighters? (2018 – present)
Beaver damming raises the water table, saturates nearby soil, and ponds large volumes of surface water throughout the American west. Water – unsurprisingly – is very difficult to burn. So how do landscape-scale networks of beaver dams impact the size and spread of wildfires? I’m combining historical accounts of beaver wetlands acting as firebreaks, hydrologic modeling, fire spread modeling, and beaver occupancy modeling to start answering the question: are beavers just nature’s engineer, or are they firefighters too?