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Impacts of
Beaver Dam Removal
Hannah Behar and Emma Burgeson
M.S. students in Water Resources Science
University of Minnesota Duluth
Research Question: How do beaver dams impact
watershed hydrology?
1. Water source & storage
2. Discharge
3. Temperature
4. Temporal variation
The Knife River Watershed
https://www.pca.state.mn.us/sites/default/files/wq-iw10-01e.pdf
Forest Cover
https://www.pca.state.mn.us/sites/default/files/wq-iw10-01e.pdf
GAP Level 3 Acres Percentage Aquatic 69 0%
Aspen/White Birch 37944 69% Barren 95 0% Black Ash 652 1% Cropland 807 1% Developed 604 1% Grassland 2336 4% Lowland Black Spruce 115 0%
Lowland Northern White-Cedar
1371 2%
Lowland Shrub 5353 10% Maple/Basswood 1338 2% Marsh 20 0% Pine 619 1% Spruce/Fir 2541 5% Tamarack 387 1% Upland Cedar 261 0% Upland Conifer 14 0% Upland Shrub 831 2% Total 55359 100%
Forest Cover
https://www.pca.state.mn.us/sites/default/files/wq-iw10-01e.pdf
GAP Level 3 Acres Percentage Aquatic 69 0% Aspen/White Birch 37944 69% Barren 95 0% Black Ash 652 1% Cropland 807 1% Developed 604 1% Grassland 2336 4% Lowland Black Spruce 115 0%
Lowland Northern White-Cedar
1371 2%
Lowland Shrub 5353 10%
Maple/Basswood 1338 2% Marsh 20 0% Pine 619 1%
Spruce/Fir 2541 5% Tamarack 387 1% Upland Cedar 261 0% Upland Conifer 14 0% Upland Shrub 831 2% Total 55359 100%
Surficial Geology ● Highland Moraine
● Transitional area
● Superior Lobe Clay Plain
Gran 2016 hthttps://www.flickr.com/photos/jsjgeology/22162400130/in/photostream/
Surficial Geology ● Infiltration of < .05 inches / hour ● Recharge rate of 8.4 inches / year ● very low infiltration capacity → high
overland flow potential
Gran 2016 https://imnh.iri.isu.edu/digitalatlas/hydr/concepts/surfhyd/srfwtr.htm
Discharge ● Knife River is strongly
dependent on runoff to maintain flows
● Flashy response to precipitation events
http://stream1.cmatc.cn/pub/comet/HydrologyFlooding/hydrograph/comet/hydro/basic/UnitHydrograph/print_version/02-terminology.htm
Discharge ● Strongly dependent on
runoff to maintain flows
https://www.pca.state.mn.us/sites/default/files/wq-iw10-01e.pdf
Snow accumulates
Discharge ● Strongly dependent on
runoff to maintain flows
https://www.pca.state.mn.us/sites/default/files/wq-iw10-01e.pdf
April
Discharge ● Strongly dependent on
runoff to maintain flows
https://www.pca.state.mn.us/sites/default/files/wq-iw10-01e.pdf
August
Research Question: How do beaver dams impact watershed hydrology under low flow conditions?
https://content.ces.ncsu.edu/natural-stream-processes
Knife River Watershed
DNR estimates 0.6 beaver colonies / river mile across Minnesota
0.6 x 181 → potential for roughly 109 beaver colonies
(Bouwes et al. 2016)
Research Question: How do beaver dams impact
watershed hydrology?
1. Water source & storage
● Storage in ponds
● Infiltration and exchange
with groundwater
● Upwelling
https://www.researchgate.net/publication/319043632_To_What_Extent_Might_Beaver_Dam_Building_Buffer_Water_Storage_Losses_Associated_with_a_Declining_Snowpack/figures?lo=1
Research Question: How do beaver dams impact
watershed hydrology?
2. Discharge
● Impoundments may reduce
peak flows
● Seasonal variation
https://utahcbcp.org/ou-files/boxelder/BeaverPresentation_PortugalSept2015.pdf
Research Question: How do beaver dams impact
watershed hydrology?
3. Temperature
● Pond surface
● Deep water
● Below the dam
(Bouwes et al. 2016)
Project Sites
4 paired watersheds with similar characteristics
8 total sites
Combination of state and private land
Needed to have active beavers AND landowner permission
Project Sites
Sites 1 and 2 were chosen for their upland features
Headwaters
Lower relief
Hummocky morainal area
Project Sites
Sites 3 and 4 were lower in the stream
Greater relief
Flashier systems
In lake clay area
Project Sites
“B” sites will have beaver and dams both years
“T” sites will have beavers and dams the first year, but not the second
What Are We Doing and Why? ● Mapping beaver dams and ponds ● Measuring velocity and stage height of stream ● Collecting water samples ● Collecting temperature data ● Estimating evaporation
Summer 2018 1. Installed equipment
a. Stream gauges b. Shallow groundwater wells c. Air and water temperature loggers d. Evaporation pans
2. Water samples collected 3. Velocity measured 4. Rating curves created
Equipment Stream Gauge
Stage Height
Stream samples come from a riffle near the gauges at each site
Equipment Shallow Groundwater Well
Height of water table continuously recorded
Groundwater samples
Equipment Pressure Transducer
Records the pressure of water above the device
Mostly deployed in streams and wells
1 deployed to measure barometric pressure
Stable Isotope Samples and Analysis Stable isotopes 2H (deuterium) and 18O to help determine the source of water in the streams
Samples come from: ponds, streams, shallow wells, precipitation collectors, and deep groundwater wells from landowners
Chemical separation of baseflow
Temperature Analysis What do beaver ponds do to the temperature of water?
Fall 2018: Mapping Storage Capacity and Dam Characteristics Bathymetry + Surface Area = Volume of water in each pond
Moving Forward Data Crunching
Water samples will be analyzed for isotopic signatures
Discharge calculated
Temperature data
Treatment will resume in half of the sites in spring/summer of 2019
Outreach Undergraduate field days
Taking out family and friends
Speaking with landowners Future conferences
Any ideas? Let us know!
Project Collaborators
Dr. Karen Gran - Principal Investigator
Dr. Salli Dymond - Co - Investigator
Dr. Rebecca Teasley - Co- Investigator
Josh Dumke, M.S. - Co- Investigator and NRRI Fish Biologist
Deserae Hendrickson - Collaborator and MNDNR Duluth Area Fisheries Supervisor
Hannah Behar - WRS graduate student
Emma Burgeson - WRS graduate student
Nick Peterson - civil engineering graduate student
Craig Steiskal - field assistant
Lizzie Boor - field assistant
Lara Scott - WRS graduate student, field crew
Thank You