| Popis: |
Beaver ponds require a supply of water, which ultimately comes from precipitation. Although most of northern Minnesota’s precipitation is received in the summer months, snowmelt is the main driver of peak streamflow in the spring. I analyzed NOAA snowpack records and USGS streamflow records to show that peak annual streamflow was significantly related to maximum snow water equivalent during the winters of 2005–2016. We conducted intensive field studies of water fluxes in a Kabetogama Peninsula beaver meadow, measuring evapotranspiration, pond level, groundwater, streamflow, and runoff from watershed side slopes. Evapotranspiration was a significant source of water loss from the beaver meadow during late summer, with discernable diurnal effects on streamflow, water table, and pond level. Groundwater measurements showed recharge (i.e., water flowing from the surface into the ground) occurring within most of the beaver meadow, but periodic discharge (i.e., water flowing from the ground toward the surface) in sites closer to the stream flowing through the beaver meadow. “Edge collectors” positioned around the perimeter of the beaver meadow showed that lateral fluxes of runoff into the beaver meadow were spatially variable, such that the temporal pattern of flow in a gently sloping portion of the catchment with >0.3 m of soil was different than that for three sites with steeper slopes and shallower soils over bedrock. A spatially explicit model that routed flow within the beaver meadow catchment successfully replicated this difference. |
