Potential Hydrologic Response to a Prescribed Fire on a Small Mountainous

Prescribed fire is often used to control invasive weeds, improve habitat, and deter wildfire. The Northwest Watershed Research Center plans to burn a heavily studied 26-ha watershed. This paper investigates the potential hydrological response to that prescribed fire. Changes in water repellency and infiltration capacity were assumed not to limit the low intensity snowmelt input to the basin. Percolation, subsurface flow and runoff during the first runoff season are influenced by the soil moisture deficit created by pre-burn vegetation conditions and will likely not be influenced greatly by the fire. A year of reduced evapotranspiration following the fire is necessary to reduce the soil moisture deficit and increase percolation beyond the root zone and subsurface flow to the stream. Results indicate significant changes in streamflow in this subsurface-flow-dominated watershed may not be observed until the second snowmelt season following the fire and could increase by 25%. These results are unlike watersheds dominated by overland flow and surface runoff where increased flows are more likely to occur during the first year following a fire