Modeling Forest Management Strategies for Hydrological Climate Change Adaptation in the upper Columbia

Management of forest lands in the Upper Columbia River basin is necessary to ensure the sustainability of natural ecosystems and enhance protection and recovery of fish and wildlife populations. By 2030, summertime surface water demand is expected to significantly exceed supply in most years in many Upper Columbia tributaries; in some years, a portion of these tributaries will exceed supply even outside the summer months. Forest restoration (i.e., timber harvest, prescribed burning, thinning) reduces canopy cover and, subsequently, has been shown in many cases to increase snow accumulation and total runoff volume. We use the Distributed Hydrology Soil Vegetation Model (DHSVM) to predict hydrologic properties and changes associated with realistic forest restoration scenarios prescribed in high spatial detail (90 m) within snow-dominated watersheds of the upper Columbia under current and future climate conditions. We consider changes in hydrological processes related to snowpack, stream discharge, and water temperature. Model results suggest forest restoration will impact annual water yield under both current and future climate conditions and the impact of forest restoration on the timing of snowmelt and streamflow varies from year to year and is highly dependent on local meteorological conditions and particular forest restoration scenarios. Corresponding changes in water temperature will also be discussed.