Thursday, March 1, 2007
Hydrologic effects of land cover and temperature change in the Puget Sound basin
Land cover has changed in the Puget Sound region since the first European settlement in the mid-19th Century. These changes have consisted largely of urban growth in the lowland areas, and removal of old growth timber and replacement with forests having a range of maturity over most of the upland area, along with construction of forest roads. We use the Distributed Hydrology-Soil-Vegetation Model (DHSVM) run over a 87-year period with current land cover, and reconstructed land cover representative of conditions early in the post-European settlement era, to assess the effects of land cover change on the magnitude of freshwater fluxes to Puget Sound. Reconstructed land cover is based on a survey map of forest density in Washington State published by the Department of Interior in 1883. To assess the effects of climate change over the period of the climate record (roughly 87 years) we used 3 temperature regimes. The first temperature regime is generated from adjusting the entire record to have temperatures similar to those of the most recent two decades, and the second temperature regime was generated from adjusting the entire record to have temperatures similar to those of the early instrumental record. The third temperature regime is the historical temperature without any adjustment. Through comparison of 87 years of hydrologic predictions for combinations of historic and current land cover and climate, we are able to assess their relative contributions to long-term changes in freshwater fluxes to Puget Sound. Other research partners in this project include Dennis P. Lettenmaier (UW Dept. of Civil and Environmental Engineering), Marina Alberti (UW Department of Urban Design and Planning), and Jeffrey E. Richey (UW School of Oceanography).
Lan Cuo is a post-doctoral researchers in the Land Surface Hydrology Research Group at the UW Department of Civil and Environmental Engineering.