Assessment of freshwater ecosystem services in the Tualatin and Yamhill basins under climate change and urbanization

We estimate and map the provision of freshwater ecosystem services (ES) for the Tualatin and Yamhill basins of northwestern Oregon under a series of urbanization and climate change scenarios centered on the year 2050 using the Integrated Valuation of Environmental Services and Tradeoffs (InVEST) modeling toolset. Results for the study area suggest that water yield estimates are highly sensitive to climate, especially in the lowlands, while nutrient export and retention estimates are overwhelmingly driven by land cover. Sediment exports and retention are projected to increase throughout the study area due to higher erosivity from increasing winter rainfall. When the ES estimates are summarized as bundles, the spatial patterns of the levels of ES provision are largely consistent regardless of climate and urbanization scenarios. InVEST has utility as a landscape planning tool, and the presented analysis supports a conclusion that restoration efforts in the Yamhill basin would have a greater effect than those in the Tualatin in improving water quality downstream. The estimated relative changes in ES provision under different climate and urbanization scenarios are valuable for land management decisions because they show potential tradeoffs between provisioning and regulating ES.