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Predicting effects of environmental change on river inflows to Tillamook Bay, Oregon
Marois, D., Ted DeWitt, Bob Mckane, C. Brown, AND Pat Clinton. Predicting effects of environmental change on river inflows to Tillamook Bay, Oregon. American Water Resources Association Spring Specialty Conference, Snowbird, Utah, April 30 - May 03, 2017.
The topic of this conference is aquatic system connectivity. The research we are presenting at this conference shows how this connectivity can be simulated with models for estuarine rivers. This research demonstrates how ecohydrology models can be used to aid in predicting the effects of environmental change on estuarine river water quality and its associated ecosystem services. This abstract contributes to SHC 2.61.3.
Estuarine river watersheds provide valued ecosystem services to their surrounding communities including drinking water, fish habitat, and regulation of estuarine water quality. However, the provisioning of these services can be affected by changes in the quantity and quality of river water, such as those caused by altered landscapes or shifting temperatures or precipitation. We used the ecohydrology model, VELMA, in the Trask River watershed to simulate the effects of environmental change scenarios on estuarine river inputs to Tillamook Bay (OR) estuary. The Trask River watershed is 453 km2 and contains extensive agriculture, silviculture, urban, and wetland areas. VELMA was parameterized using existing spatial datasets of elevation, soil type, land use, air temperature, precipitation, river flow, and water quality. Simulated land use change scenarios included alterations in the distribution of the nitrogen-fixing tree species Alnus rubra, and comparisons of varying timber harvest plans. Scenarios involving spatial and temporal shifts in air temperature and precipitation trends were also simulated. Our research demonstrates the utility of ecohydrology models such as VELMA to aid in watershed management decision-making. Model outputs of river water flow, temperature, and nutrient concentrations can be used to predict effects on drinking water quality, salmonid populations, and estuarine water quality. This modeling effort is part of a larger framework of connected models being developed to simulate the networked hydrology and ecology of the estuary, the coastal waters, and the estuarine watershed. This framework aims to provide a more complete model of the many factors influencing estuarine ecosystem functions and the services they provide to their associated communities.