Doctoral Dissertation Research: Multi-Spatial Forecasts of Hydrologic Sensitivity to Climatic Change in the Pacific Northwest: A Process-Based Modeling Approach

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

Summer streamflow in the Pacific Northwest provides water for aquatic biota, agriculture, hydroelectric generation, recreation, and urban use. Water resources in the region are already limited and are expected to become more so in coming decades. Higher air temperatures associated with climatic change likely will lead to reduced snow accumulation and snow melt, reducing summer streamflows. Predicting spatial patterns of stream flow sensitivity associated with snowpack change is complicated by the influence of bedrock geology on the rate at which recharge (snowmelt or rain) becomes streamflow. Within the Oregon Cascades, distinct hydrogeologic differences between the younger High Cascade province and the older Western Cascade province are dominant controls on drainage rates and ultimately streamflow. In this doctoral dissertation research project, the doctoral candidate will use a process-based hydrologic model (RHESSys) to predict distributed streamflow sensitivity to climatic change within the McKenzie River basin, a major Willamette River tributary. Fieldwork will monitor streamflow and produce a framework to distribute model parameters. Streamflow predictions will be integrated with reservoir models to assess the sensitivity to potential climatic change for three large reservoirs in the McKenzie watershed. The objective of this study is to provide a better understanding of the interaction among the controls of snowpack and geology on streamflow at multiple scales and its response to climatic change in the Oregon Cascades. The results of this research will have important implications for water resources management and reservoir operations that utilize streamflow for recreation, power generation, municipal supply, and to help regulate aquatic habitat. The methods employed by this research, including the explicit inclusion and integration of snow accumulation, snow melt, groundwater drainage patterns, and reservoir operations, are methods that can be applied to modeling and climatic change inquiry in other systems, including those without substantial streamflow records. This research complements ongoing larger research initiatives designed to characterize the spatial structure of climatic change impacts on water resources within the mountains of the western U.S. This award will support an undergraduate field assistant, and as a Doctoral Dissertation Research Improvement Award, will also provide support to enable a promising student to establish a strong independent research career