HAPpy Hour Seminar: Century long hydroclimate ensemble datasets for Water Resources Planning in the US Pacific Northwest

Abstract: Currently, long-term water resources planning does not fully incorporate process understanding of hydrological variability, driven by climate dynamics and their potential future change. Furthermore, sequences of meteorological events affecting streamflow dynamics are as critical to infrastructure vulnerability as the impacts of individual events, more so if more extreme events are involved; yet the meteorological sequencing is not incorporated in the modeling used for the current planning. To address these limitations, a process oriented climate-hydrologic modeling chain is utilized to simulate 150-yr hydrologic conditions in the Pacific Northwest including Columbia River. Specifically, the approach begins with downscaling the coarse resolution outputs from the state-of-art Earth System models using computationally-efficient weather modeling, and then inputs them into a catchment-based, process-based hydrologic modeling system. The resulting 1950-2099 daily hydrologic traces at ~90,000 river reaches are being scrutinized for applicability to vulnerability assessments and resilience planning for the reservoirs by the US Army Corps of Engineers and its partners in the Pacific Northwest. This presentation covers: 1) large domain, hydrologic model implementation with focus of calibration strategy, 2) evaluation of historical streamflow simulations at ~200 reconstructed natural flow sites, and 3) characterization of future hydrologic variability and extremes. Time permitting, discussion may include physical mechanisms that cause the projected hydrologic changes, such as change in precipitation patterns due to shifts in winter atmospheric river events, change in evapotranspiration and seasonal snowpack due to future warming.

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