Speaker: Naoki Mizukami, associate scientist, Research Applications Laboratory, National Center for Atmospheric Research (NCAR)
Topic: Large-domain hydrologic modeling for long-term water resource planning.

Abstract
Many water agencies are now looking into process-based models to understand how climate dynamics drive hydrological variability and their future change. For example, NCAR collaborates with U.S. Army Corps of Engineer and Bureau of Reclamation to generate spatially distributed hydrologic simulations, including river discharge, using a climate-hydrology modeling chain that accounts for uncertainties.

This talk discusses a model workflow for producing ensemble streamflow simulations over the Pacific Northwest domain from 1950 to 2099. The approach begins with selecting several Earth system models (ESMs) in Coupled Model Intercomparison Project-Phase 5 and 6, followed by downscaling the ESM outputs using computationally efficient weather modeling, and finally feeding the downscaled climate forcing into catchment-based hydrology and river modeling system. The resulting 29 hydrologic traces at 90,000 river reaches across the domain supports vulnerability assessments and resilience planning for the reservoirs of the US Army Corps of Engineers and its partners in the Pacific Northwest.

Key topics include: 1) Implementing and calibrating the large domain hydrologic models, 2) evaluating historical streamflow simulations at ~ 200 naturalized flow sites, and 3) Assessing future hydrologic variability,  extremes and seasonality shifts.

This process-based modeling chain allows us to examine the physical drivers of the changes in extreme streamflow events, such as changes in snowpack and evapotranspiration due the warming, and changes in precipitation pattern and intensity due to shifts of winter atmospheric river events.

Finally, we are now expanding this approach to the entire CONUS with improved parameter estimation methods. I will discuss the progress and challenges in this nationwide hydrologic modeling effort.

Bio
Naoki Mizukami is an associate scientist at NSF National Center for Atmospheric Research (NCAR), Research Application Laboratory. He holds a BS in Geophysics from Hokkaido University, Japan, and M.S. and Ph.D. in Civil Engineering from University of Utah. His research primarily focuses on the impacts of various modeling decisions, including parameter estimation methods, model structures, forcing choices, on model outcomes for water resources planning. Naoki also contributes to model development, particularly developing the river transport model that is coupled with NCAR Community Earth System Model over the last few years. Before joining NCAR, he worked at NOAA’s National Weather Service, Office of Hydrologic Development (now National Water Center) where he contributed to the development of Snow17 model for NWS river forecasting. --