Anatomy of Floods in the Coastal Mountains of the Pacific Northwest, USA

In coastal mountains, flood frequency and magnitude can be controlled by a range of factors including extreme climatic conditions, watershed runoff response, and dynamics of snow, cryosphere, sediment, and channel capacity. Understanding the relative contributions of these factors to flood generation is critical to improving flood modeling. We investigate flood generation in the Pacific Northwest (PNW) using examples from recent floods in the Puyallup river basin that drains glaciated stratovolcano Mount Rainier and complex patterns of land use including forestlands, suburban, urban, and industrial. Our approach integrates gridded hydrometeorological forcing data from observations and atmospheric models, high spatial resolution distributed hydrologic modeling, and satellite remote sensing geospatial data for snow and ice. Results focus on improved representations and modeling of hydrometeorological forcing of Atmospheric Rivers, snowmelt and cryospheric dynamics on flood generation. Such enhanced hydrologic representation will serve as a foundation for coupled simulations of the dependencies of geomorphologic and hydrologic processes for flood hazards in the PNW region.