Freshwater researchers hope that their advances in understanding floods in coastal Washington watersheds will eventually be useful for giving local residents more warning for when flood waters will be reaching their properties.  In the photo below, Greg Platt moves bicycles to higher ground during a November (2015) flood of the Skagit River near Sedro-Woolley, WA, where heavy rainfall regularly pushes the Skagit River above its flood level.   During this flood, Platt said "It's not too bad right now, it won't get much higher than this"

Prediction Of and Resilience Against Extreme Events: Landslides and Floods (NSF-PREEVENTS)

Damage from natural disasters can be prevented by using predictions to improve our planning. With the objective of improving flood and landslide prediction, a collaborative researcher team led by University of Washington Civil & Environmental Engineering (CEE) has received a four-year $1.7 million National Science Foundation (NSF) Prediction of and Resilience Against Extreme Events (PREEVENTS) grant.

The grant is part of a larger $18.7 million investment by NSF’s PREEVENTS program, which is funding a total of 15 projects that aim to improve natural hazards predictability and resilience in order to better protect human lives. The program funds research on a variety of natural disasters, including hurricanes, earthquakes, wildfires and extreme precipitation.

The research team will be led by associate professor Erkan Istanbulluoglu and professor and co-investigator Alexander Horner-Devine, who will work with researchers from UW CEE, Earth and Space Sciences, the Climate Impacts Group, United States Geological Survey, and the National Park Service. The project was developed through the UW College of Engineering’s Mountains to Sea Initiative, which fosters water sustainability research at UW.

“Our research will introduce a dynamic perspective for flood prediction, integrating earth, atmospheric, and ecosystem science with engineering,” Istanbulluoglu said. “Existing flood prediction technology neglects the contribution of geomorphic events on flood risk. The challenge is that sedimentation events are random in nature and their timing and magnitude are not easily predictable.”

Although flooding is typically attributed to heavy precipitation, there is growing evidence that floods are often caused by excess sediment. Sediment is mobilized by a variety of factors, including retreating glaciers, droughts, wildfires, land-use changes and extreme rainfall. The sediment, which comes in various forms such as pebbles, sand or mud, and even boulders, can build up over time and prevent a river channel from containing excess floodwater (Figure 1).

Since current flood prediction tools do not factor in sediment dynamics, the researchers plan to develop new models that track sediment from landslides and other debris flows in streams. They will also model sedimentation processes in lowland rivers and deltas and simulate sediment impacts on river hydrodynamics and flooding. The researchers will create a mountain-to-coastline (M2C) flood modeling framework by integrating numerical models of glacio-hydrology, sediment dynamics and hydrodynamics. Extensive data will be used from existing field measurements, high-resolution satellite imagery, aerial photography and LiDAR.

The project will also inform the development of online tools for interactive flood mapping and comparisons with existing flood forecasting tools developed by the National Weather Service. Models and data will be shared through HydroShare, an online data repository for water researchers. The M2C modeling framework will build on existing NSF-funded projects that developed Landlab  (http://landlab.github.io/#/) and HydroShare (https://www.hydroshare.org/), and will use model building technologies developed by NSF sponsored CSDMS (http://csdms.colorado.edu/wiki/Main_Page), as well as data and model-sharing tools in development by UW Freshwater scientists.

To evaluate the new models, the researchers will apply the M2C framework to the Skagit River along with the Puyallup and Nisqually rivers draining Mount Rainier. Mount Rainier contains the largest glacier volume in the contiguous U.S., and these glaciers have been retreating over the past century.  As glaciers retreat they expose sediment to erosion. This newly exposed sediment is carried downstream, where it is deposited in river channels, leading to more frequent flooding by reducing the holding capacity of river channels (Figures 2, 3). Sediment in the Skagit River originates from Glacier Peak, landslides from steep forest land, and lowland landforms in the Skagit River basin.

UW research partners include co-principal investigator and Earth and Space Sciences senior lecturer Brian Collins; co-principal investigator and Climate Impacts Group research scientist Guillaume Mauger; co-principal investigator and CEE research scientist Christina Bandaragoda; CEE assistant professor David Shean; CEE professor Jessica Lundquist; and CEE assistant professor Nirnimesh Kumar. United States Geological Survey researchers are Kris Jaeger, Scott Anderson and Erin Whorton. National Park Service researchers are Paul Kennard, Scott Beason and Darin Swinney.