Rapid proposal: Fires and floods: Acquisition and analysis of perishable data on the sustainability of reservoirs following wildfires

Oregon State University, Corvallis OR

Investigators

Abstract

Desiree D. Tullos A RAPID grant situation has been generated by the fire-flood regime being experienced in the Western U.S. The combination of the extensive burns from 2015 wildfires, followed by the forecasted severity of precipitation under the "monster" el nino season ahead, is expected to generate substantial failure and erosion of hillslopes, resulting in more severe sediment yields at times that are difficult to predict. These sediment loads may generate important impacts to reservoirs and water distribution systems, though these potential impacts are not well understood. As the severity and extent of wildfires and floods are forecasted to increase in the future, the need for advancing understanding on and modeling of post-fire flooding impacts to water infrastructure is urgent. The objective of this project is to collect perishable data that will lead to understanding if, how, and where sediment delivered from burned and flooded basins may reduce the functional life of reservoirs. Given that the rainy season typically begins in late November to late December, this is a time sensitive and field intensive study, and the PIs will deploy teams rapidly to document the real-time responses to fires and floods. The scope of activities includes: a) estimate the relative and absolute yields of sediment throughout a wet water year following extensive burning, distinguishing sediment delivered from burned and unburned tributaries in the Mad River basin, California, to establish sedimentation generation rates associated with fire, b) survey bathymetry of and sediment cores from Ruth Reservoir prior to and following the flood season to calculate short-term sedimentation rates associated with burned and unburned areas, and c) apply models of trap efficiency and reservoir capacity to calculate long-term sedimentation rates due to precipitation alone and due to wildfires-flood scenarios. Results will 1) provide evidence on the processes responsible for and the timeline at which reservoir capacity may be impacted by the changing fire-flood regime; 2) demonstrate a methodology, and preliminary data, for conducting this research across geographical scales; and 3) develop data necessary to developing regionally-specific models (e.g. debris flow thresholds and sediment yield decay) that are widely used by managers in mapping and communicating post-fire hazards. This project will impact society by 1) advancing knowledge on wildfire-flood impacts on water infrastructure, 2) developing that can be applied in future studies to advance models and understanding on the landscape-scale processes and interactions that lead a basin to be more sensitive to post-fire sediment generation now and in the future, 3) contribute to national database on reservoir sedimentation to support national-scale, synthetic reservoir sedimentation studies; and 4) supporting planning for the long-term delivery of water to communities serviced by the study reservoir.