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Influence of Precipitation Intensity-Duration-Frequencies on Road Culvert Vulnerabilities at Three USDA Forest Service Long-term Experimental Forests in Varying Ecoregions
Citation:
Jalowska, A., D. Amatya, J. Campbell, S. Johnson, K. Elder, N. Lany, K. Tamaddun, S. Panda, S. Laseter, J. Grace, AND A. Walega. Influence of Precipitation Intensity-Duration-Frequencies on Road Culvert Vulnerabilities at Three USDA Forest Service Long-term Experimental Forests in Varying Ecoregions. AGU Fall Meeting 2021, New Orleans, LA, December 13 - 17, 2021.
Impact/Purpose:
This poster is a in colaboration with US Forestry Services on the projet looking at the state and prepeardeness of culverts on the USFS theritories for the rainfall under the changing climate.
Description:
Increased peak-flow magnitudes resulting from the growing intensity of extreme precipitation events might have adverse effects on existing infrastructure such as road culverts and drainage systems. Engineers and hydrologists often use precipitation intensity-duration-frequency (PIDF) curves published by NOAA for infrastructure design applications. However, it is unknown how a) site-specific PIDFs derived with experimental forest (EF) long-term (L-T) data compare to the NOAA PIDFs, b) the PIDFs have changed over time, and c) widely used empirical models (e.g. Rational, SCS-CN TR-55, and USGS Regional Regressions) using the PIDF estimates for design discharge estimates influence the design and vulnerability of road culverts on small headwater forest watersheds. This study proposes to analyze L-T precipitation and runoff data from three USDA Forest Service EFs in varying eco-regions: the 3,500 ha Hubbard Brook EF in the White Mountain National Forest (NH), with 11 rain and 9 stream gauges; the 9,320 ha Fraser EF in the Arapahoe/Roosevelt National Forest (CO), with 7 rain and 6 stream gauges; and the 6,240 ha HJ Andrews EF in the Willamette National Forest (OR), with 6 rain and 10 stream gauges. The study will i) develop design PIDFs for each gauge using the Generalized Extreme Value Distribution (GEVD) method and compare them with the corresponding locations from network of NOAA published interpolated values, ii) perform a PIDF trend analysis, iii) derive design discharges with applicable methods using on-site PIDF data, and compare them to on-site data-based Log-Pearson Type-III flood frequencies to evaluate their performance and uncertainties, and lastly iv) develop a geospatial modeling based road culvert vulnerability assessment tool to identify culverts/stream-crossings susceptible to failure due to scouring, sediment blockage and flooding for each EF. As a future step, the best performing flood discharge model for each EF will be applied to predict future design discharges using dynamically downscaled subdaily PIDF curves from projected general circulation models. This research has important implications for the design, rehabilitation and sustainable management of existing water crossings, road culverts and drainage structures as well as ecological applications at the EFs and surrounding National Forest lands.