Many national and experimental forests are crisscrossed by gravel roads that contain culverts and other drainage structures. Some culverts may be overdue for maintenance, while others may be too small for extreme rainfall events.
U.S. Forest Service Southern Research Station scientists began assessing the capacity of these structures in 2016. The project spans the SRS Experimental Forest network.
The design of most stormwater routing structures is based on historic or current climate conditions. However, precipitation conditions are shifting and projected to keep changing in the future.
Understanding the influence of these changes in precipitation intensity, duration, and frequency, the resulting stormwater responses, and vulnerability of infrastructure from headwater catchments to watershed outlets is key to the design of sustainable road systems.
SRS researchers are assessing the capacity of these drainage structures and their vulnerability to extreme precipitation. The project involves reviewing historic data products – in paper format, filed away in boxes and cabinets. The data show how precipitation patterns have changed and how the changes could affect stormwater flows and infrastructure designs.
The project is focusing on three southern Experimental Forests (EFs) with different elevations and ecoregions: Alum Creek EF in central Arkansas, Coweeta Hydrologic Laboratory in the mountains of North Carolina, and Santee EF in the coastal plain of South Carolina.
Led by research hydrologist Devendra Amatya, researchers are:
- Describing the landscape features and climate of each site.
- Using each site’s long-term precipitation data, describing trends in heavy precipitation, the duration of those storms, and how or if that is changing over time.
- Assessing and describing the current road systems on site and the size of all culverts.
- Coupling the road descriptions with the long-term datasets to make preliminary assessments of vulnerability and risks for the above analyses.
In addition, SRS intern Jessica Allen digitized historic strip charts from gages at Santee and Alum Creek EFs. Allen extracted precipitation volume, intensity, and duration data from more than 30 years of historic charts. Her work is a collaboration between the Southern and Northern Research Stations and an effort to catalog historic datasets in the Research Data Archive.
Eventually, the project will inform design and management of road infrastructure for resiliency. A pilot study on the Francis Marion National Forest is beginning to use early results from this work to aid in the development of the National Transportation Resiliency Guidebook (in review).
For more information, email Stephanie Laseter at email@example.com.