This project aims to understand the resilience of existing major stormwater infrastructure to different future climate and land-use scenarios.

We are focusing on culvert assets owned by the Pennsylvania Department of Transportation, which comprise more than 10,000 state-owned assets. These systems allow water from streams or open-drain channels to safely flow under roadways, and they were designed using historical precipitation records to determine the optimal design dimensions while balancing costs and risks.

Once the size of these culverts was determined, and they were built, its capacity remains fixed. There is evidence that streamflows in many regions are likely to change due to climate change, and these systems will require adaptation to these changes so that they can provide the expected level of service throughout their remaining service life. However, there is considerable uncertainty on the timing and magnitude of changes in extreme rainfall, which makes it challenging to update current standards.

Assessing installed conveyance capacity of long-lived infrastructure such as culverts can help stakeholders understand the resilience of infrastructure to increases in streamflow and enable targeted adaptation efforts for undersized structures. In some cases, adaptation actions in the form of watershed management and land-use actions might mitigate the requirement for oversizing culverts for future climate change impacts. Infrastructure managers need a method that supports robust decision making to maintain the intended performance of culverts over their multidecadal service life under a changing climate. We have developed a GIS-based automated screening tool to identify watersheds where culverts are over- and under-sized for current and future (2050-2100) rainfall. The method relies on open-source software and data, widely used culvert design engineering methods and relies on results from Project 3 in which we compared downscaled GCM projections from different publicly available datasets.