A Regional Hydrologic Vulnerability Assessment Protocol for Road-Stream Crossings

Recent flood events caused by tropical storms resulted in large economic impacts in the Northeastern U.S. and catalyzed efforts to understand the complex interactions between human and natural systems. Specifically, the resilience of our transportation infrastructure to climate and the impact of our transportation systems on the aquatic environment are important to both state and federal decision makers. In is important that new, innovative approaches be developed that consider both the robustness of our infrastructure today and its ability to cope with forecasted extremes due to climate change. This paper presents ongoing research associated with the broad regional application of a hydrologic vulnerability framework for road-stream crossings. A calibrated, process-based hydrological model is used to develop estimates of flood flows at various return frequencies. Road-stream crossings are identified and the maximum critical flows for these crossings are calculated. Daily-runoff from the hydrological model is coupled with a statistical index-method to determine the average recurrence interval for flood flows at ungaged locations. Finally, a vulnerability analysis is performed that maps the annual exceedance probability (AEP) of the critical flow through crossing infrastructure to the estimated AEP of flood flows at the crossing locations. This study supports the development of a decision-support tool for prioritizingculvert repair and replacement in the region. It also creates a more robust infrastructure design that suggests adaptation strategies in conjunction with climate information.