Monadnock Region Transportation Infrastructure Flood Vulnerability Assessment
- July 15, 2025
- Transportation
Some of the most pressing threats to infrastructure in Southwest New Hampshire are extreme storms and flooding. Extreme rainfall events in 2005 (Alstead) and 2006 (Keene and surrounding communities) brought severe flooding, resulting in costly road washouts, property damage, and loss of life. The trend of increased frequency and intensity of weather events is well-documented in meteorological records and federal disaster declarations. Much of the Region’s stormwater and roadway infrastructure (e.g., culverts and bridges) is aging and in need of repair, and does not have the capacity to handle the extreme storms and flooding experienced in recent years. Ongoing and future changes to our climate are expected to result in sudden, excessively high water volume storm events, risking significant impacts and higher maintenance costs for our transportation infrastructure. For example, the 2021 New Hampshire Climate Assessment found that annual precipitation in the state increased 8.1 inches or 19% since 1901 and 3.7 inches or 8.7% since 1971.
For the first time ever, SWRPC staff have utilized the Federal Highway Administration’s Vulnerability Assessment Scoring Tool to score the vulnerability of each publicly-maintained stream crossing or bridge in the Region to flooding based on its exposure, sensitivity, and adaptive capacity and published our findings in a report called the Monadnock Region Transportation Infrastructure Flood Vulnerability Assessment. The report and the full table of results showing scores for each asset are shown below. In addition, we have created an interactive map to view the results. Through SWRPC’s work, we intend to use the report’s findings to support local, regional and state transportation-related planning documents that focus on associated topics like maintenance and asset, risk and hazard management. It is also intended to help support SWRPC’s future transportation project prioritization and decision-making efforts.
