Numerous studies report that intensified precipitation resulting from anthropogenic climate change will stress civil infrastructures. Communities may have a window of opportunity to prepare, but information to support adaptation programs is sparse. For a small city’s watershed, the present culvert system’s capacity for conveying expected peak flow, Qp, resulting from climate change and full build-out was assessed. Least squares regression was used to transfer, to the study site, expected increases to point process location, scale, and regionalized shape parameters for 6 grid points from the GFDL CM-2.1 GCM. Runoff rates and Qp were modeled by the NRCS TR-55 curve number method and HEC-22. Standard civil engineering methods were used to reverse-engineer existing culverts, and replacement costs were estimated using national construction cost estimators. The mid-21st century 25-year precipitation is estimated to be 19% greater than the historical 25-year precipitation. This rate is similar to the 15% rule of thumb proposed by previous research. 43% of culverts likely will be undersized as a result of climate change and population growth, placing people and property at risk. A long-term upgrade program, utilizing existing strategies to manage uncertainty and costs, may maintain historically acceptable risk levels. The scientific, professional, and political communities remain concerned about the significant uncertainy that has not been eliminated from either GCM output or downscaling. However, numerous developments including scientific advancements, uncertainty management techniques, and increasing manifestation of climate change impacts, obviates the prudence of a "wait-and-see" strategy. This study proposes that current GCM output and statistical methods can generate reliable and specific estimates of impacts from climate change, in support of programs to adapt civil infrastructures.

Last Updated: 2007-03-16