Evaluating Urban Storm-Water Infrastructure Design in Response to Projected Climate Change

One of the goals of storm-water infrastructure design is to mitigate effects resulting from extreme hydrologic events. Projected changes in climate are expected to lead to an increase in the frequency and magnitude of extreme rainfall events for many regions. Accordingly, existing storm-water infrastructure may not meet design standards in future decades. The North American Regional Climate Change Assessment Program is currently disseminating high resolution climate data to facilitate climate change impact assessments. A simple framework is presented for assessment of storm-water infrastructure in response to climate change. First, the projected changes in the 6-hour, 100-year design-storm depth for a watershed in Las Vegas Valley, Nevada, are calculated from several climate scenarios by using regional frequency analysis. Climate model projections vary substantially for this region and time scale. Climate model performance is assessed by using gridded reanalysis data. The projected changes in design-storm depths are incorporated into an existing HEC-HMS model. The HEC-HMS simulation results indicate potential exceedences of current design standards for select storm-water infrastructure components under projected climatic change scenarios.