Investigating the Effects of Extreme Rainfall Trends on Existing Water Infrastructure and Design Considerations across the Connecticut River Basin

Various research efforts investigate the direct effects of climate change on hydrometeorological variables, yet the incidental consequences of extreme rainfall trends on existing infrastructure and/or future design considerations have not been thoroughly evaluated. Hydrological modeling for the design of water infrastructure usually includes precipitation fields transformed by climate change factors, which simply account for the relation (in most cases through a ratio) between past and future Intensity-Duration-Frequency (IDF) values, with the application of safety factors on the yielded results. While the latter occasionally account for epistemic uncertainties introduced by the choice of the IDF estimation techniques and/or the extensive incorporation of climate model simulations, they may lead to oversized structural components that are costly and could potentially prove ineffective. Moreover, the employment of high-resolution distributed hydrological models over extensive areas can be computationally cumbersome, while adding an additional layer of uncertainty. In this study, we attempt to assess the vulnerability of existing water infrastructure and reduce the effects of random variability in future planning through a statistical framework that encompasses the extreme rainfall trends derived by Emmanouil et al. (2022). To do so, we initially employ a series of distributed hydrological model simulations driven solely by historical data over the Connecticut River Basin, to establish a parametric relation between extreme rainfall quantiles and the simulated streamflow. Based on the foregoing relationship and actual infrastructural information of an existing stormwater drainage system, we develop a probabilistic design scheme that takes into consideration the effects of climate change on rare precipitation events, without the need to conduct arduous hydrological simulations for future conditions.

References

Emmanouil, S., Langousis, A., Nikolopoulos, E. I., & Anagnostou, E. N. (2022). The Spatiotemporal Evolution of Rainfall Extremes in a Changing Climate: A CONUS-Wide Assessment Based on Multifractal Scaling Arguments. Earth's Future, 10(3). https://doi.org/10.1029/2021ef002539