ASSESSING CLIMATE CHANGE IMPACT ON DESIGN STANDARDS OF HYDRAULIC STRUCTURES

摘要

Design of hydraulic structures such as drainage infrastructures is mostly based on the premise that the current climate is not changing and that historical climate data can be used to plan future drainage requirements. However, recent climate change studies indicate an increase in the intensity and frequency of extreme rainfall events in most parts of Ontario. Therefore, this study investigates the possible impacts of climate change on drainage infrastructure design in the Grand River Basin of southern Ontario. Daily precipitation time series are downscaled from the Canadian Global Circulation Model (CGCM2) outputs to establish one possible scenario of future rainfall intensities in the study area. Besides the increasing trend in precipitation intensity in the historical data of the last 40 years, the scenario analysis shows that the future storm intensity may increase in the order of 18% and 28% by 2050s and 2080s respectively. The study also shows that drainage structures designed for a 10-year and 50 year storm events at the present time will only be able to withstand a 5-year and 20-year storms by 2050s respectively. In general, the results of this study indicate that the existing drainage design standards in Ontario may need to be revised so that drainage infrastructures built in the region could safely sustain possible future heavy storm events associated with the changing climate.