Trends in rainfall intensity for stormwater designs in Ontario

Abstract

The intensities of short-duration rainfall events are fundamental inputs to the design of stormwater management infrastructure. However, since stormwater infrastructure must function as designed for many decades, if there are long-term trends in rainfall intensities, design storms need to be modified. Evidence demonstrates, using data from 13 rain gauges in Ontario, that storm intensities relevant to urban stormwater (5 year) appear to have changed over the last 30 years. The resultsshow, for example, statistical significance at 80% confidence that the 5-year storm has increased, and 85% that the 2-year storm has increased, for the 1 h storm in Waterloo, using partial duration series (PDS) data. The PDS data indicate intensities are increasing at a rate of 1-3% per year. Results show, for example, that a 5-year recurrence storm for PDS for the period 1970-1984 is now very close in magnitude to a 2-year recurrence storm for the period 1985-2003 for Waterloo, Ontario. The implications for a case study demonstrate that 5 out of 12 storm sewer pipes in a subdivision would need to be increased in diameter to obtain the same level of stormwater performance.

Increased Risks of Waterborne Disease Outbreaks in Northern Ontario due to Climate Change

“…The results presented in this study, in general, are in agreement with recent climate change studies in Ontario (Asnaashari et al 2015;Rudra et al 2015;Vasiljevic et al 2012).…”

The Effectiveness of Exfiltration Technology to Support Sponge City Objectives

“…(1) I = 13.9 × (1 + 1.091 Log 10 (Tr))/(D + 10) 0.759 for D from 120 to 360 min (2) where 'I' is rainfall intensity in mm/min, Tr is the return period in years and D is the duration in minutes, as per Table 1. SWMM was used to estimate the quantity of stormwater entering the storm sewers following sizing based on the rational method and subsequently evaluated using SWMM.…”

“…By 2050, it is projected that more than 70% of the human race will be in urban settings, with many of these urban settings located in mega-cities [1]. Challenges facing these large urban cities include two particular water-related dimensions, namely (i) urban flooding, in part due to the transformation of the landscape from pervious to significant levels of impervious land uses, plus the more intensive, heavy storms that are expected to occur as a result of climate change (e.g., References [2][3][4]), and (ii) in the search for sufficient supplies of water to satiate the burgeoning urban populations, large groundwater withdrawals may be resulting in land subsidence (e.g., see Reference [5]). Cities in northern China experience arid and semi-arid climates, with an average annual rainfall of less than 600 mm, with the precipitation concentrated within the rainy season from May to October.…”

Prediction vs. Performance of IDF Curves from Precipitation Data of Regional Climate Models for a Brazilian Coastal County

“…Vasiljevic et al [50], analyzing two different periods, (1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984) and (1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003), noticed that storm drainage pipes would need to be larger in diameter due to the increased design rainfall intensities. Liew et al [24] reported the lack of long rainfall records, which is common in most Southeast Asia countries and leads to the improper designs of urban drainage systems.…”