Rainfall Intensity Duration Frequency Curves Under Climate Change: City of London, Ontario, Canada

Figures & data

Figure 1. Flowchart of procedure for the CC_LB scenario (shuffling and perturbing an unmodified historical rainfall record) and CC_UB scenario (shuffling and perturbing a modified historical rainfall record using climate change factors from GCMs). In both cases, synthetic climate records are created using the Weather Generator which are then used to produce intensity-duration-frequency curves for the lower (CC_LB) and upper (CC_UB) bounds for a range of potential climate impacts.

Table 1. Change fields for CCSRNIES B21 scenario, used to modify historical rainfall records for the climate change upper bound (CC_UB) scenario (after Prodanovic and Simonovic, 2008).

Month	Change Field (CCSRNIES B21) (% change)
Jan	17.67
Feb	6.38
Mar	15.07
Apr	22.48
May	24.14
Jun	18.55
Jul	5.03
Aug	7.88
Sept	4.27
Oct	11.50
Nov	15.55
Dec	3.10
Average percent difference from base case for period 20402069 using grid cell centered at (43.01, 78.75).

Figure 2. Meteorological station used in the study (London Airport, Meteorological Services Canada ID: 6144475) in the Upper Thames River Basin of southwestern Ontario, Canada.

Table 2. Meteorological Service of Canada; London Airport rain gauge data.

Name#	Climate ID	Latitude (deg)	Longitude (deg)	Elevation (msl)	Avg. Annual Rainfall (mm)
London Airport	6144475	43.03	81.15	278.0	817.9
# Data between 19712000 are used.

Table 3. Nine Environment Canada rainfall elements (datasets) used as input into the weather generator model (after Simonovic and Peck, 2009).

Element*	Description (resolution)
125	Greatest amount of rainfall in 5 min (0.1 mm)
126	Greatest amount of rainfall in 10 min (0.1 mm)
127	Greatest amount of rainfall in 15 min (0.1 mm)
128	Greatest amount of rainfall in 30 min (0.1 mm)
129	Greatest amount of rainfall in 1 hr (0.1 mm)
130	Greatest amount of rainfall in 2 hr (0.1 mm)
131	Greatest amount of rainfall in 6 hr (0.1 mm)
132	Greatest amount of rainfall in 12 hr (0.1 mm)
010	Total rainfall (0.1 mm)
*Element number as provided by the EC technical documentation website, 2008 (http://www.climate.weatheroffice.ec.gc.ca/prods_servs/documentation_index_e.html).

Figure 3. Graph of intensity-duration-frequency curves for the climate change lower bound (CC_LB) scenario. These lines are created by shuffling and perturbing historical observed rainfall records for the London Airport Station. Rainfall magnitude and intensity for a range of durations and return periods (labelled in the upper right hand corner) are provided.

Figure 4. Graph of intensity-duration-frequency curves for the climate change upper bound (CC_UB) scenario. These lines are created by shuffling and perturbing modified historical rainfall records for the London Airport Station. Rainfall magnitude and intensity for a range of durations and return periods (labelled in the upper right hand corner) are provided.

Figure 5. Graph of intensity-duration-frequency curves adapted from Environment Canada for the London Airport station. Rainfall magnitude and intensity for a range of durations and return periods (labelled in the upper right hand corner) are provided.

Table 4. Depth (mm) for CC_LB scenario for various return periods.

	Return Period
Duration	2 yr	5 yr	10 yr	25 yr	50 yr	100 yr
5 min	11.0	14.9	17.5	20.8	23.3	25.7
10 min	16.3	23.2	27.7	33.4	37.6	41.8
15 min	19.9	28.6	34.4	41.6	47.0	52.4
30 min	25.4	36.7	44.2	53.7	60.7	67.7
1 hr	30.5	43.7	52.5	63.5	71.8	79.9
2 hr	37.2	52.7	62.9	75.9	85.5	95.1
6 hr	47.0	62.1	72.0	84.6	94.0	103.3
12 hr	53.2	69.8	80.8	94.7	105.1	115.3
24 hr	57.1	78.0	91.9	109.4	122.4	135.3

Table 5. Depth (mm) for CC_UB scenario for various return periods.

	Return Period
Duration	2 yr	5 yr	10 yr	25 yr	50 yr	100 yr
5 min	11.5	16.1	19.2	23.1	25.9	28.8
10 min	17.3	25.3	30.6	37.4	42.3	47.3
15 min	20.6	29.7	35.7	43.3	49.0	54.6
30 min	26.1	38.8	47.1	57.7	65.6	73.4
1 hr	30.6	43.6	52.2	63.1	71.1	79.1
2 hr	37.0	52.5	62.8	75.9	85.5	95.1
6 hr	47.4	63.4	73.9	87.3	97.1	107.0
12 hr	55.1	72.5	84.1	98.7	109.5	120.2
24 hr	61.4	84.2	99.2	118.3	132.4	146.4

Figure 6. Graph of intensity-duration-frequency curves for the 100-year duration for CC_LB, CC_UB and EC.

Prodanovic, P., and S. P. Simonovic. 2008. Intensity Duration Frequency Analysis under Changing Climatic Conditions. In Proceedings of the 4th International Symposium on Flood Defence: Managing Flood Risk, Reliability and Vulnerability. Toronto, Ontario, Canada, May 68, 2008, 8 pp.

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Simonovic, S. P., and A. Peck. 2009. Updated Rainfall Intensity-Duration-Frequency Curves for the City of London Under a Changing Climate, Water Resources Research Report No. 65. University of Western Ontario, London, Ontario: Facility for Intelligent Decision Support, Department of Civil and Environmental Engineering, 64 pp.

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