Ontario Drainage Engineers Conference 21 October 2016 Guelph, Ontario Presented by: Hani Farghaly, PhD., P.Eng. Drainage and Hydrology Group Design and Contract Standards Office, MTO
This presentation will cover two new applications that MTO has recently introduced to ministry designers New Empirical Method for Flow Calculation in Ontario Updated IDF Curve Application V3 Climate Change Predictions 2
New Empirical Method for Flow Calculation in Ontario
Hydrographic Methods Empirical Methods Using Stream Flow Rate Record MIDUS Rational Method CFA OTTHYMO Modified Index Flood Other Single Event Northern Ontario Continuous Event Methods A comprehensive and description list of these software is provided in the MTO Software Evaluation Web site. 4
The MIFM and NOM equations were last updated in 1996. The MTO identified the need to develop an updated method that utilizes more up-to-date rainfall and stream gauge data. 5
The new method was developed as a joint project with the University of Toronto The method is based on the study titled Flood Frequency analysis for prediction of Peak Flows to reflect current climatic conditions in Ontario It is referred to as the Unified Ontario Flood Method (UOFM) It was implemented in MTO designs in March 2016 6
The UOFM is based on the Regression of flood quantiles statistical analysis. This approach utilizes relation between any quantile and basin characteristics. This is considered conceptually an improvement over the index flood as it can be developed for less frequent floods. Limitation: data used should represent natural flood conditions and unaltered natural flow 7
Range of parameters used to establish the equations Minimum Maximum Mean Median Boreal Shield (No. of stations=43) Standard deviation Area (km 2 ) 1.80 4416.77 908.36 404.53 1189.88 Mixed Wood Plains (No. of stations=75) Area (km 2 ) 13.16 1230.39 243.00 163.91 241.97 8
This method is based on the following regression equation: Where QQ UUOOFFMM = KK RR AA aa LLII bb PP cc Q UOFM = annual flood with a T year return period (m 3 /s); A = drainage area (km 2 ); LI = lake attenuation index =1 + WWWW WA = area of wetlands P = mean annual precipitation (mm) (Isohyetal map or other sources); K R = 10 x (x = from Table 3 on next slide) a, b and c are from Table 3 AA 9
Based on Climate Normals 1981-2010 10
Table 3: Coefficients of the Regression Model and Output summary T x a b c Boreal Shield 2-10.870 0.839-4.633 3.583 10-8.583 0.795-4.522 2.917 25-7.834 0.779-4.510 2.703 50-7.371 0.769-4.520 2.572 100-6.967 0.759-4.541 2.457 Mixed Wood Plains 2-5.483 0.756-3.061 1.837 10-4.139 0.734-3.780 1.491 25-3.680 0.728-4.017 1.372 50-3.397 0.724-4.162 1.299 100-3.151 0.721-4.287 1.236 11
Table 5: Range of Quantile Estimates T Standard error (log units) Boreal Shield Lower limit Range of Quantiles Upper limit 2 0.159-31% 44% 10 0.174-33% 49% 25 0.183-34% 52% 50 0.189-35% 55% 100 0.195-36% 57% Mixed wood Plains 2 0.147-29% 40% 10 0.165-32% 46% 25 0.177-33% 50% 50 0.186-35% 53% 100 0.195-36% 57% 12
Step 1: Obtain the latitude and longitude of the ungauged location Latitude: and Longitude Step 2: Identify the region in which the drainage basin is located from the ecozone map of Ontario (Figure 1) Step 3: Obtain the physiographic parameters required in the regression equations from OFAT Step 4: Obtain the mean annual precipitation for the station from the IsoHyetal map shown in Figure 2. Step 5: Using the regression equation and respective coefficients from Table 3 the regression T year flood Quantiles, QUOFM, are calculated for the specific region where the station is located. Step 6: The standard errors of the regression equation is to be used to establish the lower and upper limit of the prediction. These percentages are applied to the quantile estimates from Step 5. The final values for T-year quantile are established 13
Value used in Conveyance Design Value used in Conveyance Design UOFM MIFM UOFM MIFM The UOFM is generally an improvement on the other empirical methods. However, if other methods provide a higher value, the upper limit represents a possible flow condition that is more conservative and may better reflect the actual flows. 14 14
Station ID 02GB009 02MB006 Return Period (yrs) Q T Q MIFM Q UOFM Lower limit of Q UOFM (m 3 /s) Upper limit of Q UOFM (m 3 /s) Error MIFM (%) Error UOFM (%) 2 35.21-21.98 15.67 30.84 - -37.6 2.33-16.71 - - - - - 10 60.50 27.62 38.39 26.25 56.13-54.3-36.5 25 71.38 34.10 46.53 30.95 69.94-52.2-34.8 50 78.88 39.56 52.45 34.18 80.49-49.9-33.5 100 85.96 45.01 58.52 37.35 91.69-47.6-31.9 2 25.57-18.71 13.34 26.25 - -26.8 2.33-7.44 - - - - - 10 38.00 12.30 29.64 20.27 43.33-67.6-22.0 25 44.06 15.19 34.79 23.14 52.29-65.5-21.0 50 48.49 17.62 38.45 25.05 59.01-63.7-20.7 100 52.85 20.05 42.18 26.92 66.09-62.1-20.2 Grey indicates that the predicted quantile is less than the observed value (Q T ) 15
Station ID 02KF017 02DD015 02CA002 02DD013 Return Period (yrs) Q T Q MIFM Q UOFM Lower limit of Q UOFM (m 3 /s) Upper limit of Q UOFM (m 3 /s) Error MIFM (%) Error UOFM (%) 2 12.97-18.39 12.75 26.52-41.8 2.33-16.88 - - - - - 10 21.83 24.88 31.66 21.21 47.25 14.0 45.0 25 26.20 29.62 38.46 25.24 58.62 13.0 46.8 50 29.44 33.47 43.65 28.25 67.45 13.7 48.3 100 32.66 37.61 48.13 30.72 75.41 15.2 47.3 2 16.32-25.11 17.41 36.21-53.9 2.33-13.96 - - - - - 10 24.50 20.57 39.20 26.26 58.51-16.0 60.0 25 28.49 24.49 46.20 30.31 70.41-14.0 62.1 50 31.42 27.68 51.46 33.31 79.53-11.9 63.8 100 34.30 31.11 55.87 35.66 87.53-9.3 62.9 2 28.49-23.48 16.28 33.86-17.6 2.33-15.64 - - - - - 10 48.98 23.05 37.61 25.19 56.15-52.9-23.2 25 59.97 27.44 44.70 29.335 68.13-54.2-25.5 50 68.30 31.01 50.07 32.403 77.37-54.6-26.7 100 76.75 34.85 54.61 34.85 85.56-54.6-28.8 2 12.93-12.88 8.93 18.58 - -0.4 2.33-8.16 - - - - - 10 19.78 12.03 20.99 14.06 31.33-39.2 6.1 25 23.13 14.32 25.07 16.45 38.21-38.1 8.4 50 25.59 16.18 28.14 18.21 43.48-36.8 9.9 100 28.02 18.18 30.74 19.62 48.16-35.1 9.7 Grey indicates that the predicted quantile is less than the observed value (Q T ) Yellow indicates that the predicted quantile is greater than the observed value (Q T ) 16
Hydrographic Methods Empirical Methods Using Stream Flow Rate Record MIDUS Rational Method CFA OTTHYMO Modified Index Flood Other Single Event Northern Ontario Continuous Event Methods Unified Ontario Flood Method (New) A comprehensive and description list of these software is provided in the MTO Software Evaluation Web site. 17
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The development of the new MTO IDF curves has been a significant component of MTO s climate change strategy It relies on applying the latest available rainfall data to account for the most recent rainfall event in the development of the IDF curves used in the design of MTO drainage infrastructure 20
MTO published the first and second versions of the webbased rainfall IDF curves application in January 2011 and June 2014, respectively. The ministry will soon be introducing a new update of the application (Version 3). This update was developed as a joint project with the University of Waterloo. 21
The new online application has a number of enhancements: It uses data from outside Ontario within 150 km from the boarder including: 2012 release of Environment Canada IDF curves 2013 Quebec and Manitoba 2014 NOAA stations This address some anomalies at the provincial boundaries 22
1. Improved the statistical analysis resulting in better fit of interpolated data 2. Changed the map interface to make it easier to use, view, and navigate the online application 3. Added the capability to import shape-files representing watershed boundaries 4. Updated background information on the analysis methods, data used and acknowledgements included in the About section of the online application page 5. Added the capability to provide IDF curves for future years 23
Go To IDF Online Application 24
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A Provincial Engineering Memo has been prepared and ready for release to introduce the new online tool The memo will be released once the IDF application is available on the MTO Web site Projects that are already underway on the implementation date and where the hydrologic analysis for drainage design has been completed are not required to apply the updated IDF curves 29
Link to MTO Online Library: https://www.library.mto.gov.on.ca (Search for Unified Ontario Flood ) Link to IDF Curves: http://www.mto.gov.on.ca/idf_curves/terms.shtml 30