LOISS Background Report APP A Hydrology and Hydraulics · 2012-03-01 · Hydrology and Hydraulics Report Lake Ontario Integrated Shoreline Strategy Aquafor Beech Limited 1 1 INTRODUCTION

CREDIT VALLEY CONSERVATION LAKE ONTARIO INTEGRATED SHORELINE STRATEGY BACKGROUND REVIEW AND DATA GAP ANALYSIS

APPENDIX A Hydrology and Hydraulics Final Report Prepared By: AQUAFOR BEECH LIMITED #6-202-2600 Skymark Ave Mississauga, ON L4W 5B2 May 5, 2011 Project No.: 64967

Hydrology and Hydraulics Report Lake Ontario Integrated Shoreline Strategy

Aquafor Beech Limited i

Table of Contents 1 Introduction............................................................................................................................. 1 2 Background Information......................................................................................................... 1 3 Technical Assessments ........................................................................................................... 2 4 Conclusions........................................................................................................................... 29 5 Data Gaps.............................................................................................................................. 29 List of Tables Table 3.1: Yearly Precipitation at Station 2.................................................................................... 5 Table 3.2: Yearly Precipitation at Station 9.................................................................................... 5 Table 3.3: Environment Canada Climate Normals ......................................................................... 7 Table 3.4: Summary of Watershed Characteristics......................................................................... 9 Table 3.5: Summary of Hydrologic Modelling by Subwatershed ................................................ 11 Table 3.6: Summary of Hydraulic Modelling by Subwatershed .................................................. 16 Table 3.7: Summary of Return Period Flows by Subwatershed................................................... 21 Table 3.8: Overtopped Structures ................................................................................................. 26 Table 3.9: Flooded Buildings within the Study Area ................................................................... 28 Table 3.10: Flooded Building within Entire Watersheds.............................................................. 28 Table 5.1: Summary of Missising Flow Data .............................................................................. 29 Table 5.2: Summary of Additional Missing Data......................................................................... 29 List of Figures Figure 3.1: Watersheds within Study Area ..................................................................................... 3 Figure 3.2: Location of Meteorological Stations ............................................................................ 4 Figure 3.3: Location of Environment Canada Climate Stations..................................................... 6 Figure 3.4: Mean Yearly Lake Ontario Water Levels at Toronto................................................... 8


Aquafor Beech Limited 1

1 INTRODUCTION

Hydrology is the science that deals with the interaction of water, the land, and the processes by which precipitation is transformed into runoff to the receiving watercourses or infiltrated into the groundwater system. One of the most dramatic changes brought about by urbanization is the change in stream hydrology. For example, the replacement of vegetation and undisturbed terrain with impermeable surfaces (i.e. pavement, roof tops, graded surfaces and the provision of an underground storm drainage network) results in greater interception of water that would naturally infiltrate into the ground, and instead provides a direct and rapid transport of surface runoff to streams. As a result, groundwater recharge diminishes which could, in turn, potentially affect baseflows in streams relying on groundwater discharge. A more rapid rate of stormwater runoff from rainfall events can result in an increase in the total volume, peak flow, and frequency of runoff occurrences. Uncontrolled, these hydrologic changes can result in increases in flooding, channel erosion, sediment transport, and pollutant loadings. These changes can also cause deterioration in natural channel morphology, fish and wildlife habitats, recreational opportunity, and aesthetics. It is important that the existing hydrologic characteristics of the Study Area and its watercourses be established. This information is critical in providing key information on the selection and design of stormwater management facilities for future urban development lands. Additionally, flows determined from hydrology are used as the basis for hydraulic studies. In the context of this study, hydraulics deals with the movement of water through streams and rivers. Thus, the combination of hydrology and hydraulics allows for the definition of existing flood characteristics and the Regulatory floodplain limits.

2 BACKGROUND INFORMATION

The following documents were reviewed to provide information relating to watershed characteristics, flood flows, floodlines, and inundated structures and buildings.

Aquafor Beech Ltd. (2005) Floodline Mapping Study: Sawmill, Carolyn and Tecumseh Creeks, report prepared for Credit Valley Conservation and City of Mississauga. Aquafor Beech Ltd. (2003) Floodline Mapping Study: Serson, Cawthra, Stavebank, and Lakeside Creek, report prepared for Credit Valley Conservation and City of Mississauga. Aquafor Beech Ltd. (2002) Turtle Creek Floodline Mapping Study, report prepared for Credit Valley Conservation and City of Mississauga. Credit Valley Conservation (2009) Sheridan Creek Watershed Study and Impact Monitoring, Characterization Report, Draft.



Environmental Water Resources Group Ltd. (2002) Cooksville Creek Flood Remediation Plan, report prepared for Credit Valley Conservation and City of Mississauga. Environmental Water Resources Group Ltd. (1996) Birchwood Creek Drainage Study, final report prepared for City of Mississauga. McCormick Rankin Corporation (2005) Clearview Creek Subwatershed Study, prepared for Park Mount Holdings. Golder Associates Ltd. (2005) Credit River Floodline Mapping Study, report prepared for Credit Valley Conservation and City of Mississauga. Philips Engineering Ltd. (2001) Applewood, Lornewood and Wolfedale Creeks: Hydrologic Modelling Assessment, report prepared for Credit Valley Conservation and City of Mississauga. Philips Engineering Ltd. (2003) Applewood Creek, Lornewood Creek and Wolfedale Creek Floodline Mapping Studies, report prepared for Credit Valley Conservation and City of Mississauga. Philips Engineering Ltd. (2007) Credit River Flow Management Study, report prepared for Credit Valley Conservation and the Region of Peel. Totten Sims Hubicki Associates (2000) Southdown District Master Drainage Plan, report prepared for City of Mississauga.

3 TECHNICAL ASSESSMENTS

The Hydrologic and Hydraulic component of this study involved summarizing watershed and watercourse characteristics from existing documents and data sources (see Figure 3.1 for the watersheds within the Study Area). The documents listed in section 2 were reviewed to provide the information required as outlined in Section 3.2.1 of the LOISS Summary Report. Additionally, precipitation data were supplied by Credit Valley Conservation while the water level record of Lake Ontario at Toronto was acquired from the Water Survey of Canada archives. Any missing data pertaining to the hydrologic and hydraulic component of the LOISS have been identified as the data gaps in Section 5.



Figure 3.1: Watersheds within Study Area



The City of Mississauga maintains ten rain gauging stations located within its boundaries. Half of these gauges are heated. Gauges 1, 2, and 9 are of interest to the LOISS as these gauges are located within, or close to, the limits of the Study Area (see Figure 3.2 for locations). The remainder of the gauges are located north of the Study Area and were not considered for this study. As seen in the figure below, Station 1 is the gauge closest to several of the subwatersheds. However, there were numerous gaps and errors in the data collected at this gauge and thus, this gauge was not considered in this study. Instead, data were provided by CVC for Stations 2 and 9. Station 2 is located within the Lakeside Creek Subwatershed within the Study Area. Station 9 is located north of the Study Area within the Sheridan Creek Subwatershed.

Figure 3.2: Location of Meteorological Stations Table 3.1 and Table 3.2 present the yearly precipitation data from the rain gauging stations. Based on the data provided, the Study Area receives an average of about 660 mm of precipitation per year. As seen in the table, the precipitation record is incomplete as days are missing in most years. There are at least three episodes for each station that have more than 50 days of missing data; this presents a shortcoming of these stations.



Table 3.1: Yearly Precipitation at Station 2

Year Total

Precipitation (mm)

Number of days missing

1995 669 18 1996 719 61 1997 534 37 1998 618 0 1999 584 43 2000 605 30 2001 670 8 2002 658 22 2003 601 53 2004 497 103 2005 649 3 2006 889 0 2007 457 0 2008 489 30 2009 757 2 Mean 626 27

Table 3.2: Yearly Precipitation at Station 9

Year Total

Precipitation (mm)

Number of days missing

1996 930 93 1997 516 22 1998 353 0 1999 515 61 2000 577 0 2001 719 0 2002 671 0 2003 832 0 2004 556 56 2005 694 16 2006 1085 0 2007 448 35 2008 925 30 2009 865 2 Mean 692 23

As a means of comparison, the Environment Canada Climate Normals for the Oakville Southeast WPCP and Pearson International Airport are presented in Table 3.3. The Oakville Southeast WPCP is located just south-west of the Study Area while Pearson International Airport is located north of the Study Area (see Figure 3.3). These data suggest that the Study Area receives a mean



annual precipitation of about 800 mm. Since the climate normals are based on a thirty year record, the precipitation depths in the table below are likely better representative of the long term mean in the Study Area. However, for individual precipitation events, there can be significant spatial variation. Thus, for individual events, the Station 2 gauge, located within the Study Area, would provide more appropriate data.

Figure 3.3: Location of Environment Canada Climate Stations (Source: Google Earth)

LOISS Study Area



Table 3.3: Environment Canada Climate Normals Precipitation (mm)

Period Oakville Southeast

WPCP

Pearson International

Airport Jan 58.8 52.2 Feb 44.2 42.6 Mar 61.9 57.1 Apr 67.6 68.4 May 70.3 72.5 Jun 71.3 74.2 Jul 72.9 74.4 Aug 78.4 79.6 Sep 78.5 77.5 Oct 68.8 64.1 Nov 71.5 69.3 Dec 64.6 60.9

Annual 808.7 792.7 Water levels in Lake Ontario were acquired from the Water Survey of Canada archives for the gauge at Toronto which has been recording water levels since 1906. Figure 3.4 shows the maximum, minimum, and mean yearly water surface elevations for Lake Ontario at Toronto. As seen in the figure, the water level in Lake Ontario at Toronto has a range of about 2 m over the period of record. The mean water surface elevation over the period of record is 74.8 m. Over the past decade, the mean yearly water surface elevations have been close to the mean for the period of record.



Figure 3.4: Mean Yearly Lake Ontario Water Levels at Toronto

General watershed characteristics are summarized in Table 3.4. The fraction impervious was not presented within the documentation provided for Avonhead Creek, Clearview Creek, the Credit River, or Sheridan Creek. No information was available for Cumberland Creek.



Table 3.4: Summary of Watershed Characteristics

Watershed Drainage Area (ha) Approximate Watercourse Length (km)

Landuse Imperviousness

(%)

Nearest Meteorological

Station*

Availability of Stream Gauge

Station

Applewood Creek 597 2.9 Residential, commercial,

and open space 46 Station 1 No

Avonhead Creek

233 (-32 diverted to Clearview)

(85 after additional diversion to Clearview)

3.4 Industrial N/A Station 2 No

Birchwood Creek 340 4.4 Residential, commercial,

institutional, and open space

25 (28% future land

use) Station 2 No

Moore Creek

Birchwood Creek 340 4.4 Residential, commercial,

institutional, and open space

25 (28% future land

use) Station 2 No

Cawthra Creek 604 Conveyed in storm

sewers except for 0.3 km

Residential, industrial, commercial, institutional

48 Station 1 No

Clearview Creek

314 (within Oakville) 68 (within Mississauga)

(+ 32 diverted from Avonhead)

1.8 (within Mississauga)

Residential, commercial, agricultural

N/A Station 2 No

Cooksville Creek 3390 16 Residential, commercial, industrial, and open space

47 Station 1 No+

Credit River 93,000 90 Residential, commercial,

open space N/A Station 1 No+

Cumberland Creek Station 1

Lakeside Creek 250

(95 Petro Canada)

Conveyed in storm sewers except for 0.2

km Industrial 21 Station 2 No

Lornewood Creek 411 2.4 Residential 25 Station 1 No Serson Creek 204 2.0 Residential, industrial 31 Station 1 No

Sheridan Creek 1,035 5.6 Residential, commercial N/A Station 2

Gauges installed Aug-Dec 2007 and Apr-Nov 2008 for

Sheridan Creek Watershed Study

and Impact Monitoring

Tecumseh Creek 167 1.7 Residential 33 Station 1 No

Turtle Creek 213 3.3 Residential, commercial,

industrial 40 Station 2 No

*See Figure 3.2 for location of meteorological stations +None located within the LOISS Study Area but Water Survey Canada gauges are found within the watershed north of the Study Area



Hydrologic and hydraulic models have been developed for the various watersheds within the Study Area. Table 3.5 and Table 3.6 summarize the details about the hydrologic and hydraulic models, respectively. The summary tables provide the name of the developer, year developed, name of the model used and any assumptions and recommendations provided in the studied reports. No information was available on the hydrologic model for the Credit River. No information was available on the hydrologic and hydraulic modeling or flood hazard mapping for Cumberland and Moore Creek.



Table 3.5: Summary of Hydrologic Modelling by Subwatershed Watershed Developer Year

Developed Name of Model

Assumptions Recommendations

Applewood Creek1

Philips 2001 OTTHYMO - -

Avonhead Creek2

TSH 2000 Visual OTTHYMO

- -

Birchwood Creek3

EWRG 1996 OTTHYMO - -

Cawthra Creek4

Aquafor 2003 SWMHYMO 1. Design storm approach selected assumes that the peak flows generated from this approach are of approximately the same return period as the applied storm.

2. The 24 hr Chicago type distribution used to determine 2-100 year, regional flows assumed that for a given return period, the design storm should represent the IDF curve and contain all maxima corresponding to various durations.

-

Clearview Creek2,5

TSH 2000 Visual OTTHYMO

1. Extended detention SWM wet ponds are recommended for water quality and quantity control for new and existing developments in the Study Area. The stormwater quality target for the study watershed is a Normal (Level 2) level treatment

1. Extended detention SWM wet ponds are preferred facilities for treatment of stormwater in new developments as well as in existing developments without SWM controls. However, where stormwater management ponds cannot be provided due to land availability, use of grassed swales should be considered.

2. An enhanced level of treatment to

Level 1 should be provided.



Watershed Developer Year Developed

Name of Model


3. Comprehensive pre, during and post construction monitoring should be conducted.

Cooksville Creek6

EWRG 2002 OTTHYMO 1. Peak flow rates are conservative as the values have been calculated assuming no storage behind road/railway embankments. Storage behind road/railway embankments attenuates peak flow rates which lead to lower downstream peak flow rates and water surface elevations.

It is recommended that the Authority should adopt the Regulatory Flood Plain to manage Flood Plain lands due to the large number of buildings within the Regulatory Flood Plain. Further study is recommended to determine means of alleviating potential flooding.

Credit River7

Philips 2007 Visual OTTHYMO - -

Cumberland Creek

- - - - -

Lakeside Creek4


2. The 24 hr Chicago type distribution used to determine 2-100 year and regional flows assumed that for a given return period, the design storm should represent the IDF curve and contain all maxima corresponding to various durations.

-

Lornewood Creek1

Philips 2001 OTTHYMO - -

Moore - - - - -




Name of Model


Creek Serson Creek4


2. The 24 hr Chicago type distribution used to determine 2-100 year and regional flows assumed that for a given return period, the design storm should represent the IDF curve and contain all maxima corresponding to various durations.

-

Sheridan Creek8

Winter 2000 Visual OTTHYMO

1. In absence of long term hydrometric data. Regional Flood Frequency Analysis was used to provide statistically based flood estimates. Regional Flood Frequency analyses are based on similar watersheds within a region which have long term historic flow data.

The peak flow estimates from the Visual OTTHYMO model are within the 50% confidence limits of the multiple regression method. Therefore, it is recommended that these peak flow estimates be used for the development of regulatory floodlines.

Tecumseh Creek9


2. The 24 hr Chicago type distribution used to determine 2-100 year, regional flows assumed that for a given return period, the design storm should represent the IDF curve and contain all

Standard values recommended by the CVC were used to estimate Manning’s roughness coefficients and initial abstraction/depression storage. These coefficients are based on vegetation observed during field investigations.




Name of Model


maxima corresponding to various durations.

Turtle Creek10


2. The 24-hr Chicago type distribution used to determine 2-100 year and regional flows assumed that for a given return period, the design storm should represent the IDF curve and contain all maxima corresponding to various durations.

3. Values for % impervious were assumed for various land uses to stimulate the existing urban development.

4. The 1-hr Chicago type distribution used to determine 2-100 year and regional flows assumed that for a given return period, the design storm should represent the IDF curve and contain all maxima corresponding to various durations.

-

Aquafor – Aquafor Beech Ltd. EWRG – Environmental Water Resources Group Golder – Golder Associates MRC – McCormick Rankin Corp. Philips – Philips Engineering Ltd. TSH – Totten Sims Hubicki Associates Winter – Winter Environmental Consulting (Note: Winter Environmental Consulting (2000) Sheridan Creek Flood Line Mapping Study not provided for LOISS but reference in CVC (2009) Sheridan Creek Watershed Study and Impact Monitoring.)




Name of Model


1 Philips Engineering Ltd. (2001) Applewood, Lornewood and Wolfedale Creeks: Hydrologic Modelling Assessment, report prepared for Credit Valley Conservation and City of Mississauga.

2 Totten Sims Hubicki Associates (2000) Southdown District Master Drainage Plan, report prepared for City of Mississauga.

3 Environmental Water Resources Group Ltd. (1996) Birchwood Creek Drainage Study, final report prepared for City of Mississauga.

4 Aquafor Beech Ltd. (2003) Floodline Mapping Study: Serson, Cawthra, Stavebank, and Lakeside Creek, report prepared for Credit Valley Conservation and City of Mississauga.

5 McCormick Rankin Corporation in Association with Ecoplans Limited (2007) Clearview Subwatershed Study, Final Report, Prepared for Park Mount Holdings (Oakville).

6 R.V. Anderson Associates Limited. (1996) Cooksville Creek Floodline Mapping Study, report for the City of Mississauga. 7 Golder Associates Ltd. (2005) Credit River Floodline Mapping Study, report prepared for Credit Valley Conservation and

City of Mississauga.

8 Credit Valley Conservation (2009) Sheridan Creek Watershed Study and Impact Monitoring, Characterization Report, Draft. 9 Aquafor Beech Ltd. (2005) Floodline Mapping Study: Sawmill, Carolyn and Tecumseh Creeks, report prepared for Credit

Valley Conservation and City of Mississauga. Aquafor Beech Ltd. (2002) Turtle Creek Floodline Mapping Study, report prepared for Credit Valley Conservation and City of Mississauga.



Table 3.6: Summary of Hydraulic Modelling by Subwatershed Watershed Developer Year

Developed Name of Model


Applewood Creek1

Philips 2003 HEC-RAS - -

Avonhead Creek2

TSH 2000 HEC-2 & HEC-RAS

- -

Birchwood Creek3

EWRG 1996 HEC-2 1. Water surface elevations calculated assumed that the crossing embankments have failed (conservative).

2. Water levels were calculated taking into account the maximum water level from upstream reservoir routing or assuming crossings had not been constructed.

Cawthra Creek4

Aquafor 2003 HEC-RAS 1. Overland flow between buildings was assumed to be negligible relative to the overall flow through the cross sections, and there, the cross-sections did not extend past the first row of buildings.

2. No historic water level data was available and therefore, the calibration of the hydraulic model was not undertaken.

-

Clearview Creek2,5

MRC 2005 HEC-2 & HEC-RAS

- -

Cooksville Creek6

EWRG 2002 HEC-2 1. Water levels are not recorded in the Cooksville creek watershed and therefore the model was not

-




Name of Model


calibrated. Credit River7 Golder 2005 HEC-RAS - - Cumberland

Creek - - -

- -

Lakeside Creek4



-

Lornewood Creek1

Philips 2003 HEC-RAS - -

Moore Creek - - - - - Serson Creek4 Aquafor 2003 HEC-RAS 1. Overland flow between buildings was

assumed to be negligible relative to the overall flow through the cross sections, and there, the cross-sections did not extend past the first row of buildings.


-

Sheridan Creek8

Winter 2000 HEC-RAS

1. Water levels are not recorded within Sheridan Creek; therefore, a detailed calibration of the hydraulic model was not possible.

-




Name of Model


Tecumseh Creek9



1. Standard values recommended by the CVC were used to estimate Manning’s roughness coefficients and initial abstraction/depression storage. These coefficients are based on vegetation observed during field investigations.

2. The starting water surface elevation for the model was set at the mean annual Lake Ontario water level (74.8 m) as recommended by CVC’s standard modelling parameters.

3. Manning’s roughness coefficients for the culvert structures were selected from CVC’s standard values recommended for use with concrete and corrugated steel pipes.

Turtle Creek10

Aquafor 2002 HEC-RAS 1. No historic water level data was available and therefore, the calibration of the hydraulic model was not undertaken.

-

Aquafor – Aquafor Beech Ltd. EWRG – Environmental Water Resources Group Golder – Golder Associates MRC – McCormick Rankin Corp. Philips – Philips Engineering Ltd. TSH – Totten Sims Hubicki Associates Winter – Winter Environmental Consulting (Note: Winter Environmental Consulting (2000) Sheridan Creek Flood Line Mapping Study not provided for LOISS but reference in CVC (2009) Sheridan Creek Watershed Study and Impact Monitoring.) 1 Philips Engineering Ltd. (2001) Applewood, Lornewood and Wolfedale Creeks: Hydrologic Modelling Assessment, report

prepared for Credit Valley Conservation and City of Mississauga. 2 Totten Sims Hubicki Associates (2000) Southdown District Master Drainage Plan, report prepared for City of

Mississauga. 3 Environmental Water Resources Group Ltd. (1996) Birchwood Creek Drainage Study, final report prepared for City of




Name of Model


Mississauga. 4 Aquafor Beech Ltd. (2003) Floodline Mapping Study: Serson, Cawthra, Stavebank, and Lakeside Creek, report prepared

for Credit Valley Conservation and City of Mississauga. 5 McCormick Rankin Corporation in Association with Ecoplans Limited (2007) Clearview Subwatershed Study, Final

Report, Prepared for Park Mount Holdings (Oakville). 6 R.V. Anderson Associates Limited. (1996) Cooksville Creek Floodline Mapping Study, report for the City of Mississauga. 7 Golder Associates Ltd. (2005) Credit River Floodline Mapping Study, report prepared for Credit Valley Conservation and


8 Credit Valley Conservation (2009) Sheridan Creek Watershed Study and Impact Monitoring, Characterization Report, Draft. 9 Aquafor Beech Ltd. (2005) Floodline Mapping Study: Sawmill, Carolyn and Tecumseh Creeks, report prepared for Credit

Valley Conservation and City of Mississauga. 10 Aquafor Beech Ltd. (2002) Turtle Creek Floodline Mapping Study, report prepared for Credit Valley Conservation and




The availability of gauging stations on the watercourses found within the Study Area was next investigated. CVC has installed and maintains impact monitoring stations that are regulated under CVC’s Integrated Watershed Monitoring Program (IWMP). There are a total of three impact monitoring stations regulated by the CVC within the Study Area (CA-1, CO-1b, and SH-2). CA-1 is found in the Cawthra Creek watershed and is located at the corner of Atwater Avenue and Cawthra Road. CO-1b is found in the Cooksville Creek watershed and is located at the corner of Lakeshore Road East and Beechwood Avenue. SH-2 is found in the Sheridan Creek watershed and is located near the Rattray Marsh. It is important to note that the monitoring stations CO-1B and CA-1 were monitored between 2007 and 2009 but were discontinued in 2011 due to a shortage of funding. Presently, only temperature is measured at CO-1B station. The Water Survey of Canada gauging station on the Credit River closest to the Study Area is located in Streetsville, more than 15 km upstream of the outlet of the river into Lake Ontario. The period of record at this station is limited as it begins in 2006. There is also a Water Survey of Canada gauging station on Cooksville Creek at Central Parkway East; however, this station is more than 6 km from the mouth of the creek at Lake Ontario and the period of record is again limited as it begins in 2006. There are no Water Survey of Canada gauging stations on the other watercourses included in the study. Thus, insufficient data or a lack of gauging stations makes the use of frequency analysis unsuitable for the determination of return period flows. Instead, the return period flows for the watercourses in the Study Area were compiled from the documentation provided and are summarized in Table 3.7. Where available, values have been given at multiple locations within the Study Area. Values for Cumberland Creek were not available in the material provided. Additionally, values for return periods less than 50-years were not available for Avonhead and Clearview Creeks nor were Regional flows available for all locations on the Credit River.



Table 3.7: Summary of Return Period Flows by Subwatershed Flow (m3/s) Watercourse Location

2-year 5-year 10-year 25-year 50-year 100-year Regional QEW 12.64 18.32 24.66 30.25 35.41 40.68 39.65 CNR 10.04 14.08 18.70 22.87 29.69 30.90 45.98

Applewood Creek1

Lake Ontario (Outlet) 9.57 13.77 18.48 22.72 26.77 31.31 50.20 North of Lakeshore Road – Existing - - - - 15.67 28.20 28.82

Avonhead Creek2 Western portion of watershed – Post-

development - - - - 2.84 3.24 3.80

Lakeshore Road West (existing(1996)/future)

6.7/8.9 8.2/11 9.5/12 12/15 14/18 16/20 32/33 Birchwood Creek3

Lake Ontario 6.7/8.9 8.2/11 9.5/12 12/15 14/18 16/20 35/35 Flow into Cooksville Creek diversion at

Delwood Park 10.6 17.4 24.8 31.2 36.9 44.4 51.2

Cawthra Creek4 Overland flow into remnant channel

south of Lakeshore Road 0.0 0.0 0.0 7.2 14.0 22.1 30.5

North of Lakeshore Road – Existing - - - - 19.69 25.05 36.01 North of Lakeshore Road – Post-

development (includes runoff from Avonhead)

- - - - 22.59 28.43 36.32

South of Lakeshore Road – Post-development (includes runoff from

Avonhead) - - - - 40.13 48.61 55.63

Chicago 24 hr Distribution2, 10 Subcatchment 401 (Clearview Community), South of Sheridan Garden Drive

2.12 3.71 5.18 6.50 9.34 12.27 -

Subcatchment 402, between CNR & Winston Churchill Blvd.

4.16 5.96 7.58 8.95 11.07 12.58 -

Clearview Creek2,10

Winston Churchill Blvd. 5.65 7.61 9.37 10.98 13.89 17.54 -



Flow (m3/s) Watercourse Location 2-year 5-year 10-year 25-year 50-year 100-year Regional

SCS Distribution2, 10

Subcatchment 401 (Clearview Community), South of Sheridan Garden

Drive - - - - 11.65 13.82 20.53

Subcatchment 402, between CNR & Winston Churchill Blvd.

- - - - 7.46 8.67 9.95

Winston Churchill Blvd. - - - - 16.55 19.80 29.29 4 – hr Chicago Distribution10

Subcatchment 1 (includes the Clearview Community)

2.34 3.91 5.08 7.13 9.35 11.51 -

Subcatchment 2, CNR to Royal Windsor Drive

2.47 4.12 5.33 7.46 9.79 12.05 -

Subcatchment 3, Royal Windsor Drive to Beryl Road

3.88 5.77 7.06 8.87 10.46 12.89 -

Subcatchment 4, Beryl Road to CNR Spur Line

5.11 7.55 9.23 11.57 13.25 14.91 -

Subcatchment 5, CNR Spur Line to Winston Churchill Blvd.

5.14 7.58 9.26 11.61 13.29 14.96 -

Upstream of Eglinton 116.1 208.48 265.29 355.9 424.71 492.63 732.6 Upstream of Highway 5 122.61 227.23 288.57 374.56 466 539.42 - Upstream of QEW 124.55 227.98 290.02 390.38 470.85 542.83 -

Credit River6

CNR 126 231.22 293.51 395.31 477.57 550.24 - Cumberland

Creek - - - - - - -

Lakeside Creek4 Lake Ontario (Outlet) 1.8 3.3 5.0 6.7 8.3 10.1 13.3




Lornewood Creek1 QEW 3.60 5.08 6.48 7.69 10.35 11.77 12.03

Moore Creek - - - - - - - CNR Line 3.1 5.3 8.0 10.2 12.6 15.4 18.3

Serson Creek4

Lake Ontario (Outlet) 4.1 6.7 9.8 12.4 14.9 18.2 23.4 Stavebank

Creek4 Outlet to Credit River 0.8 1.5 2.2 2.8 3.5 4.3 4.5

Lakeshore Road 27.74 41.05 45.09 61.98 71.25 80.46 86.76 Clarkson Road 27.37 41.05 45.21 62.77 72.68 82.21 94.27

Meadow Wood Road 27.65 41.60 46.13 64.49 74.79 84.80 97.65 Sheridan Creek7

Lake Ontario 27.78 43.17 47.23 66.88 78.08 89.12 108.02 CNR Line – Unattenuated 2.5 4.4 6.6 8.7 10.5 12.5 16.2 Tecumseh

Creek8 Lake Ontario (Outlet) 3.1 5.5 8.0 10.7 12.8 15.1 19.1 Outlet of STM at Hydro ROW 4.7 7.0 9.7 12.1 13.9 16.8 10.2

CNR Line 6.0 9.0 12.3 15.0 17.3 20.3 14.5

Lakeshore Road 5.4 8.1 11.1 14.0 16.5 19.6 18.8

Turtle Creek9

Lake Ontario (Outlet)

4.2 6.3 9.0 11.5 14.0 17.0 25.5 1 Philips Engineering Ltd. (2001) Applewood, Lornewood and Wolfedale Creeks: Hydrologic Modelling Assessment,

report prepared for Credit Valley Conservation and City of Mississauga. 2 Totten Sims Hubicki Associates (2000) Southdown District Master Drainage Plan, report prepared for City of

Mississauga. 3 Environmental Water Resources Group Ltd. (1996) Birchwood Creek Drainage Study, final report prepared for City

of Mississauga. 4 Aquafor Beech Ltd. (2003) Floodline Mapping Study: Serson, Cawthra, Stavebank, and Lakeside Creek, report

prepared for Credit Valley Conservation and City of Mississauga. 5 R.V. Anderson Associates Limited. (1996) Cooksville Creek Floodline Mapping Study, report for the City of

Mississauga. 6 Golder Associates Ltd. (2005) Credit River Floodline Mapping Study, report prepared for Credit Valley

Conservation and City of Mississauga.




7 Credit Valley Conservation (2009) Sheridan Creek Watershed Study and Impact Monitoring, Characterization Report, Draft. 8 Aquafor Beech Ltd. (2005) Floodline Mapping Study: Sawmill, Carolyn and Tecumseh Creeks, report prepared for

Credit Valley Conservation and City of Mississauga. 9 Aquafor Beech Ltd. (2002) Turtle Creek Floodline Mapping Study, report prepared for Credit Valley Conservation

and City of Mississauga. 10 McCormick Rankin Corporation in Association with Ecoplans Limited (2007) Clearview Subwatershed Study, Final

Report, Prepared for Park Mount Holdings (Oakville).



Through the review of the available flood studies, a list of the structures overtopped within the Study Area and the return period at which they first overtop was compiled. This list is provided by watercourse in Table 3.8.



Table 3.8: Overtopped Structures Watercourse Structure Return Period at which

Structure is Overtopped Lakeshore Road East 50-year

St. James Avenue 10-year St. Marys Avenue 10-year

Trailer bridge 5-year

Applewood Creek1

CNR bridge 100-year Avonhead Creek2 - -

Lakeshore Road Regional Birchwood Creek3

Birchwood Drive Regional Cawthra Creek4 Diversion to Cooksville Creek

upstream of Atwater Avenue 10-year

North of Royal Windsor Drive >100 Year Royal Windsor Drive >100 Year

CNR Spur Line >10 Year

Clearview Creek10

Winston Churchill Blvd >100 Year < Regional Lakeshore Road East 50-year

Private Access 2-year CNR Regional

Atwater Avenue 10-year

Cooksville Creek5

QEW 5-year Old Derry Road Regional

The Private Bridge Regional Reid’s Dam Regional

Barbertown Road Regional

Credit River6

Creditview Road Regional Cumberland Creek - - Lakeside Creek4 Pedestrian Walkway 5-year

Lornewood Creek1 Lakeshore Road West Regional Moore Creek - -

Clarkson Road (Upstream of Inverhouse Drive & South

Sheridan way)

Regional

Bonner Road Regional Benedet Drive Regional

Sheridan Creek7

Public Trail Regional Railway Spur – Lakeview Sewage Treatment Plant

5-year

Lakeshore Road East 100-year Hydro Access Road 2-year

CNR Spur Line 50-year CNR Main Line 25-year

Fourth Street 5-year

Serson Creek4

Pelham Avenue 5-year



Watercourse Structure Return Period at which Structure is Overtopped

Serson Avenue 10-year Atwater Avenue 2-year

Tecumseh Creek8 No Structures Flooded Bexhill Road 50-year

Lakeshore Road 10-year Private Driveway 5-year

CNR/Hindhead Park 5-year

Turtle Creek9

Hindhead Road 2-year 1 Philips Engineering Ltd. (2001) Applewood, Lornewood and Wolfedale

Creeks: Hydrologic Modelling Assessment, report prepared for Credit Valley Conservation and City of Mississauga.

2 Totten Sims Hubicki Associates (2000) Southdown District Master Drainage Plan, report prepared for City of Mississauga.

3 Environmental Water Resources Group Ltd. (1996) Birchwood Creek Drainage Study, final report prepared for City of Mississauga.

4 Aquafor Beech Ltd. (2003) Floodline Mapping Study: Serson, Cawthra, Stavebank, and Lakeside Creek, report prepared for Credit Valley Conservation and City of Mississauga.

5 R.V. Anderson Associates Limited. (1996) Cooksville Creek Floodline Mapping Study, report for the City of Mississauga.

6 Golder Associates Ltd. (2005) Credit River Floodline Mapping Study, report prepared for Credit Valley Conservation and City of Mississauga.

7 Credit Valley Conservation (2009) Sheridan Creek Watershed Study and Impact Monitoring, Characterization Report, Draft.

8 Aquafor Beech Ltd. (2005) Floodline Mapping Study: Sawmill, Carolyn and Tecumseh Creeks, report prepared for Credit Valley Conservation and City of Mississauga.

9 Aquafor Beech Ltd. (2002) Turtle Creek Floodline Mapping Study, report prepared for Credit Valley Conservation and City of Mississauga.

10 McCormick Rankin Corporation in Association with Ecoplans Limited (2007) Clearview Subwatershed Study, Final Report, Prepared for Park Mount Holdings (Oakville).

For the following watersheds, information regarding overtopped structures is unavailable or insufficient:

• Avonhead Creek, • Cumberland Creek, and • Moore Creek.

A summary of the number of buildings flooded within the Study Area for the 2-year to Regional storm events is provided by watercourse in Table 3.9. Where data are unavailable, the entry has



been filled with a dash (-). A summary of the total number of buildings flooded under the Regulatory event for the entire extent of each watershed is presented in Table 3.10. Table 3.9: Flooded Buildings within the Study Area

Number of Buildings Flooded by Return Period Watercourse Regional 100-Year 50-Year 25-Year 10-Year 5-Year 2-Year

Applewood Creek

17 - - - - - -

Avonhead Creek Birchwood

Creek 5 1 0 0 0 0 0

Cawthra Creek 5 5 5 5 5 0 0 Clearview Creek Cooksville Creek 133 39 25 17 13 5 0

Credit River 0 0 0 0 0 0 0 Cumberland

Creek

Lakeside Creek 0 0 0 0 0 0 0 Lornewood

Creek 10 - - - - - -

Moore Creek Serson Creek 106 106 106 106 86 6 1

Sheridan Creek Tecumseh Creek 8 0 0 0 0 0 0

Turtle Creek 58 58 58 58 56 56 4 Table 3.10: Flooded Building within Entire Watersheds

Number of Buildings Flooded Watercourse Total*

Applewood Creek 20 Avonhead Creek 11 Birchwood Creek 5 Cawthra Creek 3 Clearview Creek 1 Cooksville Creek 309* Credit River - Cumberland Creek - Lakeside Creek 0 Lornewood Creek 11 Moore Creek - Serson Creek 154 Sheridan Creek 8* Tecumseh Creek 2 Turtle Creek 79



*NOTE: The total number was taken from the report as compared to the rest, which were manually counted from the floodline maps. For the following watersheds, information regarding flooded buildings is unavailable or insufficient:

• Avonhead Creek, • Clearview Creek, • Cumberland Creek, and • Sheridan Creek.

4 CONCLUSIONS

For the most part, the information required for the hydrology and hydraulics component of the study was found within the documentation provided. Missing information has been summarized in section 5.

5 DATA GAPS

The key findings of the hydrology and hydraulics component of the study were the return period flows, the lists overtopped structures and flooded building, the watershed characteristics, and the availability of hydrologic and hydraulic modelling on a watershed basis. After reviewing the available floodline studies for the subject area, the data gaps were identified. These data gaps are summarized in Table 5.1 and Table 5.2 below. Table 5.1: Summary of Missising Flow Data Watercourse Location Missing Flows

North of Lakeshore Road – Existing 2- to 25-year Avonhead

Creek Western portion of watershed – Post-development

2- to 25-year

Upstream of Highway 5 Regional Upstream of QEW Regional Credit River

CNR Regional Cumberland

Creek All All

Moore Creek All Alla Table 5.2: Summary of Additional Missing Data List of overtopped structures and flooded buildings

• Avonhead Creek • Cumberland Creek • Moore Creek

Imperviousness (%) • Clearview Creek • Credit River • Cumberland Creek • Moore Creek



• Sheridan Creek Drainage area • Cumberland Creek

• Moore Creek Hydrologic model • Cumberland Creek

• Moore Creek Hydraulic model • Cumberland Creek

• Moore Creek Flood hazard mapping • Cumberland Creek

• Moore Creek One other shortcoming in the Hydrology and Hydraulic portion of the LOISS is the precipitation record. The record is less than 15 years in length and contains many gaps. Additionally, of the two gauges within the Study Area, Station 1 and Station 2, only Station 2 was a heated gauge. The Station 1 data set was too full of errors to be of use. To remedy the issues associated with the precipitation record, it is recommended that monitoring of precipitation be continued to increase the length of the record and that the gauges be maintained regularly to prevent data gaps. As well, it may be beneficial to replace the gauge at Station 1 with a heated gauge.

Documents

LOISS Background Report APP A Hydrology and Hydraulics · 2012-03-01 · Hydrology and Hydraulics Report Lake Ontario Integrated Shoreline Strategy Aquafor Beech Limited 1 1 INTRODUCTION