Thompson Creek Flood Study Report - City of Peterborough

Thompson Creek Detailed Flood Reduction Study
City of Peterborough
Future Land Use
Once the existing conditions model had been verified, the Thompson Creek watershed
was further subdivided as shown in Figure 4.4.2, to allow for an accurate representation
of future conditions. The model computes flows at the same locations in the creek but
uses additional detail to fully represent the changed land use conditions. Table 4.4.2
shows the parameters used in this version of the model. It should be noted that based
upon the results of the “Thompson Creek Central Stormwater Management Facility
Class EA, Environmental Study Report,” it was assumed that the northern boundary of
Thompson Creek would remain as in the existing conditions model. This is because
that report recommended diversion of all flows from the proposed development north of
Thompson Creek to a central stormwater management facility adjacent to the Otonabee
River. Since the area is currently occupied by a former quarry, its elevation is below
the creek and currently no storm runoff from the area enters Thompson Creek. Hence
the proposed stormwater management approach will maintain this situation.
Documentation of the future conditions model is included in Appendix H.
Table 4.4.1
Visual OTTHYMO Model Parameters for Existing Conditions
Parameter Sub-Catchment
10
Sub-Catchment
11
Sub-Catchment
12
Sub-Catchment
13
OTTHYMO NASHYD STANDHYD STANDHYD STANDHYD
Command
Drainage Area 15.8 18.5 11.5 18.1
(ha)
CN 54 69 69 69
IA (mm) 6 4 4 4
N 3
TP (hr) 0.374
XIMP 0.20 0.20 0.17
TIMP 0.26 0.26 0.22
SLPP (%) 2 2 2
LGP (m) 40 40 40
MNP 0.03 0.03 0.03
DPSI (mm) 0.5 0.5 0.5
SLPI (%) 1 1 1
LGI (m) 351.2 276.9 347.4
MNI 0.013 0.013 0.013
Abbreviations: CN – SCS Curve Number, IA – Initial Abstraction, N – NASHYD No. of linear
reservoirs, TP – Time to Peak, XIMP – Directly Connected Imperviousness, TIMP – Total
Imperviousness, SLPP – Slope of Pervious Area, LGP – Length of Pervious Area, MNP – Manning’s
roughness of Pervious Area, DPSI – Depression Storage of Impervious Area, SLPI – Slope of
Impervious Area, LGI – Length of Impervious Area, MNI – Manning’s roughness of Impervious
Area.
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