FLOOD04285

• Designation Number: 270
• County: Adams
• Community: Westminster
• Stream Name: Big Dry Creek & Tributaries
• Basin: South Platte
• Title: Flood Hazard Area Delineation - Big Dry Creek & Tributaries
• Date: 11/1/1986
• Designation Date: 12/1/1987
• Floodplain - Doc Type: Floodplain Report/Masterplan

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TABLE 6
SUB-BASIN PARAMETERS FOR BIG DRY CREEK ANALYSIS

Developed Loss Ra tes
Drainage Length Ia Ia
Sub-Basin Area L Lca % Impervious % Impervious * Ct Pervious Impervious Ini tia 1 Fina 1
Flooding Source Designation (Sq.Mi.) (Mi) (Mi) Exis ting Deve loped Prog. Cp Retention Retention in/hr in/hr Decay Rate Comments
Big Dry Creek 075 16.75 11.23 4.76 19.23 23.00 0.49 0.52 0.4 0.1 3.1 0.51 0.0018
072 1.76 1.52 1.04 23.00 41. 20 0.24 0.58 0.4 0.1 3.6 0.54 .0018
069 0.39 1.86 0.76 10.80 54.30 0.23 0.57 0.4 0.1 3.0 0.50 .0018
068 0.15 1.14 0.43 41.50 52.70 0.19 0.49 0.3 0.1 3.0 0.50 .0018
063 1.80 2.58 1.14 22.70 39.00 0.32 0.55 0.1 3.4 0.53 .0018
061 0.53 1.62 1.14 22.10 54.30 0.23 0.60 0.4 0.1 3.6 0.54 .0018
057 0.37 1.24 0.60 50.00 68.00 0.21 0.64 0.4 0.1 3.0 0.50 .0018
051 0.21 1.14 0.71 5.00 47.70 0.26 0.48 0.4 0.1 3.0 0.50 .0018
046 0.44 1.43 0.86 22.30 50.50 0.24 0.55 0.4 0.1 3.3 0.52 .0018
040 0.04 0.19 0.19 5.00 32.50 0.15 0.26 0.4 0.1 3.0 0.50 .00l8
022 0.26 1.71 0.38 12.30 45.80 0.24 0.48 0.4 0.1 3.2 0.51 .0018
016 2.85 2.86 1.52 8.00 50.80 0.29 0.74 0.4 0.1 3.3 0.52 .00l8
010 0.78 1.67 0.67 6.00 46.50 0.27 0.57 0.4 0.1 3.1 0.51 .00l8
004 2.42 3.33 1.52 31.40 64.60 0.31 0.83 0.4 0.1 3.0 0.50 .00l8
Quail Creek 970 3.08 4.10 2.33 15.70 31. 90 0.44 0.50 0.4 0.1 3.1 0.51 .00l8
Wes t Lake 907 Hydr graphs 0 tained rom Referenc 13
Nissen Res. 913 Hydrographs Obtained From Reference 13
Brandywine 980 0.42 1.47 0.76 12.60 47.20 0.26 0.52 0.4 0.1 3.1 0.51 .OOl8
Tang1ewood-Creek 101 1.12 2.24 1.33 28.70 62.90 0.25 0.73 0.4 0.1 3.4 0.53 .00l8 includes 102
102 0.11 0.48 0.24 27.30 46.80 0.14 0.43 0.4 0.1 3.0 0.50 .00l8
North Cotton Cr. 320 0.10 0.48 0.19 5.00 41. 30 0.14 0.34 0.4 0.1 4.1 0.57 .00l8
319 0.14 0.96 0.40 5.00 49.00 0.17 0.46 0.4 0.1 4.1 0.57 .00l8
Middle Cotton Cr. 326 0.10 0.57 0.38 20.20 37.80 0.15 0.35 0.3 0.1 3.6 0.54 .00l8
325 0.32 1.57 0.95 22.70 39.40 0.22 0.43 0.4 0.1 3.4 0.53 .00l8 includes 326
Sou th Cotton Cr. 332 0.10 0.57 0.33 5.00 46.30 0.15 0.42 0.4 0.1 3.4 0.53 .0018
331 0.19 1.09 0.48 8.40 52.20 0.26 0.50 0.4 0.1 3.4 0.53 .00l8 includes 332
Airport Creek 740 0.43 1.52 0.71 48.90 48.90 0.23 0.54 0.3 0.1 3.0 0.50 .00l8
739 0.79 2.16 1.19 20.00 52.30 0.29 0.67 0.4 0.1 3.4 0.53 .0018
737 1.29 2.33 1.00 36.40 67.30 0.24 0.72 0.4 0.1 3.3 0.52 .00l8 includes 740
N. Airport Creek 742 0.03 0.38 0.17 28.30 28.30 0.16 0.23 0.4 0.1 3.0 0.50 .00l8
741 0.27 1.28 0.57 23.40 24.40 0.23 0.29 0.4 0.1 3.4 0.53 .00l8 includes 742
N. City Park Cr. 344 0.10 0.48 0.19 5.00 41.30 0.14 0.34 0.4 0.1 4.1 0.57 .0018
343 0.14 0.96 0.40 5.00 49.00 0.17 0.46 0.4 0.1 4.1 0.57 .00l8 includes 344
S. Ci ty Park Cr. 350 0.02 0.24 0.12 5.00 68.00 0.09 0.41 0.4 0.1 3.7 0.55 .00l8
349 0.09 0.72 0.38 5.50 31.00 0.17 0.28 0.4 0.1 3.7 0.55 .00l8 includes 350

* Ct adjusted for CUHP-D computer program for application of the 1982 version of the Colorado Urban Hydrograph Procedure.

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