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Appendix D - Flood Assessment
Attached to the e-mail RAL20/0014 - Response to Council's Information Request - 9A Jirrima Cres, Cooroibah - Email 02 of 02.
Components of time of concentration
(i) Estimate length of sheet runoff as per Table 4.06.3 and calculate travel time using Friends Equation (as per 4.06.6)
(ii) Kerb flow time (if applicable)
(iii) Pipe flow time
(iv) Creek and/or channel flow time
(i) Overland Flow (Section 4.06.6-Friends)
Notes: (1) Refer to Table 4.06.3 for estimated length of sheet flow
(2) Refer to Table 1 for Hortons roughness values
Catchment Cat_1 Cat_2 Cat_3 Cat_4 Cat_5 Cat_6 Cat_7 Cat_8 Cat_9 Cat_10 Cat_11 Cat_12 Cat_13
Estimated Length of Sheet Flow (Table 4.06.3) 100 100 100 100 100 100 100 100 100 100 100 100 100
Hortons Roughness Value 0.045 0.045 0.045 0.045 0.045 0.045 0.06 0.045 0.06 0.045 0.045 0.045 0.06
Slope (%) 6 5 5 3 8 4 2 4 2 6 4 6 1
tc (minutes) 15.59 16.17 16.17 17.91 14.72 16.91 25.90 16.91 25.90 15.59 16.91 15.59 29.75 0.00
(iv) Channel/Creek Flow
Note: Determine actual flow velocity from numerical modelling or the Manning Equation. Alternatively, if the expected travel time in the creek is not critical, assume an avergae flow velocity of
1.5m/s (not applicable to constructed channels)
Catchment Cat_1 Cat_2 Cat_3 Cat_4 Cat_5 Cat_6 Cat_7 Cat_8 Cat_9 Cat_10 Cat_11 Cat_12 Cat_13
Length of Channel Flow (m) 97 200 100 60 83 50 63 263 82 191 84 70 20
Velocity (m/s) - refer to Note 1.5 0.9 1.5 0.9 0.9 0.9 0.3 0.7 0.7 0.7 0.7 0.9 0.3 0.9
tc (minutes) 1.08 3.70 1.11 1.11 1.54 0.93 3.50 6.26 1.95 4.55 2.00 1.30 1.11 0.00
Catchment Cat_1 Cat_2 Cat_3 Cat_4 Cat_5 Cat_6 Cat_7 Cat_8 Cat_9 Cat_10 Cat_11 Cat_12 Cat_13
TOTAL tc (minutes) 16.67 19.88 17.28 19.02 16.26 17.84 29.40 23.17 27.85 20.14 18.91 16.89 30.86 0.00
Catchment Details
Pre
Cat_1 Cat_2 Cat_3 Cat_4 Cat_5 Cat_6 Cat_7 Cat_8 Cat_9 Cat_10 Cat_11 Cat_12 Cat_13
Development
Area (ha) 3.355 3.779 1.716 1.483 1.137 0.63 1.62 3.43 1.56 3.43 1.86 1.69 0.76
Pre Development Flows
Catchment Area tc I100 C100 Q100 I50 C50 Q50 I20 C20 Q20 I10 C10 Q10 I5 C5 Q5 I2 C2 Q2 I1 C1 Q1
Name (ha) (min) (mm/hr) (m³/s) (mm/hr) (m³/s) (mm/hr) (m³/s) (mm/hr) (m³/s) (mm/hr) (m³/s) (mm/hr) (m³/s) (mm/hr) (m³/s)
Cat_1 3.36 16.67 204.31 0.84 1.60 186.97 0.81 1.40 162.98 0.74 1.12 143.65 0.70 0.94 125.31 0.67 0.78 101.39 0.60 0.56 80.62 0.56 0.42
Cat_2 3.78 19.88 187.64 0.84 1.65 171.59 0.81 1.45 149.52 0.74 1.15 131.47 0.70 0.97 114.42 0.67 0.80 92.54 0.60 0.58 73.76 0.56 0.43
Cat_3 1.72 17.28 201.12 0.84 0.81 184.03 0.81 0.71 160.40 0.74 0.56 141.32 0.70 0.47 123.23 0.67 0.39 99.69 0.60 0.28 79.31 0.56 0.21
Cat_4 1.48 19.02 192.07 0.84 0.66 175.68 0.81 0.58 153.10 0.74 0.46 134.71 0.70 0.39 117.32 0.67 0.32 94.89 0.60 0.23 75.59 0.56 0.17
Cat_5 1.14 16.26 206.45 0.84 0.55 188.95 0.81 0.48 164.71 0.74 0.38 145.21 0.70 0.32 126.72 0.67 0.27 102.52 0.60 0.19 81.50 0.56 0.14
Cat_6 0.63 17.84 198.24 0.84 0.29 181.38 0.81 0.25 158.08 0.74 0.20 139.22 0.70 0.17 121.35 0.67 0.14 98.17 0.60 0.10 78.13 0.56 0.08
Cat_7 1.62 29.40 156.68 0.84 0.59 141.68 0.81 0.51 122.44 0.74 0.41 107.32 0.70 0.34 93.81 0.67 0.28 75.43 0.60 0.20 60.13 0.56 0.15
Cat_8 3.43 23.17 175.58 0.84 1.41 160.21 0.81 1.23 138.84 0.74 0.97 122.11 0.70 0.82 106.38 0.67 0.67 85.92 0.60 0.49 68.42 0.56 0.37
Cat_9 1.56 27.85 161.01 0.84 0.58 146.01 0.81 0.51 126.15 0.74 0.40 110.72 0.70 0.34 96.69 0.67 0.28 77.85 0.60 0.20 62.02 0.56 0.15
Cat_10 3.43 20.14 186.49 0.84 1.49 170.52 0.81 1.31 148.55 0.74 1.04 130.60 0.70 0.87 113.66 0.67 0.72 91.92 0.60 0.52 73.27 0.56 0.39
Cat_11 1.86 18.91 192.66 0.84 0.84 176.22 0.81 0.73 153.57 0.74 0.58 135.14 0.70 0.49 117.70 0.67 0.41 95.20 0.60 0.29 75.83 0.56 0.22
Cat_12 1.69 16.89 203.17 0.84 0.80 185.93 0.81 0.70 162.06 0.74 0.56 142.82 0.70 0.47 124.57 0.67 0.39 100.78 0.60 0.28 80.15 0.56 0.21
Cat_13 0.76 30.86 153.33 0.84 0.27 138.50 0.81 0.23 119.66 0.74 0.18 104.81 0.70 0.15 91.62 0.67 0.13 73.61 0.60 0.09 58.69 0.56 0.07
[OCR of page images]
Components of time of concentration
(i) Estimate length of sheet runoff as per Table 4.06.3 and calculate travel time using Friends Equation (as per 4.06.6)
(ii) Kerb flow time (if applicable)
(iii) Pipe flow time
(iv) Creek and/or channel flow time
(i) Overland Flow (Section 4.06.6-Friends)
Notes: (1) Refer to Table 4.06.3 for estimated length of sheet flow
(2) Refer to Table 1 for Hortons roughness values
Catchment Cat_1 Cat_2 Cat_3 Cat_4 Cat_5 | Cat | Cat? | Cat8 | Cat_9 | Cat_10 | Cat_11 | Cat_1z2 | Cat_13
Estimated Length of Sheet Flow (Table 4.06.3) 100 100 100 100 100 100 100 100 100 100 100 100 100
Hortons Roughness Value 0.045 0.045 0.045 0.045 0.045 0.045 0.06 0.045 0.06 0.045 0.045 0.045 0.06
Slope (%) 6 5 5 3 8 4 2 4 2 6 4 6 1
tc (minutes) 15.59 16.17 16.17 17.91 14.72 16.91 25.90 16.91 25.90 15.59 16.91 15.59 29.75 0.00
(iv) Channel/Creek Flow
Note: Determine actual flow velocity from numerical modelling or the Manning Equation. Alternatively, if the expected travel time in the creek is not critical, assume an avergae flow velocity of
1.5m/s (not applicable to constructed channels)
Catchment Cat_1 Cat_2 Cat_3 Cat_4 Cat_5 | Cat | Cat? | Cat8 | Cat_9 | Cat_10 | Cat_41 | Cat_12 | Cat_13
Length of Channel Flow (m) 97 200 100 60 83 50 63 263 82 191 84 70 20
Velocity (m/s) - refer to Note 1.5 0.9 1.5 0.9 0.9 0.9 0.3 0.7 0.7 0.7 0.7 0.9 0.3 0.9
tc (minutes) 1.08 3.70 1.11 1.11 1.54 0.93 3.50 6.26 1.95 4.55 2.00 1.30 1.11 0.00
Catchment Cat_1 Cat_2 Cat_3 Cat_4 Cat_5 Cat_6 Cat_7 Cat_8 Cat_9 | Cat_10 | Cat_11 | Cat_12 | Cat_13
TOTAL tc (minutes) 16.67 19.88 17.28 19.02 16.26 17.84 29.40 23.17 27.85 20.14 18.91 16.89 30.86 0.00
Catchment Details
nee) Cat_1 Cat_2 Cat_3 Cat_4 Cat_s Cat_é Cat_7 Cat_8 Cat_9 Cat_10 Cat_11 Cat_12 Cat_13
Development = ~ = = - s ~ S = - = -
Area (ha) 3.355 3.779 1.716 1.483 1.137 0.63 1.62 3.43 1.56 3.43 1.86 1.69 0.76
Pre Development Flows
Catchment ‘Area te Tico Cro Qi00 Teo Ceo 50 bo Can Q20 To Cio aio 5 Cs a5 bE CG a2 T Cr at
Name (ha) (min) (mm/hr) (m/s) (mm/hr) (m/s) (mm/hr) (m/s) (mm/hr) (m/s) (mm/hr) (m/s) (mm/hr) (m/s) (mm/hr) (m/s)
Cat_i 3.36 16.67 204.31 0.84 1.60 186.97 0.81 1.40 162.98 0.74 1.12 143.65 0.70 0.94 125.31 0.67 0.78 101.39 0.60 0.56 80.62 0.56 0.42
Cat_2 3.78 19.88 187.64 0.84 1.65 171.59 0.81 1.45 149.52 0.74 1.15 131.47 0.70 0.97 114.42 0.67 0.80 92.54 0.60 0.58 73.76 0.56 0.43
Cat_3 1.72 17.28 201.12 0.84 0.81 184.03 0.81 0.71 160.40 0.74 0.56 141.32 0.70 0.47 123.23 0.67 0.39 99.69 0.60 0.28 79.31 0.56 0.21
Cat_4 1.48 19.02 192.07 0.84 0.66 175.68 0.81 0.58 153.10 0.74 0.46 134.71 0.70 0.39 117.32 0.67 0.32 94.89 0.60 0.23 75.59 0.56 0.17
Cat_5 1.14 16.26 206.45 0.84 0.55 188.95 0.81 0.48 164.71 0.74 0.38 145.21 0.70 0.32 126.72 0.67 0.27 102.52 0.60 0.19 81.50 0.56 0.14
Cat_6 0.63 17.84 198.24 0.84 0.29 181.38 0.81 0.25 158.08 0.74 0.20 139.22 0.70 0.17 121.35 0.67 0.14 98.17 0.60 0.10 78.13 0.56 0.08
Cat_7 1.62 29.40 156.68 0.84 0.59 141.68 0.81 0.51 122.44 0.74 0.41 107.32 0.70 0.34 93.81 0.67 0.28 75.43 0.60 0.20 60.13 0.56 0.15
Cat_8 3.43, 23.17 175.58 0.84 1.41 160.21 0.81 1.23 138.84 0.74 0.97 122.11 0.70 0.82 106.38 0.67 0.67 85.92 0.60 0.49 68.42 0.56 0.37
Cat_9 1.56 27.85 161.01 0.84 0.58 146.01 0.81 0.51 126.15 0.74 0.40 110.72 0.70 0.34 96.69 0.67 0.28 77.85 0.60 0.20 62.02 0.56 0.15
Cat_10 3.43 20.14 186.49 0.84 1.49 170.52 0.81 1.31 148.55 0.74 1.04 130.60 0.70 0.87 113.66 0.67 0.72 91.92 0.60 0.52 73.27 0.56 0.39
Cat_11 1.86 18.91 192.66 0.84 0.84 176.22 0.81 0.73 153.57 0.74 0.58 135.14 0.70 0.49 117.70 0.67 0.44 95.20 0.60 0.29 75.83 0.56 0.22
Cat_12 1.69 16.89 203.17 0.84 0.80 185.93 0.81 0.70 162.06 0.74 0.56 142.82 0.70 0.47 124.57 0.67 0.39 100.78 0.60 0.28 80.15 0.56 0.21
Cat_13 0.76 30.86 153.33 0.84 0.27 138.50 0.81 0.23 119.66 0.74 0.18 104.81 0.70 0.15 91.62 0.67 0.13 73.61 0.60 0.09 58.69 0.56 0.07
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