Question 52 A directly connected portion (to the outlet) of an Adelaide catchment (total Area A ha) was subjected to an industrial development Travel time before the development was t c minutes (to travel from the furthest point, P to the catchment outlet, O) After the development, travel time for the developed area is approximately t c1 minutes and that is for the undeveloped area still equals to t c The runoff coefficients at 10 year ARI, C 10 for the undeveloped (pervious) and developed (impervious) areas are C 1 and C 2 respectively Based on the data provided below, select the set of parameters for the analyses from the data The IFD data (mm hr) and Frequency conversion factors are given in Tables 4 and 5 respectively (a) Based on the data selected, indicate developed and undeveloped areas on a typical catchment Also indicate furthest point, P and the catchment outlet, O (b) Using Rational method of peak flow estimation, compute the percentage increase of the T year (ARI T years) design flood peak due to the development All the calculations need to be presented logically and clearly Total Area (A t ) t c (min) tc 1 (min) C 1 at 10 year ARI (previous) C 2 at 10 year ARI (impervious) ARI (T years) Developed area ( of A t ) 30Total Area (A t ) 4 30 15 0 25 0 8 70 40 Table 4 Frequency conversion factor Ft (for questions 52 ARI (T years) FI 1 0 8 2 0 85 5 0 95 10 1 20 1 05 40 1 13 60 1 17 80 1 19 100 1 2 Table 5 IDF data (mm hr) for Adelaide region (for questions 52 Duration (min) 5 10 15 20 25 1 42 9 32 18 26 5 22 83 20 22 2 57 95 43 34 35 62 30 65 27 11 24 43 22 32 20 61 19 19 ARI T (Years) 5 10 20 81 43 97 96 121 04 60 46 72 42 89 15 49 45 59 06 72 52 42 38 50 51 61 89 37 37 44 45 54 39 33 59 39 9 48 75 30 62 36 33 44 33 28 22 33 33 40 76 26 23 31 04 37 81 50 156 02 114 39 92 77 78 89 69 27 100 186 54 136 34 110 32 93 78 82 13 73 42 66 6 61 11 56 57 30 35 40 45 18 24 16 69 15 42 14 37 61 99 56 29 51 69 47 89 Table 4 Frequency conversion factor Ft (for questions 52 ARI (T years) FI 1 0 8 2 0 85 5 0 95 10 1 20 1 05 40 1 13 60 1 17 80 1 19 100 1 2 Table 5 IDF data (mm hr) for Adelaide region (for questions 52 Duration (min) 5 10 15 20 25 1 42 9 32 18 26 5 22 83 20 22 2 57 95 43 34 35 62 30 65 27 11 24 43 22 32 20 61 19 19 ARI T (Years) 5 10 20 81 43 97 96 121 04 60 46 72 42 89 15 49 45 59 06 72 52 42 38 50 51 61 89 37 37 44 45 54 39 33 59 39 9 48 75 30 62 36 33 44 33 28 22 33 33 40 76 26 23 31 04 37 81 50 156 02 114 39 92 77 78 89 69 27 100 186 54 136 34 110 32 93 78 82 13 73 42 66 6 61 11 56 57 30 35 40 45 18 24 16 69 15 42 14 37 61 99 56 29 51 69 47 89

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Question 52 A directly connected portion (to the outlet) of an Adelaide catchment (total Area = A ha) was subjected to an industrial development. Travel

Question 52

A directly connected portion (to the outlet) of an Adelaide catchment (total Area = A ha) was subjected to an industrial development. Travel time before the development was t_c minutes (to travel from the furthest point, P to the catchment outlet, O). After the development, travel time for the developed area is approximately t_c1 minutes and that is for the undeveloped area still equals to t_c. The runoff coefficients at 10-year ARI, C₁₀ for the undeveloped (pervious) and developed (impervious) areas are C₁ and C₂ respectively. Based on the data provided below, select the set of parameters for the analyses from the data. The IFD data (mm/hr) and Frequency conversion factors are given in Tables 4 and 5 respectively. (a) Based on the data selected, indicate developed and undeveloped areas on a typical catchment. Also indicate furthest point, P and the catchment outlet, O.

(b) Using Rational method of peak flow estimation, compute the percentage increase of the T-year (ARI = T years) design flood peak due to the development. All the calculations need to be presented logically and clearly.

Total Area (A_t)	t_c(min)	tc₁(min)	C₁at 10-year ARI (previous)	C₂at 10-year ARI (impervious)	ARI (T years)	Developed area (% of A_t) = 30Total Area (A_t)
4	30	15	0.25	0.8	70	40

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Table 4 Frequency conversion factor Ft (for questions 52 ARI (T-years) FI 1 0.8 2 0.85 5 0.95 10 1 20 1.05 40 1.13 60 1.17 80 1.19 100 1.2 Table 5 IDF data (mm/hr) for Adelaide region (for questions 52 Duration (min) 5 10 15 20 25 1 42.9 32.18 26.5 22.83 20.22 2 57.95 43.34 35.62 30.65 27.11 24.43 22.32 20.61 19.19 ARI = T (Years) 5 10 20 81.43 97.96 121.04 60.46 72.42 89.15 49.45 59.06 72.52 42.38 50.51 61.89 37.37 44.45 54.39 33.59 39.9 48.75 30.62 36.33 44.33 28.22 33.33 40.76 26.23 31.04 37.81 50 156.02 114.39 92.77 78.89 69.27 100 186.54 136.34 110.32 93.78 82.13 73.42 66.6 61.11 56.57 30 35 40 45 18.24 16.69 15.42 14.37 61.99 56.29 51.69 47.89 Table 4 Frequency conversion factor Ft (for questions 52 ARI (T-years) FI 1 0.8 2 0.85 5 0.95 10 1 20 1.05 40 1.13 60 1.17 80 1.19 100 1.2 Table 5 IDF data (mm/hr) for Adelaide region (for questions 52 Duration (min) 5 10 15 20 25 1 42.9 32.18 26.5 22.83 20.22 2 57.95 43.34 35.62 30.65 27.11 24.43 22.32 20.61 19.19 ARI = T (Years) 5 10 20 81.43 97.96 121.04 60.46 72.42 89.15 49.45 59.06 72.52 42.38 50.51 61.89 37.37 44.45 54.39 33.59 39.9 48.75 30.62 36.33 44.33 28.22 33.33 40.76 26.23 31.04 37.81 50 156.02 114.39 92.77 78.89 69.27 100 186.54 136.34 110.32 93.78 82.13 73.42 66.6 61.11 56.57 30 35 40 45 18.24 16.69 15.42 14.37 61.99 56.29 51.69 47.89