Question

15.Development of IDF curve. A 20-year annual maximum series of 15 min, 30 min, min and 120 min storm depths are given in the table below. Determine the average intensities associated with return periods of 5, 10, 25, 50 and 100 years. Assume that extreme value type 1 Gumbel distribution fits the given rainfall series. Plot the curves! Use Excel. (Precipitation (depth) in INCHES) Precipitation (depth) Precipitation (depth) Precipitation (depth) Precipitation (depth) 60 minutes 120 minutes 15 minutes 30 minutes 3.150 1.600 4.100 1.900 3.860 2.200 1.450 1.570 1.370 1.650 1.810 1.440 1.430 1.280 1.360 1440 1.550 1.430 1.520 1.760 1.430 3 210 2.060 1.360 1100 1.165 1.000 1.260 1.310 1.080 1.080 0.970 1.011 106 1.160 1.020 1 130 1.250 1.300 1.100 1.410 1.410 1.220 1.780 1.930 1.561 2.040 2.150 1.620 1671 1.440 1.550 1.020 1.070 1.210 1.270 1.160 1.920 1.571 1.920 1.880 1.731 1.240 1170 1.100 1070 1.701 1.140 3.400

Answer 1

File Home Page Layout Formulas nsert Data Review View Foxit Store ivotTable Recommended Table Pictures Online Pictures Illustrations Recommended Charts My Add-ins PivotTables Tables Add-in G81 K-(6A.5)/3.14*(.5772+In[In(T/T-1)]) (Precipitation (depth) in inches) 6 Precipitation(depth) Precipitation(depth) Precipitation(depth) Precipitation(depth) 7 15 Minutes 30 Minutes 60 Minutes 120 minutes 2.06 3.15 3.86 2.2 1.45 1.57 1.37 1.65 1.81 1.44 1.28 1.36 1.44 1.55 1.43 1.52 1.76 1.43 3.21 1.83 1.36 1.25 1.78 1.93 1.561 2.04 2.15 1.62 1.44 1.55 1.62 1.92 1.571 1.92 1.88 1.731 3.4 1.91 1.165 12 1.26 1.31 1.08 0.97 1.011 1.06 1.16 1.02 1.13 1.41 1.41 1.22 1.02 1.07 1.21 1.27 1.16 1.27 1.24 1.17 2.63 1.33 4 15 19 1.07 1.701 1.14 24

36 37 38 39 Now, Rainfall intensity for different durations in inches/hr 40 15 Minutes Xt-Xavg +KtS 30 Minutes 1 hour 2 Hour 8.24 5.44 4.4 4.66 4 5.04 5.24 4.32 3.88 4.044 4.24 4.64 4.08 4.52 4.4 4.28 6.804 4.56 6.3 3.2 2.5 2.6 2.2 2.82 2.82 2.44 2.04 2.14 2.42 2.54 2.32 2.54 2.48 2.34 5.26 2.66 3.86 2.2 1.45 1.57 1.37 1.65 1.81 1.44 1.28 1.36 1.44 1.55 1.43 1.52 1.76 1.43 3.21 1.83 2.05 0.95 0.89 0.965 0.7805 1.02 1.075 0.81 0.72 0.775 0.81 0.96 0.7855 0.96 0.94 0.8655 1.7 0.955 43 45 46 47 48 49 50 51 52 53 54 56 57 58

59 60 61 The mean and standard deviation for the data for different durations is given as 62 Duration 15 Minutes 63 Mean 64 Std. Dev. 1.064424 65 66 Kt values are calculated for different return periods using Gumbel's Distribution 67 Kt.7796.577+n(In(T/T-1)) 68 T(years 69 Kt 70 71 The Rainfall intensities are calculated using 72 Xt Xavg+Kts 73 74 The intensities (inches/hr) for durations are tabulated below 75 76 Duration(hours 77 15 Minutes 78 30 Minutes 79 1 Hour 80 2 Hours 81 82 1 hour 30 Minutes 2.867778 1.076417 2 Hours 1.786667 0.662981 1.000639 0.328014 4.821556 25 0.719 1.3044 2.0436 100 2.59 3.1363 10 50 Return Period T (Years) 100 5.586877 6.209991 6.996813 7.578415 8.15991 3.641721 4.271856 5.067543 5.655697 6.243743 2.26335 2.65146 3.141536 3.503789 3.865975 1.236481 1.4285 1.670968 1.850194 2.029388 10 25 50