3. The cumulative rainfall recorded over a catchment area of 18.5 km for a 60-min storm...

 

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3. The cumulative rainfall recorded over a catchment area of 18.5 km² for a 60-min storm event and the discharge measured at the outlet of the catchment area is given in Table 1 below. Plot the rainfall (in inverted position) and hydrograph on the same graph using two scales on Y-axis. The stream is perennial, and the base flow at the outlet is 40 m³/s. Neglecting the loss due to evapotranspiration, determine the total amount of water in mm that infiltrated to the ground. (Answer: 4.38 mm) Cumulative Time (minutes) Rainfall (mm) 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 5.4 12.2 22.2 28.4 30.4 32 Table 1. Discharge at outlet of catchment (m³/s) 40.00 43.61 58.06 83.34 123.08 162.81 195.32 215.54 166.42 96.71 68.90 54.45 47.22 45.42 43.61 43.61 42.17 41.44 40.00 4. Based on data given in Question 3, plot rainfall excess (in inverted position) and direct runoff ordinates (DRO) on the same graph using two scales. Consider uniform seepage loss throughout the rainfall period. Verify that the amount of rainfall excess is equal to the total amount of DRO. 5. From the data given in Question 3, determine the peak flow, lag time, time of rise, time base and estimate time of concentration. 3. The cumulative rainfall recorded over a catchment area of 18.5 km² for a 60-min storm event and the discharge measured at the outlet of the catchment area is given in Table 1 below. Plot the rainfall (in inverted position) and hydrograph on the same graph using two scales on Y-axis. The stream is perennial, and the base flow at the outlet is 40 m³/s. Neglecting the loss due to evapotranspiration, determine the total amount of water in mm that infiltrated to the ground. (Answer: 4.38 mm) Cumulative Time (minutes) Rainfall (mm) 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 5.4 12.2 22.2 28.4 30.4 32 Table 1. Discharge at outlet of catchment (m³/s) 40.00 43.61 58.06 83.34 123.08 162.81 195.32 215.54 166.42 96.71 68.90 54.45 47.22 45.42 43.61 43.61 42.17 41.44 40.00 4. Based on data given in Question 3, plot rainfall excess (in inverted position) and direct runoff ordinates (DRO) on the same graph using two scales. Consider uniform seepage loss throughout the rainfall period. Verify that the amount of rainfall excess is equal to the total amount of DRO. 5. From the data given in Question 3, determine the peak flow, lag time, time of rise, time base and estimate time of concentration.

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