Example 7. A catchment of 200 hectares area has rainfalls of 7.5 cm, 2.0 cm and 5.0 cm in three consecutive days. The average O index can be assumed to be 2.5 cm/day. Distribution- graph percentages of the surface runoff which extended over 6 days for every rainfall of 1-day duration are 5, 15, 40, 25, 10 and 5. Determine the ordinates of the discharge hydrograph by neglecting the base flow.

Example 7. A catchment of 200 hectares area has rainfalls of 7.5 cm, 2.0 cm and 5.0 cm in three consecutive days. The average O index can be assumed to be 2.5 cm/day. Distribution- graph percentages of the surface runoff which extended over 6 days for every rainfall of 1-day duration are 5, 15, 40, 25, 10 and 5. Determine the ordinates of the discharge hydrograph by neglecting the base flow.

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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Recorded flow data from a 7 sq. km. catchment due to a 1 hour rainfall event is given in Table 2. The base flow is 0.14 m³/s. Assume that the uniform rainfall over the catchment area was 39 mm. If the o-index of the catchment area is 21 mm/hr, calculate the ordinates of 1 hour unit hydrograph in Table 2. Table 2: Data for Question 2(b) (Draw the Table on a Page and Solve the Problem) Time Flow (hr) (m³/s) 0.5 1 3.0 2 7.5 3 6.0 4 4.5 5 3.0 2.1 7 1.5 8 1.1 9 0.8 10 0.5 11 0.2
Please solve it again because previous solutions were wrong.
Compute the diameter (cm) of the outfall required to drain storm water from the watershed described in figure below. Use rainfall intensity = 4 cm/hr. Average velocity of flow is 1 m/s. Other data are for: Area 1: C=0.5, area=0.005 km2. Area 2: C=0.4, area =0.01 km2. Area 3: C=0.7, area=0.015 km2.
Net Storm Rainfall Example 2-1 Rain falls as shown in the rainfall hyetograph (intensity Vs. time) in Fig. E2-1 (a). The o index for the Storm is 0.5 in./hr and is constant over 5 hr. Plot the net rainfall on the hydrograph (flow vs. time) given in Fig. E2-1 (a). Determine the total volume of runoff and the watershed area. 1cfs = 1.008 ac-in/hr 2.0 1.5 1.0 0.5 1 3. 4 Time (hr) 700 600 500 400 300 200 100 4 8 12 16 20 24 Time (hr) Time (hr) Q (cfs) Volume (cfs-hr) 0-2 2-4 4-6 6-8 8-10 10-12 12-14 14-16 16-18 18-20 20-22 22-24 24-26 16 Q (cfs) iT (in./hr)
Question- A peak flow of a flood hydrograph due to a 6 hour storm is 470 m³/s. The corresponding average depth of rainfall is 8 cm. Assume an Infiltration loss of 0.25 cm/hour and a constant base flow of 15 m³/s. What is the peak discharge of 6 hour unit hydrograph for this Catchment?
Please answer question 2
A drainage basin has a area of 7322 km2. The average annual precipitation for this area is 909 mm. The average surface water flow at the outlet of the catchment is 21.4 x 108 m3/year and the average groundwater flow out of the basin is 94.6 mm/year. Assume trailing zeros are significant if present. Determine the annual average evaporation in mm/year. (give your answer to one decimal place)
Question A 4-hour rainfall in a catchment of 250 km² produces rainfall depths of 6.2 cm and 5 ❤ cm in successive 2-hour unit periods. Assuming the index of the soil to be 1.2 cm/hour, the runoff volume is A 1.6 ha-m B D 16 ha-m 160 ha-m 1600 ha-m
Q.2 A catchment having an area of 150 km2 has the ø index 0.3 cm/hr. The base flow at the 3 outlet is 10m³/s. One hour unit hydrograph of the catchment area is triangular in shape with a time base of 20 hours. The peak ordinate occurs at 8 hours. If a rainfall of 4.5 cm occurs in 1 hour, then the peak ordinate of the flood hydrograph will be:
A reservoir had a water surface elevation of 110 m above the datum at the beginning of the month. In the same month, the reservoir received an average inflow of 7.5 cms (m3/s) from surface runoff sources. For the same period, the outflow from the reservoir had an average value of 5 cms. Further, in the same month, the reservoir received a rainfall of 180 mm and losses due to evaporation of 5 cm. Assume the area of the lake is 50 km2 acres and assume no contribution from groundwater storage. What is the water surface elevation of the reservoir after the month?
A 40-year annual series of eak river discharges with the mean equal to 15,000 cfs and standard deviation equal to 7,500 cfs approximates a normal distribution. (1) Determine the discharge woth a return period of 10 years. (2) Determine the discharge with a return period of 20 years. (3) what is the return period rhay corresponds to a discharge of period of 20 years. (3) What is the return period that corresponds to discharge of 20,000 cfs? (4) What is the probability that a discharge equal to or greater than 20,000 cfs will occur during a 5-year period?