10-min unit hydrograph for a catchment is given in Table 1 below. Table 1: 10-min Unit Hydrograph Time (min) 05 Flow (m³/s) 0 0.5 1.0 1.4 1.75 1.95 2.0 1.8 1.25 0.6 10 15 20 25 30 35 40 45 50 Time (min) 0-20 20-40 a. What is the area of the catchment? b. Construct a storm hydrograph resulting from the 40-min rainfall event. The rainfall excess depths are provided in Table 2. Determine the peak discharge resulting from this 40-min rainfall event. 0 Table 2: Rainfall Excess Depths Rainfall Excess (mm)

10-min unit hydrograph for a catchment is given in Table 1 below. Table 1: 10-min Unit Hydrograph Time (min) 05 Flow (m³/s) 0 0.5 1.0 1.4 1.75 1.95 2.0 1.8 1.25 0.6 10 15 20 25 30 35 40 45 50 Time (min) 0-20 20-40 a. What is the area of the catchment? b. Construct a storm hydrograph resulting from the 40-min rainfall event. The rainfall excess depths are provided in Table 2. Determine the peak discharge resulting from this 40-min rainfall event. 0 Table 2: Rainfall Excess Depths Rainfall Excess (mm)

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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A watershed of (30+X) km2 was subjected to a storm of 2-h duration from which the following information are recorded in Table a) Obtain a Unit Hydrograph for this watershed knowing that the base flow in the stream is estimated at 2 m3/s. b) Derive and plot 6-h Unit Hydrograph for the catchment area. Time (hours) 0 12345678 Discharge (m3/s) 2 15 30 37 30 22 16 12 2
Problem 3 The table below contains the data for a one-hour unit hydrograph. Time Q (hr) (cfs/in) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 145 246 359 979 432 246 134 65 32 0 (a) Determine the area of the watershed to which this unit hydrograph corresponds. Report your answer in acres. (b) Assume a very intense 3-hour storm occurs shortly after a rainy period, so the ground is very saturated. The runoff from the first one-hour interval of the storm totals 0.5 in., the runoff from the second one-hour interval is 2.5 in, and the runoff from the third one-hour interval totals 1.7 in. The baseflow during and after the storm is 80 cfs. Derive the storm hydrograph for this 3-hour storm. table that clearly indicates how you used the unit hydrograph, sample calculations Provide a with sufficient explanation, explanatory sketches, and a graph of the storm hydrograph. (c) Determine the peak discharge that will occur in the river if this 3-hour storm occurs.
How would you go about deriving a UH from a catchment for which data (catchment area, rainfall and discharge values) are available? Derive a hyetograph from the incident rainfall (losses do not need to be considered to derive a UH); Determine the UH using the formula "Ui = Qi/P" (for a single interval hyetograph) or using "deconvolution" (for a multiple interval hyetograph). Estimate direct runoff hydrograph by subtracting baseflow from observed stream flow data; Estimate the total runoff volume and the direct runoff depth over the catchment; Determine the UH ordinates using the formula "Unit hydrograph = Direct runoff hydrograph x 1/Direct runoff depth"; Estimate catchment losses and subtract these from the incident precipitation to obtain excess rainfall; the duration of the excess rainfall is used as the duration of the UH. Determine the precipitation volume for each time interval; Use UH superposition and proportionality principles to derive a direct unit hydrograph; Estimate…
Derive and plot 3-hour Unit hydrograph for a stream which drains an area of around (401) km2. Time-discharge data of the storm is given is in Table. Assume the base flow as 2 m3 /sec. Time (Hrs.) 0 3 Flow (m³/s) 2 6 6 9 11 13 12 15 18 21 10 8 6 4 24 2
Separate the baseflow from the stream flow hydrograph using the straight-line method. What is the baseflow? Calculate the direct runoff hydrograph (DRH) and plot it as an x-y scatter plot. Time (hr) Discharge (cfs) 0.0 60 0.5 54 1.0 50 1.5 90 2.0 137 2.5 176 3.0 200 3.5 198 4.0 140 4.5 97 5.0 60 5.5 40 6.0 35 6.5 32 7.0 29 7.5 24 8.0 22 8.5 20 9.0 20 9.5 19 10.0 19 10.5 18 11.0 18 11.5 18 12.0 17
Problem 3. Given below are the daily mean flows in cubic meter per second at a gaging station for a period of 5 days. What is the mean flow rate for the period of cubic meters per second? What is the total discharge during the period in cubic meters? If the drainage area is 1958 km', what is the runoff volume in millimeters? Day 1 | 2 | 3 4 | 5 Flow, m'/s 19.8 135.9 87.8 57.2 37.1 Problem 4. Using the data of prob. 4-3, and relationship of Fig. 4-16, estimates the peak flow
Derive a 2-hr unit hydrograph using the Snyder method for a watershed of 70 km2 area, with a main stream that is 9 km long. Also, the distance measured from the watershed outlet to a point on the stream nearest to the centroid of the watershed is 5 km. Take Ct = 3.0 and Cp = 0.70. Graph the 2-hr unit hydrograph for the watershed.
Example 4. Following are the ordinates of a storm hydrograph of a river draining a catchment area of 423 km² due to a 6-h isolated storm. Derive the ordinates o f a 6-h unit hydrograph for the catchment Time from start of storm (h) -6 0 6 12 18 24 30 36 42 48 Discharge (m³/s) 10 10 30 87.5 115.5 102.5 85.0 71.0 59.0 47.5 Time from start of storm (h) 54 60 66 72 78 84 90 96 102 Discharge (m³/s) 39.0 31.5 26.0 21.5 17.5 15.0 12.5 12.0 12.0
%VY . Q1: A catchment area is 5 square miles and the total direct Runoff (E D. R = 11150 ft / sec). Estimate the base flow for the data shown in the table below? Time 2 3 4 5. 6. 500 500 1200 2250 2920 2670 2060 1430 Total Flow(ft/sec) 202.57 | 506.43 700.32 627.97 451.44 269.13 11 U.H 10 1100 910 Time 9 12 13 14 15 16 Total 780 650 530 510 510 500 Flow(ft'/sec) U.H 173.6 118.65 81.03 52.09 28.94 11.57 2.89 Q2: Develop a 3-hr synthetic unit hydrograph for the catchment are using Snyder's method only. If the catchment area is 400 kan?, L= 25 kam and La km, assuming C15 and C,-0.7 •,.0 |||||||||||||1||||||| إلغاء إعادة تعي ين
Question 2 Route the inflow hydrograph through a reservoir as indicated in Table 2. The crest height of the spillway is 50 ft and storage capacity at this level is 116 ft3/s-day. The reservoir routing curves graph is given in Figure 1. Perform calculation until the outflow value is equal to zero. Based on the obtained result, plot the inflow and outflow hydrographs. Table 2 0.4 1.6 2 2.4 2.8 Time (day) 0 Flow (ft³/s) 0 0.8 120 1.2 229 56 380 268 155 50 Figure 1 25/atO (ft/s.day)-primary x-axis 700 800 900 1000 54.0 53.5 53.0 52.5 52.0 51.5 Elevation vs Storage (curve a) Elevation vs 25/De-O (curve b) Elevation vs Outflow (curve c) 51.0 50.5 50.08 49.5 110 230 0 Water Surface Elevation (tt) 400 W 500 130 100 600 150 200 190 170 210 Storage (ft³/s.day) - secondary x-axis 300 400 500 Outflow (ft³/s.day) - tertiary x-axis 600 250 1100 700