Determine the composite SCS runoff curve number for a 600-acre basin that is entirely in Soil Group B. The land use is 50% straight-row crops under poor conditions, and 50% meadow under good conditions. Use the following values in your solution, Table 4.11 → Straight - Row Crops in Poor Condition CN = 81 Table 4.11 → Meadow in Good Condition CN = 58

Determine the composite SCS runoff curve number for a 600-acre basin that is entirely in Soil Group B. The land use is 50% straight-row crops under poor conditions, and 50% meadow under good conditions. Use the following values in your solution, Table 4.11 → Straight - Row Crops in Poor Condition CN = 81 Table 4.11 → Meadow in Good Condition CN = 58

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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Problem 3.24 (page 119): The soil in a watershed has the following properties: 0, = 0.02, 0fe= 0.25, and 0 = 0.38. The watershed has a composite ARC II curve number of CN 80. A storm with a rainfall of 30 mm occurs in dormant season. During the five days before the storm begins, the total rainfall is 25 mm. Estimate the direct runoff from this storm using the MORE and SCS-CN models. %3D %3D %3D
Problem #2: A 700,000 m2 watershed is 30 percent Agricultural and 70 % urban. The agricultural land is 40 % cultivated with conservation treatment, 35 % meadow in good condition, and 25 % forest land with good cover. The urban area is residential: 60 % on 1350 m2 lots, 25 % on 1000 m2 lots, and 15 % streets and roads with curbs and storm sewers. The soil group is B. Determine a composite CN and the total discharge from a 150 mm for 24- hour storm duration.
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A 200-hectare watershed is slated for commercial and business development. Currently the watershed is open space (good condition) with 35% B-soils and 65% D- soils. a) Find the CN for the soil before and after development b) Find the weighted CN (include the equation and calculation, c) Determine the increase in runoff depth from a 10 cm rainfall event due to developing the watershed 3.
Estimate ∅-index for a watershed having an area 5 acres. The runoff volume caused by the rainfall is 56000 ft^3. Round off your answer to the nearest whole number. Indicate the unit. Plot the hyetograph and superimpose the final ∅-index. (1 acre = 43560 ft^2) * Using the rounded-off ∅-index, estimate the volume of infiltration losses in cubic feet. *
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A watershed is 30% meadow (good condition) and 70% commercial and business areas (85% impervious). The watershed has 50% soil group C and 50% soil group D. Calculate the weighted Curve Number for the whole watershed. (CN for different land uses and Hydrologic Soil Groups are provided in the table below (Table 2-1 of the textbook)). Land Use Description Cultivated land¹ Without conservation treatment With conservation treatment Pasture or range land Poor condition Good condition Meadow Good condition Wood or forest land Thin stand, poor cover, no mulch Good cover² Open spaces, lawns, parks, golf courses, cemeteries, etc. Good condition: grass cover on 75% or more of the area Eric Fair condition: grass cover on 50%-75% of the area Commercial and business areas (85% impervious) Industrial districts (72% impervious) Residential³ Average lot size 1/8 ac or less 1/4 ac 1/3 ac 1/2 ac 1 1 ac Paved parking lots, roofs, driveways, etc.5 Streets and roads Paved with curbs and storm sewers Gravel…
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A reservoir is located at the outlet of a 150 sq. mile watershed. Water budget data are: Mean annual rainfall over the region = 38 inches Mean annual watershed runoff = 13 inches Mean annual reservoir evaporation = 49 inches Mean daily withdrawal from reservoir = 100 MGD If the mean Feservoir surface area is 4000 acres, determine: (a) Volume of water evaporated from lake in acre-ft./yr. (b) Watershed runoff or inflow into the reservoir in acre-ft./yr. (c) Watershed runoff or inflow into reservoir in cfs (d) Volume of rainfall input to reservoir in acre-ft./yr. (e) Mean withdrawal/draft from the reservoir in acre-ft./yr. (f) Net loss/gain of reservoir storage in acre-ft./yr.
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5.3 Estimate the runoff volume, in mm of depth, from 80 mm of rainfall on a 90-ha watershed during the growing season. Assume antecedent rainfall condition II, 50 ha of row crop contoured with terraces, poor condition, soil group C, and 40 ha of alfalfa, straight, good condition, soil group B. 5.3 Estimate the runoff volume, in mm, m3, and ha·m, for the watershed and conditions in Problem 5.2, except that a 60-mm storm occurred 3 days before the 80-mm rainfall. 5.4 Estimate the runoff volume, in mm, for the watershed and conditions in Problem 5.2, except that no rainfall occurred for 6 days before the 80-mm rainfall. 5.5 Estimate the runoff volume, in mm, for a 24-h, 50-yr return period storm at your location. Assume the watershed conditions in Problem 5.2.