Lines delineating a particular measurement are drawn within the watershed. Precipitation data and the area in between each isohyet are shown in the table below. Estimate the average precipitation within this watershed. Isohyetal line (cm) Area (cm2) 30 - 40 40 - 50 50 - 60 60 - 70 70 - 80 80 - 90 90-100 32 162 155 92 228 120 65

Lines delineating a particular measurement are drawn within the watershed. Precipitation data and the area in between each isohyet are shown in the table below. Estimate the average precipitation within this watershed. Isohyetal line (cm) Area (cm2) 30 - 40 40 - 50 50 - 60 60 - 70 70 - 80 80 - 90 90-100 32 162 155 92 228 120 65

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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Question 4: The isohyets due to a storm in a watershed were calculated and the areas bounded by the isohyets were tabulated as below: Isohyets (inch) Area (mi^2) 10-8 30 8-6 140 4-6 80 2-4 180 0-2 20 Estimate the mean rainfall over the basin
A watershed with an area approximated by a circle of diameter 100 km. Five raingage stations are distributed over the watershed to record the precipitation data. The coordinates of the five stations and the center of the watershed and the annual precipitation records during the year 2020 are given in the table below: Centre: (100, 100) Diameter: 100 km. Distance are in km Station 1 3 4 Coordinates (30, 80) (70, 100) (100, 140) (130, 100) (100, 70) Precipitation (cm) 85.0 135.2 95.3 146.4 102.2 Your job is to compute the average annual precipitation using Thiessen polygon method.
A watershed has five rain gauge stations. In a year, the annual rainfall recorded by rain gauges are 115.5, 106.8, 125.4, 95.6 and 90.4 cm. For a 5% error in estimation of mean rainfall, the number of additional gauges required are (in integer).
A watershed covering 28.16 mi2 has a system of seven rainfall gages, as shown on the map in the Figure. Using the total storm rainfall depths given in the accompanying table, determine the average rainfall over the watershed using: (a) arithmetic averaging and (b) the Thiessen polygon method. Gage ABCDEFG А с P₁ (in.) 5.13 6.74 9.00 6.01 5.56 4.98 4.55 A₁ (mi²) 1.74 6.70 1.77 13.02 0.83 2.68 1.42 28.16 B. . E 1 in. = 3.9 mi .F . G
Example-1 A 4-hour storm occurs over an 80 km² watershed. The details of the catchment are as follows. Sub Area (km²) 15 25 35 5 Index (mm/hour) 10 15 21 16 1st hour 16 16 12 15 Hourly Rain (mm) 2nd hour 48 42 40 42 3rd hour 22 20 18 18 4th hour 10 Calculate the runoff from the catchment and the hourly distribution of the effective rainfall for the whole catchment.
The eight-hour unit hydrograph (UH) of a watershed having a drainage area equal to 334.08 km² is as follows: Time (h) UH (cms/cm) 0 0 8 16 24 32 40 48 2.40 17.45 45.30 24.90 12.30 8.75 56 4.90 For a storm over the watershed having excess rainfall of 12 cm for the first eight hours and 30 cm for the second eight hours, and assuming a constant baseflow of 150 cms, determine the following: a) the total direct runoff hydrograph (DRH, m³/s), b) the total volume of direct runoff hydrograph (m²), c) the depth of direct runoff hydrograph (cm),
A catchment area is presented in the Figure 1. Six rainfall gauges A, B, C, D, E and F are spread over this watershed and nearby. The inter isohyets areas I, II, II, IV and V are given as 20, 50, 70, 90, and 10 km? respectively. All the rainfall and isohyets are given in cm. Estimate the mean precipitation over this catchment area using arithmetic mean and isohyetal methods.
The six-hour unit hydrograph (UH) of a watershed having a drainage area equal to 393 km² is as given in the table below. 30 Time (hr.) UH Ordinates (m/s-em) 6 12 30.9 18 24 41.8 36 5.5 42 1.8 65.6 14.6 1.8 For a storm over the watershed having excess rainfall of 5.0 cm for the first six hours and 15.0 cm for the second six hours, compute for the direct and streamflow hydrograph, assuming a constant baseflow of 100 m/set. What is the depth of direct runoff? Depth of effective rainfall? Runoff depth from the UH in cm?
Question 3: Use both of Arithmetic Mean and Thiessen Polygon Methods to calculate the areal rainfall intensity for the watershed given below in (cm) (Inside the black box only) 4 6.0 1 Station No. Intensity (cm.) 2 4 3 5 1 5.0 2 3.0 3 4.0 5 7.0
Compute the runoff from a 5-in. rainfall from a watershed which has four soil groups overall and the land cover is fair grass cover. Also, estimate the effect of urbanization if the land cover changed into four urban categories as shown below: Land Use Land use Soil Group Before Urbanization After urbanization Grass Residential 40% C Grass Grass 25% D Grass Commercial 20% Grass Industrial 15% D CN CN Before Urbanization After Urbanization 79 83 83 80 79 94 33 83 93
Figure 2.2 shows a catchment with seven rain guage stations inside it and three stations outside. The rainfall recorded by each of these stations are indicated by the figure. Draw the figure to an enlarged scale and calculate the mean precipitation method by (a) Isohyetal method and by (b) Arithmetic-mean method.
A catchment has 4 sub areas. The annual precipitation and evaporation from each of the the sub-areas are given below. Assume that no change in the groundwater storage on an annual basis and calculate for the whole catchment the values of annual average precipitation and evaporation. What are the annual runoff coefficients for the sub-areas and for the total catchment taken as a whole? Sub Area Area (Mm^2). Annual Precipitation (mm) Annual Evaporation (mm). A 10.70 1030 530 В 3 830 438 8.20 900 430 D 17 1300 600 The annual average precipitation is mm The annual average evaporation is mm Runoff coefficient @ sub area A is Runoff coefficient @ sub area B is Runoff coefficient @ sub area C is Runoff coefficient @ sub area D is Total runoff coefficient is