2. In the design of a borehole, the radius of influence R cannot be established precisely and, therefore, is commonly assumed to be 200 m. For a well of radius, rw 250 mm and transitivity T= 0.0208 s1 that is to supply 15 m/hr, determine: i. Drawdown below which the pump must be placed ii. The percentage error in drawdown if the correct radius of influence was 300 m. 2.72TZW Assume the borehole yield Q) %3D log. R /r

2. In the design of a borehole, the radius of influence R cannot be established precisely and, therefore, is commonly assumed to be 200 m. For a well of radius, rw 250 mm and transitivity T= 0.0208 s1 that is to supply 15 m/hr, determine: i. Drawdown below which the pump must be placed ii. The percentage error in drawdown if the correct radius of influence was 300 m. 2.72TZW Assume the borehole yield Q) %3D log. R /r

Fundamentals of Geotechnical Engineering (MindTap Course List)

5th Edition

ISBN:9781305635180

Author:Braja M. Das, Nagaratnam Sivakugan

Publisher:Braja M. Das, Nagaratnam Sivakugan

Chapter7: Seepage

Section: Chapter Questions

Problem 7.7CTP

See similar textbooks

Similar questions

A 0.34 m diameter well fully penetrates an unconfined aquifer which is 33.2 m thick. The drawdown at the pumping well is 1.34 m and the permeability of the gravel aquifer is 4.32 * 10-3 m/s. If the flow is steady-state and the discharge is 422.3 lt/min, a- find the drawdown at the site 132.4 m from the center of the pumping well, b- determine the radius of influence ‘r∞’ of this well under that discharge.
The time – drawdown data for a confined aquifer is given below for a discharge of 1500 gpm. The distance of the observation well is 300 ft. here, T=52849.388 ft^2/day and S=0.000568 A.Show that the basic criteria for using Cooper-Jacob approximation is satisfied. B.For the computed T and S values, what is the limiting value of time ‘t’ that satisfies the basic criteria of well function parameter ‘u’?
A 1m diametee well penetrates vertically through a confined aquifer 30m thick. When the well is pumped at 113 m^3/hr , the drawdown in a well 15m away is 1.8m, in another well 50m away, it is 0.50m. What is the approximate drawdown in the pumped well?
A 2 ft diameter well penetrates vertically through a confined aquifer 50 ft thick. Whenthe well is pumped at 500 gpm in 1 day, the drawdown in a well 50 ft away is 10 ft andin another well 100 ft away is 3 ft. The storativity of aquifer is 0.0005. What is the valuefor transmissivity and drawdown? Note; the piezometric head is 100ft from datum.Combination of thiem & thies equation
1) A triangular section has a side slope of s = 2, Manning's n = 0.02, Bottom slope of S0 = 0.005, depth, y = 2 m. Using Manning's equation (Eq. 24 in formula sheet) determine the flowrate Q. Use the Table in the last page to calculate A, and Rh (Hydraulic Radius) 2) Do the same for a rectangular section with B0 = 4 m, n = 0.015, S0 = 0.0025, and depth, y = 2 m.
derive a general expression for the wetted perimeter of a trapezoidal channel in terms of cross-sectional A, depth y and angle of slideslope. prove that Rh=y/2 for the section to have the best hydraulic efficiency
Course: Hydrology A 45 cm well in an unconfined aquifer of saturated thickness of 45 m yields 600 lpm under a drawdown of 3.0 m at the pumping well, (a) What will be the discharge under a drawdown of 6.0 m? (b) What will be the discharge in a 30 cm well under a drawdown of 3.0 m? Assume the radius of influence to remain constant at 500 m in both cases
A 2‐ft diameter well penetrates vertically through a confined aquifer 50 ft thick. When the well is pumped at 500 gpm, the drawdown in a well 50 ft away is 10 ft and in another well 100 ft away is 3 ft.(a) What is the approximate head in the pumped well for steady‐state conditions, and what is the approximate drawdown in the well?(b) Compute the transmissivity. Take the initial piezometric level as 100 ft above the datum.
Q#1(a) Water flows over a rectangular weir 3m long. The height of water surface over the weir is 1m. Calculate discharge over the weir by: Simple formula Francis’ formula Take Cd=0.62 and velocity of approach=2m/sec. Find the difference between the two discharges. (b) What is meant by “Hydraulic coefficient”? Explain different types of hydraulic coefficients. (c) What is a “Cippoletti weir” ?Prove that the side slope of a Cippoletti weir is 1:4.
A 1.15 m diameter pumping well penetrates vertically through a confined aquifer which is 42 m thick. While pumping at a rate of 2880 m3/day, the drawdown in an observation well 20 m away is 2.0 m. In another observation well, that is located 60m away, the drawdown is 0.45m. Initial piezometric level is 52m above the datum. Determine: The approximate head in the pumping well for steady state condition?The approximate drawdown in the pumping well ? The transmissivity of the aquifer ? The radius of influence of the pumping well?
A well with a diameter of 18 in. penetrates an unconfined aquifer that is 100ft thick. Two observation well are located at 100 ft and 235 ft from the well, and the measured drawdownsare 22.2ft and 21ft, respectively. Flow is steady and the hydraulic conductivity is 1400 gpd/ft^2. What is the steady-state rate of discharge from the well?
A trapezoidal channel with 3.0 bottom width and 1:1 side slope carries a discharge of 10?3 ? at a slope of 12cm/km. A hydraulic jump is formed in the channel with an initial depth of 0.6 m. Calculate the momentum function, the critical depth, and the conjugate depth.