Which of following statements about unconfined aquifers is FALSE? recharge occurs only over a limited area of the aquifer the level of water in an observation well indicates the level of the water table springs occur where the water table intersects the surface if a well is pumped a cone of depression develops

Which of following statements about unconfined aquifers is FALSE? recharge occurs only over a limited area of the aquifer the level of water in an observation well indicates the level of the water table springs occur where the water table intersects the surface if a well is pumped a cone of depression develops

Principles of Geotechnical Engineering (MindTap Course List)

9th Edition

ISBN:9781305970939

Author:Braja M. Das, Khaled Sobhan

Publisher:Braja M. Das, Khaled Sobhan

Chapter7: Permeability

Section: Chapter Questions

Problem 7.22P: Refer to Figure 7.24. The following data were collected during the field permeability measurement of...

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1. In an unconfined aquifer, is the piezometric surface above or below the upper boundary of the aquifer? Explain. 2. What is the general shape of the piezometric surface surrounding a single pumping well?
Explain why the bottom of the aquifer is always used as the datum for head calculations when dealing with unconfined aquifers.
Name the two types of groundwater aquifers. Describe how they differ. What type of aquifer generally occurs closest to the land surface (i.e. is shallowest in the subsurface)? In an unconfined aquifer, what physical boundary does the piezometric surface correspond to?
In confined or unconfined aquifers water levels in wells are above the top of the aquifer?
A 30 cm well completely penetrates an unconfined aquifer of saturated depth 40 m. After a long period of pumping at a steady rate of 1500 lpm, the drawdown in two observation wells 25 and 75 m from the pumping well were found to be 3.5 m and 2.0 m respectively. a.) Determine the transmissivity (m^2/s) of the aquifer. b.) What is the drawdown (m) at the pumping well?
An artesian well is pumping water from a confined aquifer (thickness = 12 m) at a flow rate of 0.024 m3/s. The piezometric surface is 50 m above the bottom of the confining layer. In two monitoring wells (no pumping) located 15 m and 150 m away from the pumping well, steady-state drawdowns of 4 m and 1 m are observed, respectively. What is the intrinsic permeability of the aquifer (assuming the groundwater temperature is 15 ).
Differentiate confined and unconfined aquifer.
A confined aquifer is recharged by a continuous supply of water from the certain source. The ave. Thickness of the aquifer was determined to be 25m and the ave width is 4 km. The hydraulic conductivity ( coefficient permeability ) of the aquifer was obtained at 40m per day and its porosity is 25% .The piezometer heads in two wells 1.325km apart are 65 m and 60m . from a common reference datum.From the given data, obtain: 1) The rate of flow through the aquifer in cubic meter per day; 2) Evaluate the seepage velocity in meters per day; 3) Estimate the time of travel, in days, from the head of the aquifer to a point 4km downstream.
Discuss the importance of aquifers in aquatic ecosystem and sketch thecomparison between confined and unconfined aquifers.
b) A 30-cm well fully penetrates an unconfined aquifer of saturated depth 25 m. When a discharge of 2100 lpm was being pumped for a long time, observation wells at radial distances of 30 m and 90 m indicated drawdown of 5 and 4 m respectively. Estimate the coefficient of permeability and transmissibility of the aquifer. What is the drawdown at the pumping well?
A pump well is dug through a confined aquifer having a thickness of 32 meters. The piezometric surface of the aquifer is 18 meters measured from the top impermeable layer. The first observation well is 75 feet directly west of the pump well and the second observation well is 75 feet directly north of the first observation well. Determine the hydraulic conductivity of the aquifer if it supplies a discharge of 10 liters per second and the drawdown of the observation wells are 13 feet and 23 feet.
The discharge from a fully penetrating well operating under steady state in a confinedaquifer of 35 m thickness is 2000 lpm. Values of drawdown at two observation wells 12 and 120 m away from the well are 3.0 and 0.30 m respectively. Determine the permeability of the aquifer.