Groundwater Flow to Wells. I. Overview A. Water well uses 1. Extraction 2. Injection.
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Transcript of Groundwater Flow to Wells. I. Overview A. Water well uses 1. Extraction 2. Injection.
![Page 1: Groundwater Flow to Wells. I. Overview A. Water well uses 1. Extraction 2. Injection.](https://reader030.fdocuments.us/reader030/viewer/2022013115/56649f565503460f94c79c05/html5/thumbnails/1.jpg)
Groundwater Flow to Wells
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I. Overview
A. Water well uses
1. Extraction
2. Injection
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I. Overview
A. Water well uses
B. Terms
1. Cone of depression
2. Drawdown
3. Unsteady Flow
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I. Overview
A. Water well uses
B. Terms
C. Goals
1. Compute dh/dt given knowledge
of the properties of the aquifer
2. Determine the properties of the aquifer based on the rate of dh/dt.
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I. Overview
A. Water well uses
B. Terms
C. Goals
D. General Assumptions
![Page 6: Groundwater Flow to Wells. I. Overview A. Water well uses 1. Extraction 2. Injection.](https://reader030.fdocuments.us/reader030/viewer/2022013115/56649f565503460f94c79c05/html5/thumbnails/6.jpg)
General Assumptions
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General Assumptions (continued)
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I. Overview
A. Water well uses
B. Terms
C. Goals
D. General Assumptions
E. Radial Flow
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II. Theis Method
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II. Theis Method
A. Additional AssumptionsThe aquifer is confined on the top and bottom
There is no source of recharge to the aquifer
The aquifer is compressible, and water is released instantaneously
from the aquifer as the hydraulic head is lowered.
The well is pumped at a constant rate.
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II. Theis Method
A. Additional Assumptions
B. The Equations
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II. Theis Method
A. Additional Assumptions
B. The Equations
ho -ht = Q* * wu
4πT
u = r2*S
4Tt
s = ho -ht
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THEIS CURVE
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II. Theis Method
C. Examples (with known values)
A well is located in an aquifer with a hydraulic conductivity of 15 m/d, storativityis 0.005, aquifer thickness is 20 m, and the pumping of the water well is occurringat a rate of 2725 m3/d. What is the drawdown at a distance of 7 m from the wellafter 1 day of pumping?
ho -ht = Q* * wu
4πT
u = r2*S
4Tt
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II. Theis Method
A. Additional Assumptions
B. The Equations
C. Examples (with known values)
D. Examples (with unknown values)
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THEIS CURVE
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DRAWDOWN DATA
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Problem: A well in a confined aquifer was pumped at a rate of 42,400 ft3/dfor 500 minutes. The aquifer is 48 ft. thick. Time drawdown data from an observation well located 824 ft away yields the following data (see previousslide of drawdown data).
Find T, K, and S.
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III. Jacob Straight Line Method
A. Overview
B. Conditions
C. The Equation
D. Example
T = 2.3Q
4πΔh
S = 2.25T*t0
r2
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III. Jacob Straight Line Method
D. Example
T = 2.3Q
4πΔh
S = 2.25T*t0
r2
Problem: A well in a confined aquifer was pumped at a rate of 42,400 ft3/dfor 500 minutes. The aquifer is 48 ft. thick. Time drawdown data from an observation well located 824 ft away yields the following data (see previousslide of drawdown data).
Find T, K, and S.
![Page 26: Groundwater Flow to Wells. I. Overview A. Water well uses 1. Extraction 2. Injection.](https://reader030.fdocuments.us/reader030/viewer/2022013115/56649f565503460f94c79c05/html5/thumbnails/26.jpg)
IV. Distance Drawdown MethodA. OverviewB. EquationsC. Example
T = 2.3Q
2πΔh
S = 2.25T*t
r02
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Distance Drawdown Method
0
2
4
6
8
10
12
14
16
1 10 100 1000
Distance (ft)
Dra
wd
ow
n (
ft)
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IV. Distance Drawdown MethodC. Example
T = 2.3Q
2πΔh
S = 2.25T*t
r02
A well is pumping 77,000 ft3/d, and has observational wells located 10, 40, 150,300, and 400 ft away from the pumping well. After 0.14 days of pumping, the Following drawdowns were observed in the observation wells (see graph).Determine T (ft2/d) and S of the aquifer.
Distance Drawdown Method
0
2
4
6
8
10
12
14
16
1 10 100 1000
Distance (ft)
Dra
wd
ow
n (
ft)
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V. Hzorslev Method(Slug or Bail Test)
K = r2*ln(L/R)
2Lt0.37
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Time since
injection h h/ho
0 0.88 1.000
1 0.6 0.682
2 0.38 0.432
3 0.21 0.239
4 0.12 0.136
5 0.06 0.068
6 0.04 0.045
7 0.02 0.023
8 0.01 0.011
9 0 0.000
Hzorslev Method
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0.01
0.1
1
0 1 2 3 4 5 6 7 8 9 10
Time (s)
h/h
oHzorslev Method
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V. Hzorslev Method(Slug or Bail Test)
K = r2*ln(L/R)
2Lt0.37
A slug test is performed by lowering a metal cylinder into a piezometer that isscreened in coarse sand. The inside of the bore hole has a radius of 0.500 ft, andthe inside radius of the piezometer is 0.083 ft. The screened section of the well is10 ft. The well recovery data is shown via tables and the respective graph. Determine the Hydraulic Conductivity of the aquifer.
0.01
0.1
1
0 1 2 3 4 5 6 7 8 9 10
Time (s)
h/h
o
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VI. Intersecting Pumping Cones and Well Interference
A. General Example
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A. Bounded Aquifers
1. Impermeable boundary
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A. Bounded Aquifers
1. Constant Head boundary
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VII. Recovery of Pumping Wells
A.Purpose
B.Example
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VII. Recovery of Pumping Wells
Time(min) Elevation (ft)
0 520
0.2 520.2
0.4 520.3
0.8 520.6
1 521
2 522
3 523
4 524
5 525
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VII. Recovery of Pumping Wells
Time(min) Elevation (ft)
0 520
0.2 520.2
0.4 520.3
0.8 520.6
1 521
2 522
3 523
4 524
5 525
1 ft3 = 7.48 gallons