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# Pumping In and Pumping Out Tests – 2

1 - Question

The formula for the pumping out test in an unconfined aquifer is given by _________

a) k=qπ1.36(H2−h2)log10Rr

b) k=q1.36(H2−h2)log10Rr

c) k=qπ(H2−h2)log10Rr

d) k=q1.36(H2−h2)

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Answer: bExplanation: From Darcy’s law, q=kAi A=2πxy i=dydx q=k2πxydydxordxx=k2πydy integrating between (R,r) for x and (H,h) for y, ∫Rrqdxx=2kπ∫Hhydy ∴ k=q1.36(H2−h2)log10Rr

2 - Question

The formula for the pumping out test in an unconfined aquifer is given by _________

a) k=qπ1.36(H2−h2)log10Rr

b) k=q1.36(H2−h2)log10Rr

c) k=q2.72b(H−h)log10Rr

d) k=q1.36(H2−h2)

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Answer: cExplanation: From Darcy’s law, q=kAi A=2πxb Where b=thickness of confined aquifer i=dydx q=k2πxb dxxordxx=k2πbdy integrating between (R,r) for x and (H,h) for y, ∫Rrqdxx=2kπb∫Hhdy ∴ k=q2.72b(H2−h2)log10Rr.

3 - Question

The permeability of the aquifer is ________ if the drawdown is 4m, discharge is 40litres/sec, thickness of confined aquifer is 30m and the radius of the well is 0.1m. The radius of influence is taken as 245m.

a) 36 m/day

b) 30 m/day

c) 26 m/day

d) 20 m/day

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Answer: aExplanation: Given, Drawdown=4m Discharge q=40litres/sec thickness of confined aquifer b=30m radius of the well r=0.1m radius of influence=245m the permeability is given by, k=q2.72b(H−h)log10Rr k=0.04(2.72∗30∗4)log102450.1 ∴k=36 m/day.

4 - Question

In the field determination, pumping must continue at a ________

a) uniform rate for sufficient time to approach steady state

b) non- uniform rate for sufficient time to approach steady state

c) uniform rate until just before time to approach steady state

d) non-uniform rate until just before time to approach steady state

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Answer: aExplanation: The steady state condition is the one in which the drawdown changes negligibly with time. In order to get accurate results, pumping must continue at a uniform rate for sufficient time in the field determination to approach steady state.

5 - Question

The U.S. Bureau of Reclamation (Earth manual 1960) has devised two types of pumping-in tests _________

a) open-end test and packer test

b) permeability test and radio test

c) dupin test and influence test

d) falling head and constant head permeability test

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Answer: aExplanation: The pumping-in tests includes open-end test and packer test. The falling head and constant head permeability test are also used to determine the permeability but are laboratory tests.

6 - Question

The formula for the open-end test is given by _________

a) k=q5.5rh

b) k=5.5rhq

c) k=q5rh

d) k=q0.5rh

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Answer: aExplanation: The permeability can be calculated from, k=q5.5rh where k=permeability q=discharge or constant rate of flow r=radius of casing h=differential head of water.

7 - Question

The coefficient of permeability by Packer for length greater than ten times the radius test is given by ________

a) k=q2πhlog10Lr

b) k=v2πLhlog10Lr

c) k=q2Lhlog10Lr

d) k=q2πLhlog10Lr

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Answer: aExplanation: The coefficient of permeability k for L ≥ 10r is given by, k=q2πLhlog10Lr where, q=discharge or constant rate of flow r=radius of casing h=differential head of water L=length of portion of hole tested.

8 - Question

The coefficient of permeability by Packer for length in the range 10r > L ≥r test is given by ________

a) k=q2πhlog10Lr

b) k=q2πLhlog10Lr

c) k=q2Lhlog10Lr

d) k=q2πLhsinh−1L2r

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Answer: dExplanation: The coefficient of permeability k for 10r > L ≥r is given by, k=q2πLhsinh−1L2r where, q=discharge or constant rate of flow r=radius of casing h=differential head of water L=length of portion of hole tested.