This document contains questions from an exam on ground water development and management. The questions cover topics such as aquifer properties, well hydraulics, coastal aquifers, groundwater modeling, and artificial recharge. Multiple choice and numerical problems are presented relating to confined and unconfined aquifers, well testing, permeability, storage coefficients, drawdown, and sea water intrusion.

1. JNTUW
ORLD
Code No: 07A80102 R07 Set No. 2
IV B.Tech II Semester Examinations,April/May 2012
GROUND WATER DEVELOPMENT AND MANAGEMENT
Civil Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. Explain the following
(a) homogeneous isotropic
(b) homogeneous anisotropic
(c) heterogeneous isotropic
(d) heterogeneous anisotropic. [16]
2. Examine the formation of mounds beneath the square, hexagonal, circular, tri-
angular and rectangular recharge basins, having equal areas and equal recharge
rates. Discuss the influence of lateral variation of hydraulic conductivity under a
rectangular recharge basin. [16]
3. Rainfall and water-level fluctuation, as given below, are available for a station.
Compute
(a) minimum rainfall required to effect water level rise and
(b) average water level fluctuation for the period of rainfall record. [8+8]
Year 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984
Rainfall(m) 0.97 0.25 0.32 0.58 0.70 0.91 1.13 0.86 0.50 1.19
Water level rise(m) 2.7 3.0 1.45 0.75 3.5
4. Two rivers A and B run parallel to each other and fully penetrate the unconfined
aquifer situated on a horizontal impervious base. The rivers are 4.0 km apart and
the aquifer has a permeability of 1.5m/day. In an year, the average water surface
elevations of the rivers A and B, measured above the horizontal impermeable bed,
are 12.0 m and 9.0 m respectively. If the region between the rivers received an
annual net infiltration of 20 cm in the year, estimate:
(a) The location of the groundwater table divide and
(b) The average daily groundwater discharge into the rivers. A and B from the
aquifer between them. [16]
5. Two observation wells located at a distance of 395 m and 475 m respectively from the
production well measure a drawdown of 56 cm and 46 cms respectively after 5 hours
of pumping at the rate of 3000 m3
/day. The discharging well fully penetrates the
confined aquifer. Compute the parameters T and S and the radius of influence of
the well after 1 day. Assume Jacob’s drawdown method is applicable. [16]
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2. JNTUW
ORLD
Code No: 07A80102 R07 Set No. 2
6. (a) Discuss the geological formation in India which have potential as aquifers.
(b) In a laboratory test of an aquifer material a fully saturated sample of volume
5liters was taken and its initial weight of 105 N was recorded. When allowed
to drain completely it weight of 93 N was recorded at this stage. Calculate the
specific yield and relative density of the solids.(Assume unit weight of water
γ = 9.79 kN/m3
). [8+8]
7. The height of a point R on a fresh/salt water interface above the datum is 11m in a
coastal confined aquifer of thickness 39m and hydraulic conductivity kf = 2.1m/d.
A well (A) 12.23m away from the toe bottoming at R measures a piezometric head
of 52m above the datum, whereas the head is 51.87m in another well (B)located
22.23m from the toe. Assuming a uniform hydraulic gradient compute:
(a) The interface length L within the confined aquifer.
(b) The height of the interface above the datum at a distance L/2 from the coast.
(c) The head in well (A) above sea level when the interface at R moves up by 8m.
(d) Check the applicability of the Ghyben-Herzberg relation.
Given ρf = 1000kg/m3
, ρs = 1025kg/m3
. [16]
8. Compute the depth of occurrence and thickness of the aquifer from the flowing data
that were obtained from a seisimic refraction investigation in an alluvial area. Also,
find the depth to bed rock at the site of investigation. If a geophone is placed along
with the shot point what will be the first arrival time recorded there. In addition,
compute the cross over and critical distance for the seismic rays refracted from the
bed rock. [16]
x(m) 10 20 30 40 60 80 100 120 140 160 200
t(ms) 19.5 40 60 80 92 105 118 130 134 138.3 147
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3. JNTUW
ORLD
Code No: 07A80102 R07 Set No. 4
IV B.Tech II Semester Examinations,April/May 2012
GROUND WATER DEVELOPMENT AND MANAGEMENT
Civil Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. List out various methods for determination of permeability and explain any one in
detail along with a neat sketch. [16]
2. (a) A 20cm well completely penetrates an artesian aquifer. The length of the
strainer is 15m. What is its yield for a drawdown of 3m. Assume K=35m/day
and R=300m. If the diameter of the well is doubled find the percentage
increase in the yield, the other conditions remaining the same.
(b) If an artesian well produces 250 lpm with a drawdown of 3m in the pumping
well, what is the rate discharge with 4 m drawdown. Assume equilibrium
conditions and negligible well losses. [8+8]
3. (a) What is reverse seismic profiling? Draw a schematic diagram to explain the
determination of a sloping aquifer top.
(b) Derive expressions for cross over distance and critical distance for a three -
layer formation using the seismic refraction technique. [8+8]
4. In a sea water intrusion problem involving a confined aquifer of thickness 45 m
and fresh water hydraulic conductivity 7.5 m/d, the height of the salt/fresh water
interface above the datum is 8.2 m at a distance of 125 m from the toe of the
interface. If the thickness of the impervious overburden below sea level is 5 m,
compute:
(a) The fresh water hydraulic gradient at a distance of 252 m from the seacoast,
(b) The piezometric head above mean sea level at a distance of 100 m from the
seashore.
ρf = 1000kg/m3
, ρs = 1025kg/m3
. Assume a steady constant fresh water flow and
that the G-H theory is applicable. [16]
5. Consider an artificial recharge project in India and examine its environmental im-
pact assessment. What is your opinion about the technical feasibility and economic
viability of this project vis--vis its impact on the environment? [16]
6. (a) In a phreatic aquifer extending over 1 km2
the water table was initially at 25m
below ground level. Sometimes after irrigation with a depth of 20cm of water,
the water table rose to a depth of 24m below ground level. Later
3 × 105
m3
of water was pumped out and the water table dropped to 26.2 m
below ground level. Determine:
i. specific yield of the aquifer,
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4. JNTUW
ORLD
Code No: 07A80102 R07 Set No. 4
ii. deficit in soil moisture (below field capacity) before irrigation.
(b) In an area of 100 ha, the water dropped by 4.5m. If the porosity is 30% and
the specific retention is 10% determine:
i. the specific yield of the aquifer,
ii. change in ground water storage. [8+8]
7. A production well penetrating fully into a confined aquifer of thickness 9.15 m
discharges at a rate of 1200 m3
/d. An observation well is located at a discharge of
95 m from the production well and the following time drawdown data are observed.
Drawdown (m) 35 150 202 255 305
Time (mins)60 100 180 300 500 800
Compute the aquifer parameters T and S respectively using Jacob’s drawdown
method. [16]
8. Calculate groundwater recharge or discharge of Godavari basin from the given data
for the year 1990. Area of the basin is 5260km2
. [16]
Month Inflow into Rainfall over Average Evapotranspiration
the basin (mm3
) the basin(mm) (mm3
)
Jan 4.09 4.67 81
Feb 14.70 17.80 81
Mar 13.20 8.96 81
Apr 9.8 24.01 81
May 3.33 57.30 81
June - 7.34 162
July - 7.72 162
Aug - 21.08 162
Sep 21.4 48.9 162
Oct 21.7 204.6 162
Nov 21.86 92.4 81
Dec 11.47 5.42 81
4
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5. JNTUW
ORLD
Code No: 07A80102 R07 Set No. 1
IV B.Tech II Semester Examinations,April/May 2012
GROUND WATER DEVELOPMENT AND MANAGEMENT
Civil Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. What are the Site Characteristics and Design Guidelines to be followed while de-
signing percolation tank? [16]
2. (a) Explain various advantages of subsurface reservoirs over surface reservoirs.
(b) Explain various beneficial effects of conjunctive use in canal commands. [8+8]
3. In a confined aquifer, a well of diameter 20 cms and radius of influence 1.2 kms
maintains a steady piezometric head. 75 m away from the well axis a head gradient
of 5.678 × 103
is noted in the radial direction:
(a) Compute the drawdown ata the well face.
(b) If pumping discharge is 2450 m3
/day, compute the aquifer transmissivity.
(c) If the piezometric head at a distance of 100m is measured as 44m, what will
be its value 250 m away from the well? [16]
4. A confined stratified aquifer has a total thickness of 12 m and is made up to
three layers. The bottom layer has a coefficient of permeability of 30 m/day and
a thickness of 5.0 m. The middle and top layers have permeability of 20 m/day
and 45 m/day respectively and are of equal thickness. Calculate the transmissivity
of the confined aquifer and the equivalent permeability, if the flow is along the
stratification. [16]
5. The diameter of a pumping well is 10 cm, location of the observation well is
16 m and rate of pumping is 2500 lpm. Find the parameters S and T of a confined
aquifer where test pumping gave the following information.
Drawdown after one hour of pumping = 3m
Drawdown after four hours of pumping = 4m. [16]
6. Following are the data obtained in a refraction shooting. Determine the depth to
the water table: [16]
5
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6. JNTUW
ORLD
Code No: 07A80102 R07 Set No. 1
Geophone (no.) Geophone (no.) Time of first arrival (m/sec)
1 20 100
2 40 200
3 60 300
4 80 400
5 100 500
6 120 590
7 140 620
8 160 660
9 180 700
7. Derive a time variant regional groundwater flow equation for confined and phreatic
aquifers involving recharge. Discuss the various types of recharge terms that can
be grouped together, and a method for their estimation. [16]
8. Compute the aquifer head at a point P above sea level for the two coastal aquifers
given in the figure 1. Given ρs = 1025kg/m3
, ρf = 1000kg/m3
. [16]
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Code No: 07A80102 R07 Set No. 1
Figure 1:
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8. JNTUW
ORLD
Code No: 07A80102 R07 Set No. 3
IV B.Tech II Semester Examinations,April/May 2012
GROUND WATER DEVELOPMENT AND MANAGEMENT
Civil Engineering
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. Derive the discharge equation for steady state artesian flow along with a neat sketch
and assumptions adopted. [16]
2. (a) Differentiate between surface water and subsurface water.
(b) Describe the groundwater resources of India and its utilization. [8+8]
3. (a) When actually sea water intrusion takes place? How would you locate the
fresh water-sea water interface?
(b) Indicate the practical methods to halt and abate sea-water intrusion in the
Chennai Coastal environs? [8+8]
4. In a Schlumberger electrical resistivity investigation, the spacing of the current and
potential electrodes was as follows:
Current electrode spacing (m) Current electrode spacing (m)
5 0.5
100 1.5
500 24
If the amount of current passed in the ground was 628 mA and the corresponding
voltage difference readings were 969.2, 175, and 895 milli-volts, for the respective
spacings, compute the apparent resistivity values for the three sets. Discuss why
they are different. What qualitative inference can you draw from it? What type of
master curve will be used to interpret the field VES curve with the above data?
[16]
5. (a) Give the hydrologic budget equations, separately, for the recharge area and
discharge area of a basin.
(b) An average decline of 2m in the water table is noticed, over an area of 50sq.
km. due to withdrawal of 15 × 106
m3
of water from the phreatic aquifer
during a period of drought. Subsequently, rainfall of 1200 mm occurred and
the water levels rose by an average of 1.6m. Determine the specific yield of
the materials in the zone of water-level fluctuation and the rainfall-infiltration
factor. Assume that the specific yield of the materials is uniform. [8+8]
6. Two observation wells located at a distance of 495 and 575 m respectively from the
production well measure a drawdown of 66 and 56 cms respectively after 5 hours
of pumping at the rate of 3500 m3
/day. The discharging well fully penetrates the
confined aquifer. Compute the parameters T and S and the radius of influence of
the well after 1 day. Assume Jacob’s drawdown method is applicable. [16]
8
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9. JNTUW
ORLD
Code No: 07A80102 R07 Set No. 3
7. Show that for a pumping well located at a distance a from a recharge source, the
drawdown is almost the same as that of the circular island aquifer of radius 2a.
[16]
8. Explain the following artificial methods along with its design:
(a) Induced recharge methods
(b) Well method. [16]
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