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Question 1
ప్రశ్న 1
Which expression correctly defines the porosity n of a soil or rock sample?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Porosity measures the fraction of the bulk material occupied by void spaces. It is defined as the volume of voids divided by the total bulk volume of the soil or rock. Porosity is dimensionless and is commonly expressed either as a decimal fraction or percentage. It indicates potential void space but does not state how much water will drain by gravity. Therefore Option B is correct.
వివరణ:
Question 2
ప్రశ్న 2
A saturated soil sample has a total bulk volume of 0.50 m³ and contains 0.18 m³ of void space. What is its porosity?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Porosity is the ratio of void volume to total bulk volume. Thus n = 0.18/0.50. This gives n = 0.36. Expressed as a percentage, the porosity is 36 percent. Therefore Option C is correct.
వివరణ:
Question 3
ప్రశ్న 3
Which statement best defines specific yield Sy of a saturated aquifer material?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Specific yield represents the portion of a saturated formation's bulk volume that can drain under gravity. It is therefore a measure of drainable groundwater storage. Some pore water remains held by capillary and molecular forces and is not included in specific yield. Specific yield is dimensionless and is normally less than porosity. Therefore Option A is correct.
వివరణ:
Question 4
ప్రశ్న 4
Which definition most accurately describes specific retention Sr?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
When a saturated soil or rock drains under gravity, some water remains attached to grains and retained in small pores. This retained amount is represented by specific retention. It is expressed as retained water volume divided by total bulk volume. Fine-grained materials can have relatively large specific retention because capillary and surface forces are strong. Therefore Option D is correct.
వివరణ:
Question 5
ప్రశ్న 5
Under the standard volumetric partition of an initially saturated sample after gravity drainage, which relation is correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The water that initially occupied the pore volume can conceptually be divided into water that drains by gravity and water that remains retained. These two fractions are represented by specific yield and specific retention. Under the standard groundwater-storage definition, their sum corresponds to the porosity of the saturated sample. Thus n = Sy + Sr. Therefore Option B is correct.
వివరణ:
Question 6
ప్రశ్న 6
An aquifer material has porosity 0.38 and specific yield 0.24. What is its specific retention under the standard relation n = Sy + Sr?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Specific retention is obtained by rearranging the storage relation. Thus Sr = n - Sy. Substituting gives Sr = 0.38 - 0.24 = 0.14. This means 14 percent of the bulk volume remains occupied by water retained against gravity drainage under the stated idealization. Therefore Option C is correct.
వివరణ:
Question 7
ప్రశ్న 7
Two saturated materials have similar total porosity, but one is fine clay and the other is well-sorted coarse sand. Which statement is generally most reasonable?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Total porosity describes the amount of void space but does not determine how easily water drains from that void space. Fine clay can contain substantial pore water while retaining much of it against gravity. Coarser materials generally permit a greater proportion of their stored water to drain. Consequently similar porosity values can coexist with very different specific yields and hydraulic conductivities. Therefore Option A is correct.
వివరణ:
Question 8
ప్రశ్న 8
An unconfined aquifer covers 2 km² and has specific yield 0.20. If its water table declines uniformly by 1.5 m and elastic storage is neglected, approximately how much groundwater is released from storage?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a water-table decline, gravity drainage is approximately Sy times area times water-table change. The area is 2 km², or 2,000,000 m². Therefore the released volume is 0.20 × 2,000,000 × 1.5. This equals 600,000 m³. Hence Option D is correct.
వివరణ:
Question 9
ప్రశ్న 9
Which description of hydraulic conductivity K is most accurate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Hydraulic conductivity describes the ease with which a particular fluid moves through a porous medium under a hydraulic gradient. Its dimensions are length per unit time, such as metres per day or metres per second. It depends on both the pore structure of the medium and fluid properties such as viscosity and density. It is therefore not identical to intrinsic permeability. Hence Option B is correct.
వివరణ:
Question 10
ప్రశ్న 10
Which statement correctly distinguishes intrinsic permeability k from hydraulic conductivity K?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Intrinsic permeability characterizes the pore geometry and connectivity of the porous medium itself. It has dimensions of area, or length squared. Hydraulic conductivity additionally depends on fluid density and viscosity as well as intrinsic permeability. For this reason the same porous medium can have different hydraulic conductivities for different fluids or fluid temperatures. Therefore Option C is correct.
వివరణ:
Question 11
ప్రశ్న 11
For the same porous medium, fluid density and gravity, the dynamic viscosity of the flowing fluid is reduced to one-half of its original value. From K = kρg/μ, how does hydraulic conductivity change?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Hydraulic conductivity is inversely proportional to dynamic viscosity when intrinsic permeability, density and gravity remain fixed. Halving the viscosity therefore doubles the value of K. The intrinsic permeability of the porous material itself has not changed in this situation. The change arises entirely from the changed fluid property. Therefore Option A is correct.
వివరణ:
Question 12
ప్రశ్న 12
What is transmissivity T of an aquifer?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Transmissivity is an aquifer-scale transmission property. For a homogeneous aquifer of hydraulic conductivity K and saturated thickness b, transmissivity is T = Kb. Its units are length squared per time, such as m²/day. A thicker aquifer can therefore have greater transmissivity than a thinner aquifer even when their hydraulic conductivities are identical. Therefore Option D is correct.
వివరణ:
Question 13
ప్రశ్న 13
A homogeneous confined aquifer has hydraulic conductivity 20 m/day and saturated thickness 15 m. What is its transmissivity?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a homogeneous aquifer, transmissivity is T = Kb. Substituting K = 20 m/day and b = 15 m gives T = 20 × 15. This equals 300 m²/day. The dimensional result is length squared per time, as required for transmissivity. Therefore Option B is correct.
వివరణ:
Question 14
ప్రశ్న 14
A layered aquifer consists of a 10 m layer with K = 5 m/day and a 20 m layer with K = 15 m/day, with flow parallel to the layers. What is the total transmissivity across the full saturated thickness?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For horizontal flow parallel to layered strata, the transmissivity contributions of the individual layers can be summed. The first layer contributes 5 × 10 = 50 m²/day. The second contributes 15 × 20 = 300 m²/day. Total transmissivity is therefore 50 + 300 = 350 m²/day. Hence Option C is correct.
వివరణ:
Question 15
ప్రశ్న 15
A homogeneous aquifer has transmissivity 600 m²/day and saturated thickness 20 m. What is its hydraulic conductivity?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a homogeneous aquifer, T = Kb. Rearranging gives K = T/b. Thus K = 600/20 = 30 m/day. The calculation properly converts the aquifer-scale transmissivity to the corresponding material hydraulic conductivity. Therefore Option A is correct.
వివరణ:
Question 16
ప్రశ్న 16
Which statement correctly defines storage coefficient or storativity S of an aquifer?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Storativity quantifies the storage response of an aquifer to changes in hydraulic head. It is defined as water released from or added to storage per unit horizontal area per unit head change. Because volume divided by area and head has no remaining dimension, storativity is dimensionless. The physical mechanism differs between confined and unconfined systems. Therefore Option B is correct.
వివరణ:
Question 17
ప్రశ్న 17
Which statement about specific storage Ss is correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Specific storage describes the elastic storage response per unit volume of saturated aquifer material. It accounts for compressibility of the aquifer skeleton and the groundwater. Its dimensions are inverse length because stored-water volume per bulk volume is dimensionless and is divided by a head change having dimensions of length. It is therefore commonly expressed in units such as m⁻¹. Hence Option D is correct.
వివరణ:
Question 18
ప్రశ్న 18
A confined aquifer has specific storage Ss = 2.0 × 10^-5 m^-1 and thickness 30 m. What is its storativity?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a confined aquifer of uniform specific storage, S = Ss b. Substituting gives S = 2.0 × 10^-5 × 30. The result is 6.0 × 10^-4. Storativity is dimensionless because the inverse-length unit of specific storage is cancelled by aquifer thickness. Therefore Option C is correct.
వివరణ:
Question 19
ప్రశ్న 19
What is the principal source of water released from storage when hydraulic head declines in a fully confined aquifer?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A confined aquifer remains saturated while its hydraulic head changes. Water is therefore not released mainly by a water table physically draining through the pore spaces. Instead, declining pressure causes slight expansion of groundwater and compression of the aquifer skeleton. These elastic effects are represented through specific storage and confined-aquifer storativity. Therefore Option A is correct.
వివరణ:
Question 20
ప్రశ్న 20
Why is the storage response of an unconfined aquifer commonly approximated by its specific yield for substantial water-table changes?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
When the water table in an unconfined aquifer falls, previously saturated pores drain by gravity. This drainage is quantified by specific yield and usually releases far more water than elastic compression and water expansion. Elastic storage still exists and is not literally zero. For many engineering calculations involving appreciable water-table movement, storativity is therefore approximated by specific yield. Hence Option B is correct.
వివరణ:
Question 21
ప్రశ్న 21
An unconfined aquifer extends over a rectangular area 500 m by 400 m and has specific yield 0.18. If the water table declines uniformly by 2.0 m, what groundwater volume is released by gravity drainage, neglecting elastic storage?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The aquifer area is 500 × 400 = 200,000 m². The volume of material dewatered by a 2 m water-table decline is 400,000 m³. Multiplying this by specific yield gives 0.18 × 400,000. The result is 72,000 m³ of gravity-drained groundwater. Therefore Option D is correct.
వివరణ:
Question 22
ప్రశ్న 22
A confined aquifer covers 1.0 km² and has storativity S = 5 × 10^-4. If the piezometric head declines uniformly by 10 m, what volume of water is released from storage?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a confined aquifer, released storage volume is S times aquifer area times head decline. The area is 1.0 km², or 1,000,000 m². Thus V = 5 × 10^-4 × 1,000,000 × 10. The result is 5000 m³. Therefore Option C is correct.
వివరణ:
Question 23
ప్రశ్న 23
Which combination of aquifer properties and dimensions is correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Porosity and specific yield are ratios of volumes and are therefore dimensionless. Hydraulic conductivity has dimensions of velocity, L/T. Multiplying hydraulic conductivity by aquifer thickness gives transmissivity with dimensions L²/T. Specific storage has dimensions 1/L, while multiplying it by thickness gives dimensionless confined storativity. Therefore Option A is correct.
వివరణ:
Question 24
ప్రశ్న 24
Two homogeneous confined aquifers have the same hydraulic conductivity of 10 m/day, but Aquifer X is 10 m thick and Aquifer Y is 20 m thick. How do their transmissivities compare?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Transmissivity is T = Kb for a homogeneous aquifer. Aquifer X therefore has T = 10 × 10 = 100 m²/day. Aquifer Y has T = 10 × 20 = 200 m²/day. Thus doubling saturated thickness at unchanged hydraulic conductivity doubles transmissivity. Therefore Option B is correct.
వివరణ:
Question 25
ప్రశ్న 25
Consider the following statements about aquifer properties: I. Total porosity does not by itself equal the volume fraction that will drain by gravity. II. Specific yield is normally less than porosity because some water is retained after gravity drainage. III. Hydraulic conductivity depends on both porous-medium and fluid properties, whereas intrinsic permeability is a property of the medium. IV. For a uniform confined aquifer, transmissivity is Kb and storativity is Ss b. Which option is correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Statement I correctly distinguishes total pore volume from drainable groundwater storage. Statement II follows from the existence of specific retention, since some water remains held against gravity. Statement III correctly separates hydraulic conductivity from intrinsic permeability. Statement IV gives the standard thickness-integrated relations for a uniform confined aquifer. Therefore all four statements are correct and Option D is the valid answer.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: B. Volume of voids divided by total bulk volume సమాధానం: B.
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Question 2 ప్రశ్న 2Answer: C. 36% సమాధానం: C.
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Question 3 ప్రశ్న 3Answer: A. The volume of water that drains by gravity divided by the total bulk volume of the material సమాధానం: A.
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Question 4 ప్రశ్న 4Answer: D. The volume of water retained against gravity drainage divided by the total bulk volume of the material సమాధానం: D.
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Question 5 ప్రశ్న 5Answer: B. n = Sy + Sr సమాధానం: B.
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Question 6 ప్రశ్న 6Answer: C. 0.14 సమాధానం: C.
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Question 7 ప్రశ్న 7Answer: A. The clay can have much lower specific yield because a larger fraction of its pore water is retained by capillary and surface forces సమాధానం: A.
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Question 8 ప్రశ్న 8Answer: D. 600,000 m³ సమాధానం: D.
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Question 9 ప్రశ్న 9Answer: B. It characterizes the ability of a porous medium containing a specified fluid to transmit that fluid and has dimensions of length per time సమాధానం: B.
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Question 10 ప్రశ్న 10Answer: C. Intrinsic permeability is a property of the porous medium, whereas hydraulic conductivity also depends on properties of the flowing fluid సమాధానం: C.
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Question 11 ప్రశ్న 11Answer: A. It approximately doubles సమాధానం: A.
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Question 12 ప్రశ్న 12Answer: D. The ability of the full saturated aquifer thickness to transmit water through a unit-width section under a unit hydraulic gradient సమాధానం: D.
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Question 13 ప్రశ్న 13Answer: B. 300 m²/day సమాధానం: B.
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Question 14 ప్రశ్న 14Answer: C. 350 m²/day సమాధానం: C.
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Question 15 ప్రశ్న 15Answer: A. 30 m/day సమాధానం: A.
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Question 16 ప్రశ్న 16Answer: B. The volume of water released from or taken into storage per unit aquifer surface area per unit change in hydraulic head సమాధానం: B.
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Question 17 ప్రశ్న 17Answer: D. It is the volume of water released from storage per unit bulk aquifer volume per unit decline in hydraulic head and has dimensions of inverse length సమాధానం: D.
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Question 18 ప్రశ్న 18Answer: C. 6.0 × 10^-4 సమాధానం: C.
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Question 19 ప్రశ్న 19Answer: A. Elastic expansion of water and compression of the aquifer skeleton సమాధానం: A.
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Question 20 ప్రశ్న 20Answer: B. Because gravity drainage and filling of pores as the water table moves usually dominate over the much smaller elastic-storage component సమాధానం: B.
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Question 21 ప్రశ్న 21Answer: D. 72,000 m³ సమాధానం: D.
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Question 22 ప్రశ్న 22Answer: C. 5000 m³ సమాధానం: C.
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Question 23 ప్రశ్న 23Answer: A. Porosity—dimensionless; specific yield—dimensionless; hydraulic conductivity—L/T; transmissivity—L²/T; specific storage—1/L; storativity—dimensionless సమాధానం: A.
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Question 24 ప్రశ్న 24Answer: B. Aquifer Y has twice the transmissivity of Aquifer X సమాధానం: B.
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Question 25 ప్రశ్న 25Answer: D. I, II, III and IV సమాధానం: D.