JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III GROUND WATER DEVELOPMENT AND MANAGEMENT Previous Question Paper (May - 2019 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
Explain the terms Specific yield and Specific retention
Answer
Specific yield (Sy) is the ratio of the volume of water that a saturated rock or soil will yield by gravity to the total volume of the rock or soil. Specific retention (Sr) is the ratio of the volume of water that a rock or soil can retain against the pull of gravity to its total volume.
At certain point in an unconfined aquifer of 3 km2 area, the water table was at an elevation of 102.00 m. Due to natural recharge in a wet season, its level rose to 103.20 m. A volume of 1.5 Mm3 of water was then pumped out of the aquifer causing the water table to reach a level of 101.20 m. Assuming the water table in the entire aquifer to respond in a similar way, estimate (i) the specific yield of the aquifer and (ii) the volume of recharge during the wet season.
Answer
Given: Area (A) = 3 km2 = 3 x 106 m2. Rise in water table due to recharge = 103.20 - 102.00 = 1.20 m. Fall in water table due to pumping = 103.20 - 101.20 = 2.00 m. Volume pumped (Vp) = 1.5 Mm3 = 1.5 x 106 m3.
- Specific yield (Sy) = Volume pumped / (Area x drop in water table) = 1.5 x 106 / (3 x 106 x 2.00) = 0.25.
- Volume of recharge (Vr) = Area x rise in water table x Sy = 3 x 106 x 1.20 x 0.25 = 0.9 x 106 m3 = 0.9 Mm3.
Write a short note on transmissivity.
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What are the assumptions involved in differential equation governing ground water flow in three dimensions using Darcy’s law.
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List the practices that are widely applied using Theim’s equation.
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List out assumptions involved in Dupit’s equation.
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Discuss in brief about caliper logging.
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What is the purpose of artificial recharge of ground water?
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List out advantages of conjuctive use of surface and ground water resources.
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Write a short note on upconing of saline water.
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Part B
With a neat sketch describe the various types of aquifers.
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Explain how the rock properties affect the Ground water.
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How would you classify saturated formations?
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How would you explain flow in relation to Ground water contours?
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A field test for permeability consists in observing the time required for a tracer to travel between two observation wells. A tracer was found to take 12 h to travel between two wells 60 m apart when the difference in the water- surface elevation in them was 0.6 m. The mean particle size of the aquifer was 2 mm and the porosity of the medium 0.3. If γ = 0.01 cm2/s. Estimate (a) the coefficient of permeability and intrinsic permeability of the aquifer, and (b) the Reynolds number of the flow.
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Describe a procedure by using Jacob’s method to calculate the aquifer parameters of a confined aquifer by using the well pumping test data.
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During the recuperation test of a 4.0 m open well a recuperation of the depression head from 2.5 m to 1.25 m was found to take place in 90 minutes. Determine the (a) Specific capacity per unit well area, and (b) yield of the well for a safe drawdown of 2.5 m (c) What would be the yield from a well of 5.0m diameter for a drawdown of 2.25 m?
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Describe in detail the exploration of ground water by electrical resistivity method.
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Explain artificial recharge of ground water through stream-channel method and Ditch – and – Furrow method.
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Elaborate various methods used in constructing shallow wells? Explain in brief one of the method.
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What are the commonly used methods to control saline water intrusion? Explain them briefly.
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