JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III GROUND WATER DEVELOPMENT AND MANAGEMENT Previous Question Paper (August - 2022 - R16)
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Main
Explain the Groundwater Potential theory and write the expression for velocity potential. Write a steady groundwater flow in a anisotropic formation.
Answer
The Groundwater Potential Theory is based on the concept that groundwater flow in a porous medium can be described by a scalar function, known as the velocity potential, provided the flow is irrotational. This simplifies the analysis of complex flow patterns by reducing the vector velocity field to the gradient of a single potential function.
The expression for velocity potential (φ) is defined such that the velocity vector v is the negative gradient of the potential:
For steady groundwater flow in an anisotropic formation, where hydraulic conductivities differ in the x, y, and z directions (Kx, Ky, Kz), the governing equation is derived from Darcy's Law and the continuity equation:
where h is the hydraulic head.
Write down the stages of groundwater development in the country GEC.
Answer
The Ground Water Estimation Committee (GEC) categorizes groundwater development stages based on the ratio of annual groundwater extraction to the annual extractable groundwater resource. The stages are classified as follows:
- Safe: Stage of groundwater development is less than or equal to 70%.
- Semi-Critical: Stage of groundwater development is between 70% and 90%.
- Critical: Stage of groundwater development is between 90% and 100%.
- Over-Exploited: Stage of groundwater development exceeds 100%.
- Saline: Areas where the groundwater is not suitable for potable or irrigation use due to high salinity, regardless of the development stage.
Explain in brief, with equations the aquifer parameters.
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On a particular day, in a field well the initial water table was observed 6 m below the ground level. The water table was lowered 8 m below the ground surface when quantity of 4,00,000 m3 of water was pumped per square kilometer. Compute the specific yield, specific retention of soil assuming the porosity as 30% and there are no other losses.
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What is ground water movement? Explain the Darcy’s law for laminar flow and its limitations.
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In a homogeneous isotropic confined aquifer has a constant thickness of 20 m, effective porosity of 20% and permeability of 15m/day, two observation wells 1200 m apart indicate piezometric heads of 5.4 m and 3.0 m above MSL respectively. Assuming uniform flow, average grain diameter of sand 1 mm and kinematic viscosity (v) of water = 0.01 cm/s, state (i) whether Darcy’s law is applicable? (ii) what is the average flow velocity in pores?
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What is permeability? Explain the determination of permeability by constant head permeameter.
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A constant head permeameter was used to determine the permeability, following observations were recorded:
- Dia. of soil sample = 7 cm
- Length of soil sample = 3.5 cm
- Hydraulic head = 35 cm
- Volume of water flow = 200 cc in one minute and fifty seconds
Determine the hydraulic conductivity of soil, assuming G = 0.85.
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Write down assumptions in Dupit’s equation and Theim’s equation.
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A confined stratified aquifer has a total thickness of 12 m and is made up of three layers. The bottom layer has a coefficient of permeability of 30 m/day and a thickness of 5 m. The middle and top layers have permeability of 20 m/day and 45 m/day respectively and are of equal thickness. Calculate the transmissibility of the confined aquifer and the equivalent permeability, if the flow along the stratification.
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Explain Chow’s method of determining hydraulic properties of the aquifers through pumping test.
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A 30 cm well penetrates an aquifer of transmissibility of 2 × 105 lpd/m and a storage coefficient of 0.005. What pumping rate could be adopted so that the drawdown will not exceed 10 m within the subsequent two years of drought?
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Why do we recharge ground water artificially? Explain the significance.
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Draw a flow chart to identify the suitable sites for artificial recharge zones using Remote Sensing and GIS technology.
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How do you develop a tube well after its construction?
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What is meant by conjunctive use of water? State its benefits.
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