JNTU
JNTU B.Tech IV IRRIGATION AND HYDRAULIC STRUCTURES Previous Question Paper (January/February - 2023 - R18)
Note: i) Question paper consists of Part A, Part B.
ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions.
iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
PART - A
List 4 factors that influence sediment inflow into reservoirs.
Answer
The four primary factors that influence sediment inflow into reservoirs are:
- Catchment Area Characteristics: The size, shape, and topography of the drainage basin significantly dictate the volume of runoff and potential for erosion.
- Soil and Geological Conditions: The erodibility of the soil, type of rock, and geological stability within the catchment determine the amount of sediment generated.
- Vegetation Cover: Dense vegetation acts as a protective layer that reduces surface erosion and traps sediment, whereas deforestation increases sediment yield.
- Climatic Factors: The intensity, duration, and frequency of rainfall directly affect the rate of soil erosion and the transport capacity of the river system.
What is trap efficiency and its importance?
Answer
Trap efficiency is defined as the ratio of the quantity of sediment deposited in a reservoir to the total quantity of sediment entering the reservoir, usually expressed as a percentage. It represents the reservoir's capacity to retain incoming sediment load rather than allowing it to pass through the spillway or outlets.
Its importance lies in the following areas:
- It is the primary factor in determining the useful life of a reservoir, as sediment deposition directly reduces the active storage capacity over time.
- It is essential for calculating the rate of reservoir sedimentation, which informs the design of dead storage and the planning of long-term water management strategies.
- It helps engineers estimate the downstream impact of sediment trapping, such as potential channel degradation or changes in river morphology caused by the release of sediment-starved water.
List factors considered for selection of site for a dam.
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Show forces acting on a gravity dam with sketch.
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Sketch Rockfill dam and indicate its components.
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What is spillway? List factors affecting its capacity.
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What is the importance of exit gradient?
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List causes for failure of weirs on permeable foundations.
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What is a canal escape? Where is it provided?
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Sketch Ogee fall? Where do you prefer this fall.
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PART - B
The quantity of water flowing in a river during each successive month is given below in Mm3. 4.2, 5.1, 8.5, 27.5, 45.3, 30.6, 14.2, 11.1, 10.2, 9.3, and 8.8. Determine the minimum capacity of a reservoir, if the above water is to be drawn off at a uniform rate and there should be no loss by flow over the spillway.
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Discuss the various investigations required for reservoir planning.
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Explain how probable life of reservoir is estimated.
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Following data is collected from a concreted dam. Max water level = 305 m, BL of river = 225 m, Crest level = 309 m, D/S face slope starts at 300m, D/S slope = 2 : 3, C/L of drainage galleries at 8m d/s of u/s face, Uplift pressures at heal = 100% , Uplift pressures at toe = 0%, Uplift pressures at heal = 50%, Density of concrete = 2400 kg/m3. Assume no tail water; Foundation condition – Inferior condition with limestone. Consider self-weight, hydrostatic pressure and uplift pressure only. Design a concrete beam.
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What do you understand by the elementary profile and a practical profile of gravity dam? How is the limiting height of a gravity dam calculated?
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Explain Construction and Contraction joints in gravity dam.
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Explain with a neat sketch the Swedish slip circle method for stability analysis of earth dam.
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Describe hydraulic and seepage failure of earthen dam.
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Compute the discharge over an ogee weir with coefficient of discharge equal to 2.4 at a head of 2 m. The length of spillway is 100 m. The weir crest is 8 m above the bottom of the approach channel having the same width as that of the spillway. Consider velocity of approach.
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Draw sectional view of a typical barrage. Compare different aspects of a weir and barrage.
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Explain Khosla theory differs from Bligh’s Theory with respect to design of weirs on permeable foundations.
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A weir with a vertical drop has the following details: Length of the weir = 40m, Height of the weir above low water = 2 m, Height of falling shutter = 0.6 m, Top width of the weir = 2 m, Bottom width of the weir = 3.5 m. Design the length and thickness of aprons and sketch the cross section of the weir.
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Differentiate between cross regulator (CR) and head regulator (HR). Explain the design principles of CR and HR.
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Write design procedure for Sarda type of fall.
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Present a detailed classification Cross Drainage works. Draw a typical sketch and explain the constructional details of aqueduct.
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