Irrigation Engineering - Dec 16

Civil Engineering (Semester 7)

Total marks: 80
Total time: 3 Hours
INSTRUCTIONS
(1) Question No.1 is compulsory.
(2) Attempt any three questions from remaining five questions.
(3) Assume any suitable data where ever required.
(4) Figures to the right indicate full marks.

Q1) Solve any four from the following.

• a) Discuss briefly the various techniques used for the distributing water in the farms.
• b) What is meant by "Flow duty" and "Quantity duty"? Describe briefly factors affecting duty.
• c) What is Precipitation? Explain the various types of precipitation.
• d) Differentiate between confined and unconfined aquifer with neat sketch.
• e) Discuss the factors which are considered for the selection of site for a proposed dam.

(20 marks)

2(a) Write a short note on irrigation efficiencies. (6 marks)

2(b) Explain recording type rain gauge with neat sketches. (6 marks)

2(c) Determine the reservoir capacity for:
Command area of 40,000 ha , canal losses= 10% and reservoir losses= 10% Base period, outlet factor and intensity of irrigation are as under:

(8 marks)

3(a) What do you understand by Catchment area and Runoff? Explain the various factors that influence the runoff from a catchment area. (8 marks)

3(b) The following are the ordinates of 12 hour unit hydrograph.

If successive 12 hour rainfall excesses are 1.5 cm, 3.0 cm and 0.75 cm for the catchment, plot the resulting flood hydrograph on a graph sheet and mark the lag time and flow expected for the river. (8 marks)

3(c) Define "Storage coefficient" and "Transmissibility". (4 marks)

4(a) Write a short note on Reservoir Sedimentation and Explain the methods to control it. (6 marks)

4(b) Explain the various forces acting on gravity dam with neat sketches. (6 marks)

4(c) A 60cm diameter well is being pumped at a rate of 1360 lit/minute. Measurements in the nearby test well were made at the same time as follows: At a distance of 6m from the well being pumped, the drawdown was 6m and at 15m the drawdown was 1.5m. The bottom of the well is 90m below the ground water table. (a) Find out the coefficient of permeability. (b) If all the observed points were on the dupuits curve, what was the draw down in the well during pumping? (c) what is the rate at which water can be drawn from this well. (8 marks)

5(a) What are the causes offailure of Earthen Dam? Explain in detail with neat sketches. (10 marks)

5(b) A concrete gravity dam has maximum water level 305.0m, bed level 225.0m, top R.L of dam 309.0m, d/s face slope starts at R.L 3000.0m, d/s slope 2:3, tail water is nil, upstream face of dara is vertical, center line of drainage gallery is 8m d/s of u/s face, uplift pressure is 100% at the heel, 50% at the line of gallery and zero at toe, weight of concrete is 2.4 t/m$^3$. Considering only weight, water pressure and uplift , determine (i) Maximum vertical stresses at toe and heel of the dam, (ii) Major principal stresses at the toe of dam, and (iii) Intensity of shear stress on a horizontal plane near the toe. (10 marks)

Q6) Write a short note on following:

• a) Arch and Buttress Dam
• b) Cross Drainage works
• c) Canal Regulation works
• d) Canal Lining and Water Logging

(20 marks)