University of Pune 2008 B.E Civil Engineering Irrigation Engineering - Question Paper
Seat No.:___
December-2008
l ime : 3 Hours] (Max. Marks : 100
(10:30 A.M. tol : 30 P.M.)
Instructions : (1) Answer to each section must be written in separate answer books.
(2) Assume your own suitable data if required.
(3) Figure to the right indicate full marks.
(4) Calculation aid is permitted.
Section -1
1. (a) What is Assessment of irrigation water ? Why it is required ? In which situation
volumetric method is adopted ? What are its shortcomings ? 18
(b) Define the following terms :
Field capacity, water conveyance efficiency, Hygroscopic water, permanent wilting point, water application efficiency and outlet factor.
(c) After how many days will you supply water to soil in order to ensure efficient irrigation of the given crop, if
(i) Field capacity of soil = 30%
(ii) Pennanent wilting point = 15%
(iii) Density of soil = 1.5 g/cm3
(iv) Effective depth of root zone = 80 cm
(v) Daily consumptive use of water for the given crop = 10 mm.
OR
(a) Under what conditions sprinkler method of irrigation is preferred ? Write down the advantages and disadvantages of this method.
(b) Discuss in brief the benefits and ill effects of irrigation.
(c) The base period, Duty of water and area under irrigation for various crops under a canal system are given in table. The total culturable command area is 40,000 Ha.
It the losses in the reservoir and canals are respectively 15% and 25% determine the reservoir capacity.
|
Crops |
Wheat |
Sugarcane |
Cotton |
Rice |
|
Base period in (days) |
120 |
320 |
180 |
120 |
|
Duty (ha/cumecs) |
1900 |
1500 |
1400 |
900 |
|
% Area irrigated |
45% |
25% |
10% |
20% |
2. (a) What do you understand by the elementary profile of the gravity dam ? Derive the expression for determining the base width of such a dam based on (i) Stress criteria and (ii) Sliding criteria. 16
( b) Explain various methods of reducing seepage through earthen dams.
(c ) Fig.-1 shows the section of gravity dam (Non Overflow portion) built of concrete. Calculate (Neglecting earthquake effects)
(i) The maximum vertical stresses at the heel and toe of the dam.
(ii) The major principal stresses at roe of the dam.
iii) Hie intensity of shear stress on a hoiizoniai pljne ne;r the toe Assume weight of concrete = 24 kN/m3
OR
How wouid you proceed to determine phreatic line through homogeneous earth dams provided with a horizontal filter ?
(a)
(b)
(c)
What do you mean by Gravity dam ? Enlist with sketch the various forces and discuss uplift pressure force in detail.
Following data refers to homogenous earth dam :
Top width = 4m
Head of water u/s = 16 m
u/s and d/s slope = 2.5 H: IV and 2H : IV respectively
Free board = 2.5 m
Horizontal filter 37 m from d/s toe.
Coefficient of permeability K - 0.008 cm/sec.
Calculate seepage per meter length of dam.
Write short notes on (any four): 16
(i) Galleries in Gravity dam
(ii) Crop Rotation
(iii) Rock fill dam
(iv) Bucket type energy dissipation device
(v) Ogee spillway
Section - II
(a) Draw a neat sketch of diversion headworks and explain functions of each component. 18
4.
(b) What are the methods of controlling entry of silt at the headworks of a canal ?
(c) Explain the Blighs Creep theory for the design of impervious floor on permeable foundations. What are the limitations of this theory ?
OR
(a) What do you understand by exit gradient ? How would you compute it ? What is its significance ?
(b) Discuss briefly the causes of failure of hydraulic structures founded on pervious foundation.
(c) Design an irrigation canal to carry a discharge of 5 cumecs. Take critical velocity ratio = 1, bed slope of canal 0.2 m per km and Chezys constant C = 42.85.
Use Kennedys approach
(a) Differentiate between : 16
5.
(i) Weir and Barrage
(ii) Silt excluder and Silt ejector
(b) Explain Khoslas method of independent variable for weir design. How corrections are applied for (i) thickness of floor (ii) inclination of floor (iii) interface of pile.
(c) What is initial and final regime conditions of an alluvial channel according to Lacey?
OR
(a) Explain various types of canal according to various classification systems.
(b) Describe with the help of sketches, the various types of cross-drainage works.
(c) Design an irrigation canal using Laceys theory for the following data :
Discharge - 45 cumecs
Silt factor f = 1
Side slope = J: 1
6. Write short notes on (any four)
(i) Bandhara irrigation
(ii) Canal falls
(iii) Causes of water logging
(iv) Balancing depth of canal
(v) Head Regulator
5337
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Attachment: |
| Earning: Approval pending. |
