VTU Civil Engineering (Semester 5)
Hydrology & Irrigation Engineering
December 2014
Total marks: --
Total time: --
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1 (a) Explain in brief different types of precipitation.
8 M
1 (b) How do you estimate the average depth of precipitation by Thiessen polygon method?
5 M
1 (c) The average annual rainfall in cm at 4 existing rain gauge stations are 105, 79, 70 and 66cm respectively. If the average depth of rainfall over the basin is to be estimated within 10% error. Determine the additional number of rain gauge required.
7 M

2 (a) Define evaporation. What are the factors affecting evaporation?
6 M
2 (b) List the methods of estimation of evapotranspiration. Discuss Blaney-Criddle method.
6 M
2 (c) For small catchment the infiltration rate at the beginning of a storm was observed 90mm/hr and decreased exponentially to a constant rate of 8mm/hr after 2 1/2 hour. The total infiltration during 2 1/2 hr was 50mm. Develop Horton's equation and determine the infiltration rate at 30 min.
8 M

3 (a) With the aid of neat sketch show the various components of an observed flood hydrograph.
8 M
3 (b) What are the uses and application of unit hydrograph.
4 M
3 (c) Following are the ordinates of a 3-hr unit hydrograph. Derive the ordinate of a 6hr unit hydrograph:
Time in hour 0 3 6 9 12 15 18 21 24
Ordinates of 3 hr
unit hydro graph
0 1.5 4.5 8.6 12.0 9.4 4.6 2.3 0.8
8 M

4 (a) Define: i) Flood ii) Design flood.
4 M
4 (b) Discuss in brief the following method of flood control:
i) Reservoir control
ii) Construction of levels
iii) Channel improvement.
9 M
4 (c) Define Flood routing and which are formulas used for storage versus elevation determination and outflow versus elevation determination.
7 M

5 (a) Define Irrigation and what are the benefits and ill effects of irrigation.
6 M
5 (b) Discuss in brief the following types of irrigation:
i) Flow irrigation
ii) Direct irrigation
iii) Storage irrigation
iv) Inundation irrigation.
8 M
5 (c) Write a note on:
i) Sewage irrigation
ii) Well irrigation
iii) Supplemental irrigation.
6 M

6 (a) Describe with the help of sketch various soil moisture zone.
6 M
6 (b) Define: i) Saturation capacity ii) Field capacity iii) Permanent writing iv) Temporary writing.
8 M
6 (c) Discuss in brief: i) Alluvial soil ii) Black soil iii) Red soil
6 M

7 (a) Define Duty and delta and establish a relation between them.
6 M
7 (b) What are the various methods of improving duty of irrigation water?
6 M
7 (c) The base period, duty at the field of different crops and area under each, crop in the command are given below. Find the required reservoir capacity to cater to the needs of the crop.
Crop Base Period (days) Duty @ field ha/cumes Area under the crop (Ha)
Wheat  120 1800 4800
Sugarcane  360 800 5600
Cotton 200 1400 2400
Rice 120 900 3200
8 M

8 (a) How irrigation canals are classified?
6 M
8 (b) Discuss the drawback of Kennedy's theory.
4 M
8 (c) A channel section is to be designed for the following data:
Discharge Q=5 cumec
Slit factor f=1.0
Side slope = 1/2 (H): 1 (V)
Also determine the bed slope of the channel by Lacey's method of channels design.
10 M

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