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VTU Civil Engineering (Semester 5)
Hydrology & Irrigation Engineering
June 2015
Total marks: --
Total time: --
INSTRUCTIONS
(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) Define hydrology and explain briefly the practical applications of Hydrology.
8 M
1 (b) Explain how the Double mass curve method is used to test the consistency of rainfall record.
6 M
1 (c) The average annual rainfall of 8 rain gauge station in basin are 1000, 950, 900, 850, 800, 700, 600, 400mm. If the permissible error is 6% determine the optimum number of rain gauges required in the basin.
6 M

2 (a) Define Evaporation (E) and Evapo-transpiration (ET) and list out the factors affecting the evaporation.
6 M
2 (b) Mention the different methods of measurement of rate of infiltration and describe anyone of them.
8 M
2 (c) For a storm of 2 hr duration the rainfall rates are given below:
If ϕ-index is 3 cm/hr, estimate the surface runoff. Also determine W-Index.
 Time period (minutes) 20 20 20 20 20 20 Rainfall rate (cm/hr) 2.5 2.5 10 7.5 5.1 1.25
6 M

3 (a) What is Unit hydrograph? State the assumptions and limitations of Unit Hydrograph Theory. (Any 3 each).
8 M
3 (b) Explain how base flow is separated from a simple storage hydrograph, with a neat sketch (any two methods).
6 M
3 (c) The ordinates of 4hr unit hydrograph are given below. Determine the ordinates of 12 hr unit hydrograph.
 Time (hr) 0 4 8 12 16 20 24 28 32 36 40 44 48 Ordinates of unit hydrograph (4hr) cumecs 0 5 110 220 150 115 90 70 60 50 30 20 0
6 M

4 (a) Define the terms Flood and Flood routing.
4 M
4 (b) What is the importance of Design Flood? List out the factors affecting flood.
8 M
4 (c) An Urban catchment has an area of 1km2. The slope of the catchment is 0.005 and the maximum length of travel of water is 500m. The maximum depth of rainfall with a 20 years return period is as given below:
Estimate the required peak flow rates by using runoff co-efficient as 0.40.
 Duration (tc) (minutes) 10 15 20 Depth of rainfall (cm) 4 5 6
8 M

5 (a) Define the term Irrigation and Explain the necessity of Irrigation in India.
6 M
5 (b) Explain the Flow Irrigation System with the aid of necessary sketches.
8 M
5 (c) Write a note on Environmental impacts of Irrigation.
6 M

6 (a) Explain the essential soil conditions for good plant growth.
6 M
6 (b) Give a brief classification of Indian soils.
6 M
6 (c) After how many days you will supply water to soil in order to ensure sufficient irrigation of the given crop, if field capacity of the soil is 35%, permanent wilting point is 18%, density of soil is 1.50 gm/cc, effective depth of root zone is 70 cm and daily consumptive use of water for the given crop is 17mm. Assume that readily available moisture is 75% of the available moisture.
8 M

7 (a) Define Duty and Delta and given the relationship between them.
4 M
7 (b) Explain the terms: i) Base period ii) Crop period iii) Crop season iv) Irrigation requirement.
8 M
7 (c) Two canal system A and B have the cultural command area of 30000 ha and 15000 ha and discharge 20m3/S and 10m3/S respectively. The Intensity of Rabi crop and Base period for canal A are 85% and 120 days. For canal B intensity of Rabi crop and the Base period are 50% and 120 days. Which system is more efficinet?
8 M

8 (a) Describe briefly the various considerations made in the alignment of an irrigation canal.
6 M
8 (b) Explain briefly the classification of canal based on alignment.
6 M
8 (c) Design an Irrigation channel by Kennedy's theory to carry a discharge of 5 cumecs. Take m=1.0, N=0.0225 and B/D=3.24.
8 M

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