# HYDROLOGY 6th AM11 CE2021

Question Paper Code : 11197 421
B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2011
Sixth Semester
Civil Engineering
CE 2021 - HYDROLOGY
(Regulation 2008)

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PART A — (10 × 2 = 20 marks)

1. What are the various forms of precipitation?
2. Define Probable Maximum Precipitation.
3. How do you control reservoir evaporation?
4. How do you measure infiltration?
6. What are the limitations of unit hydrograph theory?
5. Define time of concentration.
7. Define Recurrence interval of flood.
8. A flood has a return period of 23 years. What is the Probability exceedance of the flood?
9. Define aquifer.
10. State the limitations of Darcys law.

PART B — (5 × 16 = 80 marks)

11. (a) (i) Explain Hydrologic Cycle with neat sketch. (10)
(ii) What are the various types of precipitation? (6)
Or
(b) (i) How do you measure rainfall? (10)
(ii) Analysis of data on maximum one-day rainfall depth at Chennai indicated that a depth of 280 mm had a return period of 50 years Determine the probability of a one-day rainfall depth equal to or greater than 280 mm at Chennai occurring (1) once in 20 successive years (2) twice in 15 successive Years (6)

12. (a) (i) What are the factors affecting evaporation losses? (6)
(ii) A 6 hr storm produced rainfall intensities of 7, 18, 25, 12, 10 and 3 mm/hr in successive one hour intervals a basin of 800 sq.km. The resulting runoff is observed to be 2640 ha.m. Determine Ø - index for the basin. (10)
Or
(b) How do you measure evaporation Using Pan and Water Budget (16)

13. (a) (i) What are the factors affecting flood hydrograph? Explain. (8)
(ii) In a 4 hr. storm with 50 mm of excess rainfall from a basin, the flows in the stream were as follows :
Time (hrs) : 0 2 4 6 8 12 16 20 Flow (m^3/s) : 0 1.22 4.05 6.75 5.67 3.375 1.35 0
(1) Determine the ordinates of unit hydrograph least once in 20 successive years. (6)
(2) Estimate the peak flow and the time of its occurrence in a flood created by a 8 hr storm, which results in 2.5 cm of effective rainfall during the first 4 hours and 3.75 cm of effective rainfall during the second 4 hours. Assume the base flow as negligible. (2)
Or
(b) (i) State the assumptions in unit hydrograph theory. (6)
(ii) The ordinates of a 4 hr unit hydrograph of a basin of area 300 sq.km. measured at 1 hr intervals are 6, 36. 66.91, 106, 93.79, 68, 58.49, 41, 34, 27, 23, 17, 13, 9,6,3 and 1.5 m^3/s respectively. Determine the ordinates of a 3 hr Unit hydrograph for the basin. (10)

14. (a) (i) How do you determine the magnitude of flood of specific return period using Gumbels method? (6)
(ii) The 50 year and 100 year flood have been estimated to be 660 m^3/s and 740 m^3/s from the available data of annual flood peaks of a small stream for a period of 35 years using Gumbels method. Estimate the 200 year flood in the stream. (10)
Or
(b) (i) Explain briefly about various Flood control measures. (6)
(ii)Reach and derive the outflow hydrographic. The values of K and X for the reach may be taken as 12 hr and 0.278 respectively, time is in hours and flow is in cumecs. (10)
Time 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56
Flow 42 68 116 164 194 200 192 170 150 128 106 88 74 62 54

15. (a) (i) What are the various types of aquifers? Explain. (8)
(ii) How do you determine the Specific Yield using Recuperation Test? (8)
Or
(b) (i) State the assumptions and limitations of Dupuits Theory. (6)
(ii) Route the flood hydrograph given below through a channel well is 40 m before the pumping is started. When pumping is being done at the rate of 3.33 × 10^–2 cumecs, the drawdown in a well 10 m away is 4 m and in another well 20 m away is 2 m. Determine :
(1) Drawdown in the well
(2) Co-efficient of permeability
(3) Drawdown in the well
(4) The maximum rate at which water can be pumped from the well. (10)