JUP – 090

*JUP090*

I Semester M.E. (Civil) (Environmental Engineering) Degree Examination, February 2014 2K8 EN 105 : HYDROLOGY AND HYDRAULICS IN ENVIRONMENTAL ENGINEERING Time : 3 Hours

Max. Marks : 100

Note : 1) Answer any five full questions. 2) Missing data can be suitably assumed. 3) Be brief and relevant.

1. a) Discuss the important objectives of water supply and waste water disposal. b) Mention the different methods employed to forecast the population also highlighting the suitability of each method. c) Estimate the population of a city for the year 2021 and 2031 from the following data. Census Year

: 1961

1971

1981

1991

2001

Population in Thousands : 143

159

163

199

227

Adopt any two methods. 2. a) What is a hydrological cycle ? How does it keep a balance between the water of the earth and the moisture in the atmosphere ? What is the importance of the hydrological cycle in hydrologic analysis ? b) Define the terms : Aquifer, unconfined aquifer, confined aquifer, porosity, specific yield. c) Explain infiltration galleries and infiltration wells with neat sketches. 3. a) Discuss briefly the common stresses developed in pipe lines used for converging water. What arrangements are made in their design and construction to resist them ?

P.T.O.

JUP – 090

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*JUP090*

b) Draw a typical sketch of a sewage pumping station for a town having a population of 60,000, supplied with a per capita water supply of 135 litres per day. The sewage from this town enters the pumping station through a descending sewer at R-L. 105.0 m and leaves thru’ a high levelled sewer at R-L 115 M. The town has been provided with a separate sewerage system and there are no chances of storm water getting infiltrated into sewers. Calculate the size of the rising main size of the sump well and BHP of the pump motor required. Assume the length of the rising main as 100 m. Assume missing data wherever needed. 4. a) A low lying residential colony is having a population of 5500 persons. The colony gets a per capita supply of water at the rate of 135 lpcd. A separate sewerage system for the colony is installed. It is further required to lift the entire sewage of the colony by installing an air ejector. Assuming the velocity in the main sewer as 0.9 m/sec and velocity of compressed air as 5 m/sec. Design the ejector. b) Discuss the four principle systems adopted in plumbing of drainage work of a building. 5. a) Discuss the factors that are considered while estimating the quantity of dry weather flow. Also indicate the reasons for the variation in the rate of sewage and its effects on the design of sewers. b) Estimate the ratio of DWF and WWF of a city with following particulars. Area to be served = 20,000 hectares Rate of water supply = 140 lpcd Population = 12 × 105 Intensity of rainfall = 12 mm per hour Average impermeability factor = 0.50 Assume 80% of the water supplied comes back on sewage. Comment on the result. c) Calculate the discharge, velocity and Chezy’s co-efficient for a stone wave sewer running full-with diameter of sewer is 15 cm laid at a gradient of 1 in 50. Assume N = 0.013 in Mannings formula.

*JUP090*

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JUP – 090

6. a) Discuss the various factors that affects the runoff from a basin. Also explain the methods of estimating runoff from a catchment. b) An intense rain assumed to be falling at a uniform rate of 5 cm/hr for a period of 80 minutes, on a drainage basin having an area equal to 610 hectares. The average infiltration capacity during the entire period has been worked out to be 1.4 cm/hr. Determine the maximum run off rate, if the peak percentage based on 12 minutes interval from the distribution graph for this basin is 21%. 7. a) What are the objectives of water distribution system ? b) Explain briefly the different methods of analysis of distribution network. c) Find the equivalent pipe AD for the simple network ABCD as shown in fig. 1

Fig. 1 8. Write short notes on any four : 1) Design period 2) Surge Tanks 3) Laminar and turbulent flows 4) Sewer transitions 5) Yield tests 6) Ground water recharge. ————————