Engineering Hydrology- Model question paper for B.E/B.Tech Civil engineering

1(a) Describe the hydrologic cycle. Explain briefly the man’s interference in various parts of this cycle. (06 Marks)

(b) Explain the different methods of determining the average rainfall over a catchment due to a storm. Discuss the relative merits and demerits of the various methods. (06 Marks)

(c) What is meant by Probable Maximum Precipitation (PMP) over a basin? Explain how PMP is estimated? (04 Marks)

(d) 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 (a) once in 20 successive years, (b) two times in 15 successive years, and (c) at least once in 20 successive years. (04 Marks)

2(a) Explain a procedure for fitting Horton’s infiltration equation for experimental data from a given plot. (06 Marks)

(b) List the various data needed to use Penman’s equation for estimating the potential evapotranspiration from a given area. (04 Marks)

(c) Discuss the importance of evaporation control of reservoirs and possible methods of achieving the same. (06 Marks)

(d) In a 140-min storm, the following rates of rainfall were observed in successive 20-min intervals: 6.0, 6.0, 18.0, 13.0, 2.0, 2.0 and 12.0 mm/h. Assuming the φ-index value as 3.0 mm/h and an initial loss of 0.8 mm, determine the total rainfall, net runoff and W-index for the storm. (04 Marks)

3(a) Discuss the advantages and disadvantages of the following relative to the flow measurement by using current meters:

(i) Electromagnetic method        (ii) Ultrasound method. (06 Marks)

(b) Explain the procedure for obtaining the stage-discharge relationship of a stream by using the stage-discharge data from a site with permanent control. (06 Marks)

(c) Describe briefly the moving boat method of stream flow measurement. (04 Marks)

(d) It is proposed to adopt the dilution method of stream gauging for a river whose hydraulic properties at average flow are as follows:

Width = 45 m, Depth = 2 m, Discharge = 85 m³/s, Chezy coefficient = 20 to 30. Determine the safe mixing length that has to be adopted for this stream. (04 Marks)

4(a) What is a hydrological drought? What are its components and their possible effects? (06 Marks)

(b) Distinguish between yield and surface water resources potential of a basin having substantial water resources development for meeting irrigation, domestic and industrial needs within the basin. (06 Marks)

(c) Describe briefly the SCS-CN method of estimation yield of a catchment through use of daily rainfall record. (04 Marks)

(d) A reservoir is located in a region where the normal annual precipitation is 160 cm and the normal annual US class A pan evaporation is 200 cm. The average area of reservoir water surface is 75 km². If under conditions of 35% of the rainfall on the land occupied by the reservoir runoff into the stream, estimate the net annual increase or decrease in the stream flow as result of the reservoir. Assume evaporation pan coefficient = 0.70. (04 Marks)

5(a) Why is base flow separated from the flood hydrograph in the process of developing a unit hydrograph? (04 Marks)

(b) Describe the S-curve method of developing a 6-h UH by using 12-h UH of the catchment. (04 Marks)

(c) The 6-hour unit hydrograph of a catchment is triangular in shape with a base width of 64 hours and a peak ordinate of 30 m³/s. Calculate the equilibrium discharge of the S₆ – curve of the basin. (06 Marks)

(d) The 6-hour unit hydrograph of a basin is triangular in shape with a peak of 100 m³/s occurring at 24-h from the start. The base is 72-h.

(i) What is the area of the catchment represented by this unit hydrograph?

(ii) Calculate the flood hydrograph due to a storm of rainfall excess of 2.0 cm during the first 6 hours and 4.0 cm during the second 6 hours interval. The base flow can be assumed to be 25 m³/s constant throughout. (06 Marks)

6(a) Annual flood series having N consecutive entries are available for a catchment. Describe a procedure to verify whether the data follow Gumbel’s distribution. (06 Marks)

(b) Describe a numerical method of hydrologic reservoir routing. (04 Marks)

(c) Describe the Muskingum method of flood routing an inflow hydrograph through a channel reach. Assume the values of coefficients K and x for the reach are known. (06 Marks)

(d) A rectangular parking lot is 150m wide and 300m long. The time of overland flow across the pavement to the longitudinal gutter along the center is 20 minutes and the estimated total tome of concentration to the downstream end of the gutter is 25 minutes. The coefficient of runoff is 0.92. If a rainfall of intensity 6 cm/h falls on the lot for 10 minutes and stops abruptly, determine the peak rate flow. (04 Marks)

7(a) Explain the behaviour of water level in wells in confined aquifers due to changes in the atmospheric pressure. (04 Marks)

(b) Describe a procedure by using Jacob’s method to calculate the aquifer parameters of a confine aquifer by using the well pumping test data. (06 Marks)

(c) What are Dupit’s assumptions? (04 Marks)

(d) A 30-cm well completely penetrates an artesian aquifer. The length of the strainer is 25m. Determine the discharge from the well when the drawdown at the pumping well is 4.0m. The coefficient of permeability of the aquifer is 345 m/day. Assume the radius of the well as 350m. (06 Marks)

8(a) What is meant by Trap Efficiency of a reservoir? What factors influence its value? (04 Marks)

(b) Explain the area-increment method of determining the sedimental distribution in a reservoir. (06 Marks)

(c) Distinguish between USLE and MUSLE? (06 Marks)

(d) A reservoir sediment is estimated through use of Koezler equation to have average unit weight of 1100 kg/m³ at the end of 35 years and 1120 kg/m³ at the end of 50 years. Estimate the average unit weight at the end of first year of deposit and at the end of 100 years. (04 Marks)