CE-802-A Engineering Hydrology - May 2024 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aWhat are the different types of precipitation, and how do they vary in terms of form and intensity?
   How to answer

   • Define precipitation and list types: rain, drizzle, snow, sleet, hail, glaze
   • Describe form: liquid vs solid, drop/crystal size
   • Compare intensity ranges and formation mechanism
   • Summarize variation table
2. 7 Marks
   bHow is precipitation measured? Describe the types of rain gauges commonly used for precipitation measurement.
   How to answer

   • Explain precipitation measurement principle: depth over area
   • Describe non-recording gauges: Symons gauge
   • Describe recording gauges: tipping bucket, weighing, float type
   • Compare uses, advantages and limitations
3. 7 Marks
   aIn a catchment area, the annual rainfall recorded by rain gauges A, B, C, D, E and F are 52, 63, 35, 56, 40 and 59 cm respectively. For a 10% error in estimation of mean rainfall, calculate the optimum number of rain gauges in the area.
   How to answer

   • Compute mean rainfall $\bar{P}$ of 6 gauges
   • Compute standard deviation $\sigma$ and coefficient of variation $C_v$
   • Apply optimum gauge formula $N = (C_v/\epsilon)^2$
   • Round up and comment on additional gauges needed
4. 7 Marks
   bWhat are the different methods used for measuring stream flow? Discuss their principles and applicability.
   How to answer

   • List methods: velocity-area, dilution, weir/flume, slope-area, ultrasonic, ADCP
   • Explain principle of each: $Q=A\times V$, continuity, Manning
   • Discuss applicability: stream size, flow regime, accuracy
   • Summarize selection criteria
5. 7 Marks
   aDescribe various methods of estimating evapotranspiration from water bodies.
   How to answer

   • Define evapotranspiration from water bodies / evaporation
   • Describe water budget, energy budget, mass transfer methods
   • Describe empirical formulae: Meyer, Penman, pan evaporation
   • Compare data needs and applicability
6. 7 Marks
   bDiscuss various infiltration equations. Explain how the constants $f_c$, $f_o$ and k in Horton's equation can be obtained from experimental data?
   How to answer

   • List infiltration models: Horton, Philip, Green-Ampt, Kostiakov
   • Write Horton's equation $f_t = f_c+(f_o-f_c)e^{-kt}$
   • Explain graphical / curve fitting to get $f_c, f_o, k$ from data
   • Mention significance of constants
7. 7 Marks
   aThe rate of infiltration into a soil is given by the equation $f(t) = k \cdot t^2$, where $f(t)$ is the infiltration rate in mm/hour and $t$ is the time in hours. If $k = 0.2$ mm/hour, calculate the infiltration rate after 4 hours.
   How to answer

   • State given equation $f(t)=k\cdot t^2$ and parameters
   • Substitute $k=0.2$ mm/hour and $t=4$ hours
   • Compute $f(4)$ value with units mm/hour
   • Comment on result
8. 7 Marks
   bA soil has a maximum infiltration capacity $(f_c)$ of 10 mm/hour and a constant rate of infiltration $(f)$ of 2 mm/hour. Write the infiltration equation for this soil and determine the time it takes for the infiltration rate to reach 8 mm/hour.
   How to answer

   • Write Horton's form $f = f_c+(f_o-f_c)e^{-kt}$ or given linear form
   • Identify $f_c=10$ mm/hour and $f=2$ mm/hour constants
   • Set $f=8$ mm/hour and solve for $t$
   • Obtain time required
9. 7 Marks
   aA researcher is studying the impact of soil texture on infiltration rates. In a sandy soil, the infiltration rate is found to be 0.5 mm/hour, while in a clayey soil, it's 0.2 mm/hour. Calculate the difference in infiltration rates between these two soil types.
   How to answer

   • Note sandy soil rate 0.5 mm/hour and clayey soil rate 0.2 mm/hour
   • Compute difference $0.5-0.2 = 0.3$ mm/hour
   • Explain texture effect: porosity and permeability
   • State conclusion
10. 7 Marks
    bCalculate the synthetic unit hydrograph for a watershed given the following parameters: time to peak $(T_p) = 2.5$ hours, time of concentration $(T_c) = 5$ hours, and basin lag time $(T_l) = 0.2 \times T_c$
    How to answer

    • Compute basin lag $T_l = 0.2 \times T_c$
    • Use Snyder's synthetic UH relations for $T_p$, $q_p$, base width
    • Compute peak discharge and time ordinates
    • Sketch synthetic triangular/curvilinear UH shape
11. 7 Marks
    aDefine a hydrograph and explain its components. How does a hydrograph represent the response of a watershed to a rainfall event?
    How to answer

    • Define hydrograph: discharge vs time at outlet
    • Explain components: rising limb, peak, recession, baseflow
    • Relate rainfall excess to direct runoff response
    • Explain watershed characteristics effect
12. 7 Marks
    bThe ordinates of a 4 h UH of a basin of area 300 $km^2$ measured at 1h 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. Obtain the ordinates of a 3h UH for the basin using the S-curve techniques.
    How to answer

    • Tabulate given 4-h UH ordinates at 1-h interval and check volume
    • Construct S-curve by lagging 4-h UH and derive equilibrium flow
    • Lag S-curve by 3-h, find difference and multiply by 4/3
    • List resulting 3-h UH ordinates
13. 7 Marks
    aDefine the concept of an instantaneous unit hydrograph (IUH). How does it differ from a Conventional unit hydrograph?
    How to answer

    • Define IUH: UH for infinitesimal duration, impulse response
    • Explain derivation: limit $D \to 0$, Nash / conceptual models
    • Contrast with finite-D conventional UH in shape and use
    • Mention application to derive any-D UH by convolution
14. 7 Marks
    bCompare and contrast the characteristics and applications of reservoir routing and channel routing methods in flood routing analysis.
    How to answer

    • Define reservoir routing: storage effect, level pool; channel routing: translation + attenuation
    • Compare governing equations: continuity + storage vs Muskingum / Saint-Venant
    • Contrast applications: dam outflow vs river reach flood propagation
    • Summarize differences in table
15. 7 Marks
    aDiscuss the causes of reservoir sedimentation and the factors influencing the rate of sediment deposition.
    How to answer

    • Define reservoir sedimentation and sediment yield
    • List causes: erosion, land use, runoff, stream load
    • Explain factors: trap efficiency, capacity-inflow ratio, particle size
    • Mention effects on storage and life
16. 7 Marks
    bExplain the various methods used for controlling reservoir sedimentation, including sediment flushing, dredging and watershed management practices.
    How to answer

    • List control measures: watershed management, check dams, flushing
    • Explain sediment flushing / sluicing operation
    • Explain dredging types and limitations
    • Discuss watershed practices: afforestation, contour bunding