CE-802-A Engineering Hydrology - Dec 2025 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
   aDescribe the hydrologic cycle with neat sketch and also write the detail note on water budget equation.
   How to answer

   • Definition and components of hydrologic cycle: precipitation, evaporation, transpiration, infiltration, runoff, groundwater flow
   • Explain continuity and circulation between atmosphere, surface and subsurface
   • Water budget equation: P = R + E + delta S with terms defined
   • Neat sketch showing cycle with arrows and storages
2. 7 Marks
   bExplain the procedure for supplementing the missing rainfall data. The maximum one day rainfall indicated that a depth of $280\,mm$ had return period of $50$ years. Determine the probability of a one-day rainfall depth equal to or greater than $280\,mm$ at this city occurring (i) Once in $20$ successive years (ii) two times in $15$ successive years and (iii) at least once in $20$ successive years.
   How to answer

   • Procedure for supplementing missing rainfall data: normal ratio, station average, regression methods
   • Return period T=50 years gives annual exceedance probability p=1/T
   • Use binomial distribution for probability in n successive years
   • Calculate (i) once in 20 years, (ii) twice in 15 years, (iii) at least once in 20 years
3. 7 Marks
   aA $6\,h$ storm produced rainfall intensities of $7$, $18$, $25$, $12$, $10$ and $3\,mm/h$ in successive one hour intervals over a basin of $800\,sq.\,km$. The resulting runoff is observed to be $2640$ hectare-metres. Determine $\Phi$ index for the basin.
   How to answer

   • Compute total precipitation depth from hourly intensities
   • Compute runoff depth = runoff volume / basin area
   • Apply phi-index definition: total infiltration / duration of rainfall excess
   • Trial to exclude non-contributing periods and solve for Phi
4. 7 Marks
   bThe ordinates of a $12$-h unit hydrograph are given. Determine the ordinates of an S-curve hydrograph and using this determine the ordinates of $6$-h unit hydrograph.

   How to answer

   • Explain S-curve construction by lagging 12-h UH by 12 h and cumulative addition
   • Compute S-curve ordinates from given 12-h UH table
   • Derive 6-h UH as difference of two S-curves 6 h apart multiplied by 12/6
   • Tabulate ordinates of S-curve and 6-h UH
5. 7 Marks
   aWrite detail note on any two:

   1. i)Method of superposition
   2. ii)Instantaneous Unit Hydrograph
   3. iii)Synthetic Unit Hydrograph
   How to answer

   • Select any two topics from superposition, IUH, synthetic UH
   • Define concept, assumptions and procedure
   • Give equations/diagram for chosen methods
   • Mention applications and limitations
6. 7 Marks
   bGive details about various types of rain gauges used in India with their merits and demerits. Also discuss in detail the various forms of precipitation also write a short note on convective and orographic precipitation.
   How to answer

   • Classify rain gauges: non-recording vs recording, Symons, tipping bucket, weighing, float type
   • Merits and demerits of each type used in India
   • Forms of precipitation: rain, snow, drizzle, hail, sleet, glaze
   • Short note on convective and orographic precipitation with diagrams
7. 7 Marks
   aThe cumulative depth of infiltration in an experiment on a tube infiltrometer is observed to follow the equation $F=0.165t^{0.65}$ where $F$ is in $cm$ and $t$ is in minutes. Determine the equation for infiltration rate and average infiltration rate.
   How to answer

   • Cumulative infiltration F = 0.165 t^0.65 with F in cm, t in minutes
   • Infiltration rate f = dF/dt by differentiation
   • Average infiltration rate = F/t
   • Substitute constants and express units
8. 7 Marks
   bDistinguish between (i) Infiltration capacity and Infiltration Rate (ii) Actual and potential evaporation (iii) Field capacity and permanent wilting point (iv) Depression storage and interception.
   How to answer

   • Define infiltration capacity vs actual rate, factors controlling each
   • Define actual vs potential evaporation and measurement
   • Define field capacity vs permanent wilting point in soil moisture
   • Define depression storage vs interception with hydrologic role
9. 7 Marks
   aFor a river the estimated flood peaks for two return periods by the use of Gumbel's method are as follows. Estimate the flood magnitude in this river with a return period of $1000$ years.

   How to answer

   • Recall Gumbel equation x_T = mean + K_T * sigma with frequency factor
   • Use two given T values to solve for Gumbel parameters
   • Extrapolate to T=1000 years
   • Compute flood magnitude
10. 7 Marks
    bAnalysis of annual flood series of a river yielded a sample mean of $1000\,m^3/s$ and standard deviation of $5000\,m^3/s$. Estimate the design flood of structure on this river to provide $90\%$ assurance that the structure will not fail in next $50$ years. Use Gumbel's method and assume the sample size to be very large.
    How to answer

    • Given mean=1000 m3/s, std dev=5000 m3/s, large sample
    • Risk concept: 90% assurance of no failure in 50 years gives design return period
    • Compute reduced variate y_T for design T
    • Apply Gumbel formula to get design flood
11. 7 Marks
    aA well of $0.5\,m$ diameter penetrates fully into a confined aquifer of thickness $20\,m$ and hydraulic conductivity $8.2 \times 10^{-4}\,m/s$. What is the maximum yield expected from this well if the draw down in the well is not to exceed $3$. The radius of influence may be taken as $260\,m$.
    How to answer

    • Use Thiem equilibrium formula for confined aquifer Q=2 pi K b s / ln(R/rw)
    • Insert diameter 0.5 m, b=20 m, K=8.2e-4 m/s, s=3 m, R=260 m
    • Compute maximum yield
    • State units in m3/s
12. 7 Marks
    bDevelop an equation relating the steady state discharge from a well in an unconfined aquifer and depths of water table at two known positions from the well. State clearly all the assumption involved in your derivation.
    How to answer

    • State Dupuit assumptions for steady radial flow in unconfined aquifer
    • Apply Darcy's law to cylindrical surface and integrate from well to observation points
    • Derive Q = pi K (h2^2 - h1^2)/ln(r2/r1)
    • List all assumptions clearly
13. 7 Marks
    aA flood of $4000\,m^3/s$ in a certain river has a return period of $40$ years. (i) What is its probability of exceedence? (ii) What is the probability that a flood of $4000\,m^3/s$ or greater magnitude may occur in next $20$ years? (iii) What is the probability of occurrence of a flood of magnitude less than $4000\,m^3/s$?
    How to answer

    • Exceedance probability p = 1/T = 1/40
    • Probability of >=4000 m3/s in next 20 years = 1-(1-p)^20
    • Probability of magnitude less than 4000 = 1-p
    • Compute numerical values
14. 7 Marks
    bDescribe the numerical method of hydrologic reservoir routing.
    How to answer

    • Define hydrologic reservoir routing and continuity equation dS/dt = I - Q
    • Explain storage-discharge relation and time step discretization
    • Steps of numerical method: trial, Modified Puls / Goodrich method
    • Mention computation table and iteration
15. 7 Marks
    aRoute the following flood hydrograph through a river reach for which Mushkingum coefficient $K= 8$ hours and $x=0.25$. The initial outflow discharge from the reach is $8.0\,m^3/s$.

    How to answer

    • Recall Muskingum equation S = K[xI + (1-x)Q] and routing coefficients C0,C1,C2
    • Compute C0,C1,C2 for K=8 h, x=0.25, dt=4 h
    • Route inflow hydrograph step by step starting Q0=8.0 m3/s
    • Tabulate outflow discharges
16. 7 Marks
    bDistinguish between :

    1. i)Hydraulic and hydrologic method of flood routing
    2. ii)Hydrologic storage routing and hydrologic channel routing.
    How to answer

    • Define hydraulic vs hydrologic routing: Saint-Venant vs continuity + storage relation
    • Compare data needs, accuracy, application
    • Define hydrologic storage vs channel routing: level pool vs Muskingum
    • Tabulate differences