GATE Environmental Engineering Water Resources and Environmental Hydraulics Syllabus

Water Resources and Environmental Hydraulics syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Water Resources and Environmental Hydraulics in GATE Environmental Engineering, not a summary of it.

1. 1

   Global Water Resources

   4 topics

   • Structure, properties and distribution of water
   • Water quality
   • Threats to water resources
   • Water conservation
2. 2

   Surface Water Resources

   9 topics

   • Hydrological cycle and water balance - precipitation, infiltration, evapotranspiration, runoff
   • Flow hydrographs
   • Unit hydrographs
   • Stage-discharge relationship
   • Reservoir capacity
   • Reservoir and channel routing
   • Surface run-off models
   • Surface water management
   • Rain water harvesting and storage
3. 3

   Groundwater Resources

   5 topics

   • Geologic formations as aquifers
   • Vadose and saturated zones
   • Confined and unconfined aquifers and their parameters - porosity, permeability, transmissivity and storage coefficient
   • Darcy’s law and applications
   • Steady state well hydraulics
4. 4

   Environmental Hydraulics

   15 topics

   • Concepts of mechanics
   • Properties of fluids
   • Pressure measurement
   • Hydrostatic force on surfaces
   • Buoyancy and flotation
   • Laminar and turbulent flow
   • Flow through pipes
   • Pipe networks
   • Boundary layer theory
   • Forces on immersed bodies
   • Flow measurement in channels and pipes
   • Kinematics of flow
   • Continuity, momentum and energy equations
   • Channel hydraulics - specific energy, critical flow, hydraulic jump, rapid and gradually varied flow
   • Design of lined and unlined channels

Water Resources and Environmental Hydraulics flashcards for GATE Environmental Engineering

20 of 50 cards from the Water Resources and Environmental Hydraulics deck — real questions with worked answers.

1. What fraction of Earth's total water is freshwater, and what fraction of that freshwater is readily accessible as surface water (lakes, rivers)?

   Only about $2.5\%$ of Earth's water is freshwater; of that, roughly $68.7\%$ is locked in ice/glaciers, about $30.1\%$ is groundwater, and only about $0.3\%$ is surface water in lakes and rivers.

2. Why does the water molecule's structure give water its high boiling point, high specific heat, and solvent power?

   The bent $\ce{H2O}$ molecule is polar (oxygen partially negative, hydrogens partially positive), enabling extensive hydrogen bonding. This produces a high boiling point, high specific heat ($\approx 4.18\ \mathrm{kJ\,kg^{-1}\,K^{-1}}$), high latent heat, and makes water a strong universal solvent.

3. At what temperature does liquid water reach its maximum density, and why is this anomaly important?

   Water is densest at about $4\ ^\circ\mathrm{C}$ ($\approx 1000\ \mathrm{kg/m^{3}}$). Ice is less dense than liquid water, so ice floats and lakes freeze top-down, insulating aquatic life below.

4. List the principal physical, chemical, and biological water-quality parameters.

   Physical: temperature, turbidity, color, taste, odor, total solids (TDS/TSS). Chemical: pH, DO, BOD, COD, hardness, alkalinity, nutrients (N, P), heavy metals. Biological: total/fecal coliforms, pathogens, algae.

5. Define BOD and COD and state how they differ.

   BOD (Biochemical Oxygen Demand) is the oxygen consumed by microorganisms while biologically oxidizing organic matter (standard test $\mathrm{BOD_5}$ at $20\ ^\circ\mathrm{C}$ for 5 days). COD (Chemical Oxygen Demand) is oxygen needed to chemically oxidize organic matter using a strong oxidant. COD $\geq$ BOD because it also oxidizes non-biodegradable matter.

6. Write the first-order BOD rate equation and the formula for BOD exerted after time $t$.

   $$\frac{dL}{dt} = -k_D L \quad\Rightarrow\quad L_t = L_0 e^{-k_D t}$$ The BOD exerted is $y_t = L_0\left(1 - e^{-k_D t}\right)$, where $L_0$ is ultimate BOD and $k_D$ is the deoxygenation rate constant.

7. What is water hardness, how is it expressed, and what are typical hardness classes?

   Hardness is caused mainly by $\ce{Ca^{2+}}$ and $\ce{Mg^{2+}}$, expressed as $\mathrm{mg/L}$ of equivalent $\ce{CaCO3}$. Classes: soft $<75$, moderately hard $75\text{–}150$, hard $150\text{–}300$, very hard $>300\ \mathrm{mg/L}$ as $\ce{CaCO3}$.

8. What is the difference between carbonate (temporary) and non-carbonate (permanent) hardness?

   Carbonate hardness is due to bicarbonates/carbonates of $\ce{Ca}$ and $\ce{Mg}$ and is removable by boiling (temporary). Non-carbonate hardness is due to sulfates, chlorides, and nitrates of $\ce{Ca}$ and $\ce{Mg}$, not removable by boiling (permanent).

9. Name the major threats to water resources.

   Point and non-point source pollution, eutrophication from nutrient loading, over-abstraction/depletion of groundwater, saltwater intrusion, sedimentation, industrial and agricultural contamination, climate change altering precipitation, and loss of catchment/wetland areas.

10. What is eutrophication and which limiting nutrient is usually responsible?

    Eutrophication is excessive nutrient enrichment of a water body causing algal blooms, oxygen depletion, and ecosystem degradation. Phosphorus is typically the limiting nutrient in freshwater systems.

11. List effective water conservation measures in agriculture, industry, and households.

    Agriculture: drip/sprinkler irrigation, crop scheduling, lined canals. Industry: recycling and reuse, closed-loop cooling. Domestic: low-flow fixtures, leak repair, dual-flush toilets, greywater reuse, and rainwater harvesting.

12. State the components of the hydrological cycle and the general water balance equation for a catchment.

    Components: precipitation, interception, infiltration, evaporation, transpiration, surface runoff, groundwater flow, and storage. Water balance: $$P = R + E + T + \Delta S$$ where $P$=precipitation, $R$=runoff, $E$=evaporation, $T$=transpiration, $\Delta S$=change in storage.

13. Name the common methods for computing average rainfall over a catchment.

    Arithmetic mean method, Thiessen polygon (area-weighted) method, and the isohyetal method. The isohyetal method is generally the most accurate for non-uniform terrain.

14. Write Horton's infiltration capacity equation and define its terms.

    $$f_p = f_c + (f_0 - f_c)e^{-kt}$$ where $f_p$=infiltration capacity at time $t$, $f_0$=initial infiltration capacity, $f_c$=final (steady) capacity, and $k$=decay constant ($\mathrm{h^{-1}}$).

15. Define the $\phi$-index and the $W$-index in infiltration analysis.

    The $\phi$-index is the constant rainfall intensity (loss rate) above which rainfall volume equals direct runoff volume. The $W$-index is the average infiltration rate during the period when rainfall intensity exceeds infiltration capacity; $W \leq \phi$ because $W$ excludes interception and depression storage.

16. Distinguish between potential evapotranspiration (PET) and actual evapotranspiration (AET).

    PET is the evapotranspiration that would occur given an unlimited water supply (energy-limited). AET is the actual evapotranspiration constrained by available soil moisture; $\mathrm{AET} \leq \mathrm{PET}$, with equality when water is abundant.

17. Write the Penman energy-balance concept for estimating evaporation.

    Penman's method combines an energy-balance term and an aerodynamic (mass-transfer) term: $$E = \frac{\Delta H_n + \gamma E_a}{\Delta + \gamma}$$ where $\Delta$=slope of saturation vapor-pressure curve, $\gamma$=psychrometric constant, $H_n$=net radiation, and $E_a$=aerodynamic term.

18. What are the four components of a single-peaked flood hydrograph?

    The rising limb (concentration curve), the crest/peak, the recession (falling) limb, and the base flow. The recession limb's shape depends mainly on basin storage characteristics, not on rainfall.

19. What is base flow separation and name a common technique?

    Base flow separation isolates direct surface runoff from groundwater contribution in a hydrograph. The straight-line method, the fixed-base method, and the variable-slope method are common; the result yields the direct runoff hydrograph (DRH).

20. Define a unit hydrograph and state its key assumptions.

    A unit hydrograph is the direct runoff hydrograph resulting from $1\ \mathrm{cm}$ (or $1$ unit) of effective rainfall uniformly distributed over the catchment in a specified duration. Assumptions: linearity (proportionality), time invariance, and superposition (Sherman's principles).

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