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Created: 2026/10/20 14:54 Updated: 2026/10/20 16:05 share_link: https://notesx.azraftaohid.me/unvlmpe8 share_updated: 2026-10-22T08:09:05+06:00

1. Structural Note on Section A vs Section B
2. 1. Master Ranked Frequency Table
3. 2. Mathematical & Numerical Problem Archetypes
4. Quick Reference Summary
5. Core Formulas & Solution Steps
6. 3. Questions Grouped by Lecture Material
7. Section A: River Engineering & River Mechanics (12 Lectures)
   1. SA Lecture 1: Rivers, Alluvial Rivers & Planform Classification
   2. SA Lecture 2: Channel Patterns, Hydraulic Geometry, Bankfull & River Slope
   3. SA Lecture 3: Derived Hydraulic Relations, Meandering Theories & Helical Flow
   4. SA Lecture 4: Channel Stability, Planform Stability Ratios & Sediment Load Modes
   5. SA Lecture 5: Forces in a River, Stream Power, Hjulström & Shields Diagram
   6. SA Lecture 6: Regimes of Flow, Bedforms, Roughness & Fall Velocity
   7. SA Lecture 7: Sediment Transport Rates, Rouse Profile, Dune Bed Load & MPM Equation
   8. SA Lecture 8: Dynamic Adjustment of Rivers — Lane's Relationship, Aggradation & Degradation
   9. SA Lecture 9: River Scour Fundamentals (General, Contraction, Pier & Abutment Scour)
   10. SA Lecture 10: Advanced Scour — Complex Piers, Lacey–Inglis Method & Countermeasures
   11. SA Lecture 11: River Training & Bank Protection Works
   12. SA Lecture 12: Inland Navigation, Cut-Offs & River Dredging
8. Section B: Flood Management (11 Lectures)
   1. SB Lecture 1: Overview of Floods, Types & Causes of Floods in Bangladesh
   2. SB Lecture 2: Flood Process in Urban and Rural Areas
   3. SB Lecture 3: Flood Management Measures, Dams & Hydraulic Structures
   4. SB Lecture 4: Diversion Channels, Floodways & Floodwalls
   5. SB Lecture 5: Improvement of Channel Capacity by Dredging
   6. SB Lecture 6: Land & Watershed Management for Flood Mitigation
   7. SB Lecture 7: Flood Proofing Strategies
   8. SB Lecture 8: Floodplain Zoning & Flood Mapping
   9. SB Lecture 9: Flood Hazard Mapping, Risk Analysis & Frequency Analysis
   10. SB Lecture 10: Flood Forecasting and Warning System
   11. SB Lecture 11: Flood Damage Assessment & Economic Evaluation
9. 4. Near-Verbatim Recurring Questions

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EWCE 461: River Engineering & Flood Management — Past Exam Analysis

An exhaustive, page-verified analysis of all 6 past term-final question papers and 23 official lecture slide decks (SA Lectures 1–12 and SB Lectures 1–11):

1. Question Paper - EWCE 461, 2019.pdf (Spring Final: June 2019)
2. Question Paper - EWCE 461, 2021.pdf (Spring Final: Feb 2021)
3. Question Paper - EWCE 461, 2022.pdf (Spring Final: July–Aug 2021)
4. Question Paper - EWCE 461, 2023.pdf (Spring Final: July–Sept 2023)
5. Question Paper - EWCE 461, 2024.pdf (Spring Final: Oct–Nov 2024)
6. Question Paper - EWCE 461, 2025.pdf (Spring Final: Oct–Nov 2025)

Structural Note on Section A vs Section B

• Course Credit Split: EWCE 461 is 3.0 credits total — Section A (River Engineering) is 2.0 credits (12 lectures) and Section B (Flood Management) is 1.0 credit (11 lectures).
• Exam Paper Split: Both sections carry 90 marks each (180 marks total; Q1 in Sec A and Q5 in Sec B are compulsory). Because Section A covers two-thirds of the syllabus, one question inside Section B of the exam paper (typically Q8, and Q6 in 2022) is set from Section A lecture material (Scour, River Training, Navigation, Dredging, and Lane's Relation).

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1. Master Ranked Frequency Table

Topics are ranked from highest appearance frequency (6/6 exams) down to single-exam appearances (1/6). All page numbers refer to 1-indexed PDF slide pages.

Rank	Question / Core Topic	Frequency	Reference	Years & Specific Questions
1	River / Channel Patterns & Controlling Factors • Alluvial river definition & pattern classification (straight, meandering, braided, anastomosing) by sinuosity & multichanneledness • How slope, sediment load/size, bank silt-clay cohesiveness, and $W/D$ ratio control pattern	6 / 6	SA: Lec 1 (p. 17–18, 23–26) SA: Lec 2 (p. 3–11, 13–15) SA: Lec 3 (p. 5–8)	2019 (Q1a, Q2a), 2021 (Q1a), 2022 (Q1a), 2023 (Q1a), 2024 (Q1c), 2025 (Q1a, Q1b, Q2a)
2	Sediment Load Classification & Transport Modes • Classification by physical nature (particulate vs dissolved), bed presence (bed-material vs wash load), and travel mode (bed vs suspended load) • Capacity-dependent bed load vs supply-dependent wash/suspended load • Why bed & suspended loads are interchangeable; why wash load never settles; why dissolved load is excluded	6 / 6	SA: Lec 4 (p. 9–21) SA: Lec 5 (p. 15–17) SA: Lec 7 (p. 2, 13)	2019 (Q2b), 2021 (Q1c), 2022 (Q2c), 2023 (Q2b, Q2c, Q2d, Q3c, Q3d), 2024 (Q3a, Q3b), 2025 (Q1d)
3	Dredging Operations, Impacts & Sustainability • Dredging purposes & 4 phases (pretreatment, extraction, transport, disposal) • Mechanical vs hydraulic dredging; capital vs maintenance dredging • Morphological/hydraulic response (nickpoint headcutting, pit trapping) & why dredging for navigation is not sustainable	6 / 6	SA: Lec 12 (p. 24, 26–33, 37–46) SB: Lec 5 (p. 7–26)	2019 (Q7a), 2021 (Q7c), 2022 (Q4c, Q4d, Q7d), 2023 (Q8f), 2024 (Q5c, Q7a, Q8b), 2025 (Q4c, Q8b)
4	Bridge Pier & Abutment Scour Mechanisms and Factors • General scour (degradation) vs localized scour; horseshoe vs wake vortices • Factors affecting pier scour (velocity ratio $V/V_c$, flow depth, wide vs narrow pier width, grain size, angle of attack, shape) • Why pier scour > abutment scour; clear-water vs live-bed scour	5 / 6	SA: Lec 9 (p. 1–4, 8–36) SA: Lec 10 (p. 1–5)	2019 (Q3d, Q4a, Q4c, Q4e), 2021 (Q2a, Q3a), 2022 (Q6a), 2023 (Q4b), 2024 (Q1e), 2025 (Q1f, Q4a, Q8c)
5	Spurs / Groynes & Active vs Passive River Training • Active (transverse) vs passive (longitudinal) structures • Spur orientation (attracting, deflecting, repelling) & permeability (permeable vs impermeable) • Slack flow zone, new bankline development, groyne length/spacing design, and bandals	5 / 6	SA: Lec 11 (p. 1, 3–14, 43–46)	2019 (Q4d, Q6c), 2021 (Q3c), 2022 (Q6d, Q8c), 2023 (Q8a), 2024 (Q1f), 2025 (Q4c, Q8a, Q8c)
6	Rouse Number, Fall/Shear Velocity & Suspended Profile • Settling/fall velocity (and particle sphericity effect) vs shear velocity ($u_{*}$) • Rouse number ($R_n=\omega /\kappa u_{*}$) suspension thresholds • Logarithmic vertical profile of concentration & grain size ($d_{10},d_{50},d_{90}$); complexity of suspended load estimation	5 / 6	SA: Lec 4 (p. 17–19, 22) SA: Lec 6 (p. 22–35) SA: Lec 7 (p. 1, 3–10, 16)	2019 (Q3c), 2021 (Q2b), 2023 (Q3d), 2024 (Q1d, Q3e, Q4a, Q4b), 2025 (Q2d, Q8c)
7	Flood Proofing Strategies, Considerations & FEMA Methods • Strategy considerations (hazard analysis, site/building traits, FPE, appearance, accessibility, cost) • FEMA's 6 flood proofing methods (elevation, wet/dry proofing, relocation, levees/floodwalls, demolition) • Coastal/char strategies in Bangladesh; pros & cons	5 / 6	SB: Lec 7 (p. 7–50)	2021 (Q6b, Q7a), 2022 (Q5b), 2023 (Q6b), 2024 (Q5a, Q7d), 2025 (Q6c, Q7c)
8	Dynamic River Adjustment & Lane's Balance ($Q_{s}d\propto Q_{w}S$) • Morphological response (aggradation/degradation) to dams, clear-water release, water/sediment diversions, confluences, off-takes, floods, and landslides • Quantitative pre/post-development calculation: $a(b/c{)}^{1/3}=d·e$ • Limitations of Lane's relationship	5 / 6	SA: Lec 8 (p. 1–16, 21–23)	2021 (Q3d), 2022 (Q3b, Q6e), 2023 (Q4a), 2024 (Q8d), 2025 (Q3b, Q8d)
9	Complex Pier Scour Theory & Effective Diameter ($b_e$) • Complex pier definition & components (pier stem, pile cap, pile group) • Cases I–IV of pile cap exposure & why complex pier scour > normal pier scour • Equivalent/effective pier diameter calculation for bed-level pile cap	5 / 6	SA: Lec 10 (p. 6–16, 24–25, 27)	2019 (Q4b), 2022 (Q6b), 2023 (Q4e, Q8b), 2024 (Q4c), 2025 (Q4b, Q4d)
10	Causes, Types & Factors of Flooding in Bangladesh • Geographical, physiographic & hydro-meteorological factors (mountains/orographic rain, lower riparian 7% GBM area, 80% flat floodplain, peak synchronization, tidal backwater) • 1998 flood causes, major flood types, flash flood benefits, and BD river network	5 / 6	SB: Lec 1 (p. 7–14, 25–41)	2019 (Q5b, Q5c), 2022 (Q7a, Q8b), 2023 (Q5a, Q6a), 2024 (Q5b, Q8c), 2025 (Q6a)
11	Hydraulic Structures: Dams, Reservoirs, Weirs, Barrages & Levees • Short notes: Flood wall & Levee, Gravity dam, Diversion dam • Dam classification by use/structure; Weir vs Barrage; Dam vs Weir • Reservoir storage zones, design factors, and causes of dam failure	5 / 6	SB: Lec 3 (p. 19–45) SB: Lec 4 (p. 21) SB: Lec 7 (p. 36–38)	2019 (Q6a, Q6b), 2021 (Q6a), 2022 (Q8a), 2024 (Q6a), 2025 (Q5a)
12	Flood Control vs Management: Structural, Non-Structural & Short/Long-Term Measures • Flood control vs flood management; 4 planning phases (mitigation, preparedness, response, recovery) • Short-term vs long-term measures; structural (6 types) vs non-structural (7 types) measures	5 / 6	SB: Lec 3 (p. 7–18, 46–47) SB: Lec 6 (p. 50–52, 58)	2019 (Q5a), 2021 (Q5a), 2023 (Q6a), 2024 (Q6c), 2025 (Q5c, Q7b)
13	Flow Regimes, Bedforms & Roughness (Grain vs Form) • Lower, transition, and upper flow regime characteristics & bedform sequence • Why upper regime bedforms (antidunes) rarely occur in nature ($Fr>1$) • Grain roughness vs form roughness and Manning's $n$ variation across regimes	5 / 6	SA: Lec 6 (p. 1–21)	2019 (Q1b), 2022 (Q3a), 2023 (Q3a, Q3b), 2024 (Q3c), 2025 (Q1e)
14	Floodplain Zoning & Flood Mapping • Floodplain & flood zoning definitions; zoning classes by annual flood probability (Zones 1, 2, 3a, 3b & FEMA zones) • Zoning approaches (historic, conventional, modeling), required data, flood maps (FIRM), and pros/cons	5 / 6	SB: Lec 8 (p. 6–20)	2019 (Q7b), 2021 (Q6c), 2022 (Q7b), 2023 (Q7b), 2024 (Q6d)
15	Meandering Hypotheses, Pool-Riffle & Helical Current • 5 theories/hypotheses of meander formation (Coriolis, disturbance, excess energy, secondary flow, wave oscillation) • Pool-riffle cross-sections, helical flow & point bars, and pool-spacing vs meander length derivation	4 / 6	SA: Lec 2 (p. 5) SA: Lec 3 (p. 9–24)	2019 (Q3a), 2022 (Q2a), 2024 (Q2c, Q2d), 2025 (Q1c, Q4c)
16	Channel Stability & Planform Stability Ratios ($P{S}_1,P{S}_2$) • Parameters determining relative river stability (Schumm's 5 patterns) • Why meandering rivers are more stable than braided rivers • How sediment load type affects stability; force ratios $P{S}_1$ and $P{S}_2$	4 / 6	SA: Lec 3 (p. 13) SA: Lec 4 (p. 1–8)	2022 (Q2b), 2023 (Q2a), 2024 (Q2a), 2025 (Q2c)
17	Incipient Motion Theory: Shields Diagram & Hjulström Curve • Shields diagram: erosion of cohesive (clay/silt) vs non-cohesive (sand/gravel) beds • Proof that critical shear stress for coarse grains depends only on diameter (${\tau }_c\cong 970d$) • Hjulström curve: erosion vs suspension vs deposition velocity gap	4 / 6	SA: Lec 5 (p. 8–20)	2019 (Q3b), 2021 (Q2c, Q3b), 2024 (Q2b), 2025 (Q3a)
18	Incipient Motion / Shields Parameter (${\tau }^{*}$) Calculation (Math) • Given velocity, Chezy $C$, slope, and $d_{50}$: check bed erodibility (${\tau }_0$ vs ${\tau }_c$), find minimum non-erodible grain size, textural class, or maximum stable discharge	4 / 6	SA: Lec 5 (p. 3, 12–13, 18, 21–22) SA: Lec 6 (p. 23)	2022 (Q2d), 2023 (Q2e), 2024 (Q3d), 2025 (Q2e)
19	Land & Watershed Management in Flood Mitigation • Watershed & land management definitions • Why land/watershed management is vital compared to structural defenses • Effects of land-use change (urbanization, floodplain roads/embankments, agriculture) on flood hazards	4 / 6	SB: Lec 6 (p. 7–19, 35–46, 58)	2021 (Q5b, Q7b), 2023 (Q7c), 2024 (Q7a), 2025 (Q5d)
20	Flood Forecasting and Warning Systems • Definitions of flood forecasting and flood warning • Roles of flood forecasting in flood management; data requirements & limitations in Bangladesh	4 / 6	SB: Lec 10 (p. 6–23)	2019 (Q8a), 2023 (Q5c), 2024 (Q7b), 2025 (Q6b)
21	Flood Hazard, Vulnerability, Damage Assessment & Risk Calculation • Hazard, exposure, vulnerability, and risk ($D=E·V,R=H·D$) definitions • Factors influencing flood hazard & damage; tangible vs intangible damages • Mathematical flood risk & embankment benefit calculation ($R_m=\sum H_n{D}_n$)	4 / 6	SB: Lec 3 (p. 12) SB: Lec 9 (p. 7–26, 41–47) SB: Lec 11 (p. 6–11)	2019 (Q5c, Q8b, Q8c), 2022 (Q7c), 2025 (Q5b, Q7b)
22	Hydraulic Geometry Equations & Power-Law Derivations • Hydraulic geometry power equations ($w=a{Q}^b,d=c{Q}^f,u=k{Q}^m;ack=1,b+f+m=1$) • Deriving width-discharge ($W=a{Q}^b$) or slope-discharge ($S=p{Q}^{-z}$) relations from field data tables	3 / 6	SA: Lec 2 (p. 16–21) SA: Lec 3 (p. 1–6, 17–18)	2019 (Q1c, Q2d), 2022 (Q1c), 2023 (Q1b, Q1c)
23	Longitudinal River Profile: Downstream Slope & Velocity Variation • 3 reasons why river slope decreases downstream ($S=S_0{e}^{-\alpha x}$: abrasion, deposition, tributary inflow) • Flashy river hydrograph; why velocity increases slightly downstream ($V\propto d^{2/3}$)	3 / 6	SA: Lec 1 (p. 4–6) SA: Lec 2 (p. 12, 24–26) SA: Lec 3 (p. 1–4)	2022 (Q1b), 2024 (Q1a), 2025 (Q2b)
24	Rouse Suspended Sediment Concentration Calculation (Math) • Compute suspended sediment concentration $C_y$ at elevation $y$ from reference concentration $C_a$ at $a$, flow depth $D$, slope $S$, and fall velocity $\omega$	3 / 6	SA: Lec 7 (p. 6–11) SA: Lec 6 (p. 26–36)	2022 (Q3d), 2023 (Q3e), 2025 (Q3c)
25	Contraction Scour at Bridge Sites • Contraction scour definition and why it is generally insignificant / when not considered in bridge scour calculations	3 / 6	SA: Lec 9 (p. 1, 4–7)	2021 (Q1b), 2022 (Q3c), 2023 (Q4c)
26	Revetments, Riprap vs Gabion & Nature-Based Bank Protection • Riprap vs gabion comparison; open-joint vs closed-joint revetment suitability • Soft / bio-engineering / nature-based solutions (NBS) pros and cons	3 / 6	SA: Lec 11 (p. 2, 27–35, 38–42, 47)	2022 (Q4a), 2023 (Q8c, Q8d), 2024 (Q1f)
27	Inland Navigation: Advantages, Factors & Improvement Methods • Why waterway transport is cheapest (cost, energy, emissions, safety) • Morphological & flow factors affecting navigability • 3 methods to achieve navigability (channel regulation, lock & dam, canalization)	3 / 6	SA: Lec 12 (p. 1–21)	2022 (Q4b, Q4c), 2023 (Q4d), 2024 (Q4d, Q8a)
28	Urban Flooding: Definition, Causes, Rural Comparison & Impacts • Urban flooding definition & triggers; floodwater vs stormwater (rural vs urban) • Impacts on economy, environment, public health, traffic, and livestock	3 / 6	SB: Lec 2 (p. 6–20) SB: Lec 11 (p. 7–10)	2021 (Q7b), 2024 (Q6b), 2025 (Q7a)
29	Flood Diversion Channels & Floodways • Diversion channel & floodway definitions and importance for flood control • Advantages and disadvantages of diversion channels; PMF vs SPF	3 / 6	SB: Lec 4 (p. 6–20)	2022 (Q5a), 2023 (Q6c), 2024 (Q5d)
30	Flood & Rainfall Frequency Analysis (Normal & Log-Normal) (Math) • Compute $T$-year flood/rainfall magnitude (50, 100, 150-yr) and exceedance probability from annual series	3 / 6	SB: Lec 9 (p. 35–38)	2021 (Q5c), 2022 (Q5c), 2023 (Q7a)
31	Economic Evaluation of Flood Mitigation Projects • 5 approaches: Cost/Benefit, Fixed Cost, Cost Effective, Multi-objective, Non-economic • Levee optimal design stage selection from damage-return period-cost table	3 / 6	SB: Lec 11 (p. 12–20)	2019 (Q7c), 2023 (Q5b), 2024 (Q7c)
32	Bankfull Discharge Definition, W/D Abrupt Change & Depth Calculation • Bankfull discharge definition; why $W/D$ ratio changes abruptly above bankfull • Determining bankfull depth from cross-section width-depth data (minimum $W/D$)	2 / 6	SA: Lec 2 (p. 22–23)	2021 (Q1d), 2024 (Q1b)
33	Shear Stress & Stream Power Proportionality Proofs • Stream power definition ($\mathrm{\Omega }=\rho gQS=Vw{\tau }_0$); prove ${\tau }_0\propto V^2$ and $\mathrm{\Omega }\propto V^3$	2 / 6	SA: Lec 5 (p. 1–3)	2019 (Q2c), 2022 (Q6c)
34	Dune Bedform Bed Load Transport Calculation (Math) • Estimate bed load $q_b=0.5v{\rho }_s(1-p)L\mathrm{\Delta }H$ from dune length, height, near-bed velocity, and porosity	2 / 6	SA: Lec 7 (p. 13–14)	2021 (Q2d), 2024 (Q4e)
35	Meyer-Peter & Müller (MPM) Gravel Bed Load Calculation (Math) • Compute gravel bed load using simplified MPM equation $q_b=0.253({\tau }_0-{\tau }_{cr}{)}^{3/2}$ with ${\tau }_{cr}=970D$	2 / 6	SA: Lec 7 (p. 15)	2019 (Q3e), 2025 (Q8e)
36	Lacey–Inglis Scour Depth & Pier Scour Countermeasures • Lacey–Inglis maximum scour depth calculation ($D_{se}=2.0D_{LQ}$) & limitations • Sacrificial piles as flow-altering pier scour countermeasures	2 / 6	SA: Lec 10 (p. 26–31)	2019 (Q4f), 2025 (Q4c)
37	Morphological Consequences of a Meander Cut-Off • Slope steepening between cut-off points A and B, upstream headward erosion from A, downstream deposition from B	1 / 6	SA: Lec 12 (p. 22–25)	2023 (Q8e)

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2. Mathematical & Numerical Problem Archetypes

All numerical problems across the 6 exams fall into 10 specific archetypes. The formulas below match the exact notation and equations taught in the lecture slides.

Quick Reference Summary

#	Numerical Archetype	Freq.	Exact Lecture Slide Reference	Appeared In
1	Shields Parameter (${\tau }^{*}$) Bed Erodibility	4 / 6	SA: Lec 5 (p. 3, 12–13, 21–22), SA: Lec 6 (p. 23)	2022 (Q2d), 2023 (Q2e), 2024 (Q3d), 2025 (Q2e)
2	Hydraulic Geometry Log-Log Power-Law Fit	4 / 6	SA: Lec 2 (p. 17, 21), SA: Lec 3 (p. 17–18)	2019 (Q1c, Q2d), 2022 (Q1c), 2023 (Q1c), 2024 (Q2d)
3	Rouse Suspended Sediment Concentration	3 / 6	SA: Lec 7 (p. 6–11), SA: Lec 6 (p. 26–36)	2022 (Q3d), 2023 (Q3e), 2025 (Q3c)
4	Quantitative Lane's Relation ($a(b/c{)}^{1/3}=de$)	3 / 6	SA: Lec 8 (p. 6–10)	2021 (Q3d), 2022 (Q6e), 2024 (Q8d)
5	Flood / Rainfall Frequency (Normal & Log-Normal)	3 / 6	SB: Lec 9 (p. 35–38)	2021 (Q5c), 2022 (Q5c), 2023 (Q7a)
6	Dune Bedform Bed Load Transport	2 / 6	SA: Lec 7 (p. 13–14)	2021 (Q2d), 2024 (Q4e)
7	Complex Pier Effective Diameter ($b_e$)	2 / 6	SA: Lec 10 (p. 13, 25, 27)	2023 (Q4e), 2025 (Q4d)
8	Meyer-Peter & Müller (MPM) Gravel Bed Load	2 / 6	SA: Lec 7 (p. 15)	2019 (Q3e), 2025 (Q8e)
9	Flood Risk ($R=\sum H_n{D}_n$) & Levee B/C	3 / 6	SB: Lec 9 (p. 23–25), SB: Lec 11 (p. 19–20)	2019 (Q7c, Q8c), 2025 (Q5b)
10	Bankfull Depth ($W/D$) & Lacey–Inglis Scour	2 / 6	SA: Lec 2 (p. 22–23), SA: Lec 10 (p. 26–28)	2019 (Q4f), 2021 (Q1d)

Core Formulas & Solution Steps

1. Shields Parameter (${\tau }^{*}$) Bed Erodibility — SA: Lec 5 (p. 3, 12–13, 21–22)

   $${\tau }_0=\rho ghS=\rho g{\left(\frac{V}{C}\right)}^2,{\tau }_c={\tau }^{*}g({\rho }_s-\rho )d_{50}$$

   • Bed erodes if ${\tau }_0>{\tau }_c$. For minimum non-erodible size or maximum stable discharge $Q_{\max }=WhC\sqrt{hS}$, set ${\tau }_0={\tau }_c$. Use SA: Lec 6 (p. 23) or SA: Lec 5 (p. 18) for grain size textural classification.

2. Hydraulic Geometry & Meander Power-Law Fitting — SA: Lec 2 (p. 17, 21) & SA: Lec 3 (p. 17–18)

   $$W=a{Q}^b,S=p{Q}^z,SP=k{W}^n⟹M_L=2·SP$$

   • Transform to linear form ($\log W=\log a+b\log Q$) and apply linear regression or log-log plotting on the given data table.

3. Rouse Suspended Sediment Concentration Profile — SA: Lec 7 (p. 6–11)

   $$\frac{C}{C_a}={\left[\left(\frac{D-y}{y}\right)\left(\frac{a}{D-a}\right)\right]}^{R_n},R_n=z=\frac{\omega }{\kappa u_{*}},u_{*}=\sqrt{ghS}=\frac{\sqrt{g}}{C}V$$

   • With $\kappa =0.40$: $R_n>2.5$ (bed load), $1.8<R_n<2.5$ (partial suspension), $R_n<1.8$ (full suspension), $R_n<0.25$ (wash load). If fall velocity $\omega$ is not given directly, find it from $d_{50}$ using Stokes/impact law or the chart in SA: Lec 6 (p. 30–36).

4. Quantitative Lane's Relation (Pre- vs Post-Development) — SA: Lec 8 (p. 6–10)

   $$Q_s{\left(\frac{d_s}{y}\right)}^{1/3}\propto Q_w{S}_0⟹a{\left(\frac{b}{c}\right)}^{1/3}=d·e$$

   • Where $a=Q_{s2}/Q_{s1}$, $b=d_{s2}/d_{s1}$, $c=y_2/y_1$, $d=Q_{w2}/Q_{w1}$, and $e=S_{o2}/S_{o1}$. Solve for $e$: if $e>1$, downstream slope increases (aggradation); if $e<1$, downstream slope decreases (degradation).

5. Dune Bedform Bed Load Transport — SA: Lec 7 (p. 13–14)

   $$q_b=0.5v{\rho }_s(1-p)L\mathrm{\Delta }H,Q_b=q_b·W$$

   • Where $v$ is near-bed migration velocity (given as a percentage of mean velocity $V=\frac{1}{n}{h}^{2/3}{S}^{1/2}$ or $Q/Wh$), ${\rho }_s\approx 2650\text{kg}m{\text{[PARSE ERROR: Undefined("RBrace")]}}^3$, $p$ is porosity, $L$ is dune length, and $\mathrm{\Delta }H$ is dune height.

6. Effective Pier Diameter for Complex Piers ($b_e$) — SA: Lec 10 (p. 13, 25, 27)

   $$b_e=b\left(\frac{d+Y}{d+b^{*}}\right)+b^{*}\left(\frac{b^{*}-Y}{b^{*}+d}\right)$$

   • Where $b$ is normal pier width, $b^{*}$ is pile cap width, $d$ is hydraulic flow depth (found via Manning's equation $Q=\frac{1}{n}W{d}^{5/3}{S}^{1/2}$), and $Y$ is distance from bed to top of pile cap ($Y=0$ when pile cap is placed at bed level).

7. Meyer-Peter & Müller (MPM) Gravel Bed Load — SA: Lec 7 (p. 15)

   $$q_b=0.253({\tau }_0-{\tau }_{cr}{)}^{3/2},{\tau }_0=\rho ghS,{\tau }_{cr}=970D,Q_s=q_b·W$$

   • Where $D=d_{50}$ in meters, ${\tau }_0$ and ${\tau }_{cr}$ are in $\text{N}m{\text{[PARSE ERROR: Undefined("RBrace")]}}^2$, and $q_b$ is in $\text{kg}(s\text{[PARSE ERROR: Undefined("RBrace")]}·\text{m}\text{[PARSE ERROR: Undefined("RBrace")]}$.

8. Flood Risk ($R_m$) & Levee Benefit-Cost Optimization — SB: Lec 9 (p. 23–25) & SB: Lec 11 (p. 19–20)

   $$R=H·D=\frac{1}{T}D,R_m=\sum H_n{D}_n=0.1D_{10}+0.05D_{20}+0.02D_{50}+0.01D_{100}$$

   • Annual project benefit = $\mathrm{\Delta }{R}_m=R_{m,\text{without}}-R_{m,\text{with}}$. For levee stage optimization (2019 Q7c, SB: Lec 11 p. 19–20), compute incremental expected annual benefit $\mathrm{\Delta }B=\mathrm{\Delta }\text{Loss}\times \overline{P}$ and choose the stage maximizing net benefit / $B/C$ ratio.

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3. Questions Grouped by Lecture Material

Every past exam question is mapped below to its exact lecture PDF and slide page range, ordered by slide page number within each lecture for rapid skimming alongside the slides.

Section A: River Engineering & River Mechanics (12 Lectures)

SA Lecture 1: Rivers, Alluvial Rivers & Planform Classification

• File: SA/EWCE 461-Lec1.pdf (29 pages)
• Key Topics: River subsystems (collecting, transporting, dispersing) & zones (erosional, transport, depositional), longitudinal profile, delta vs estuary, drainage patterns, stream order, classification (substrate, groundwater table, flow duration, sediment load, planform), sinuosity, multichanneledness, Planform Index (PFI).

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 4–6	Longitudinal profile zones & how gradient, velocity, discharge, and channel size change downstream	2022 (Q1b, 6m), 2024 (Q1a, 5m), 2025 (Q2b, 6m)
p. 7, 11–12	Definitions of floodplain, natural levee, terrace, thalweg, tributary, and distributary	2024 (Q6d, 6m)
p. 17–18	Definition and self-forming/morphologically unstable characteristics of an alluvial river	2025 (Q1a, 5m)
p. 21, 23–24	Classification of rivers by sediment load (suspended-load, mixed-load, bed-load) and their stability	2022 (Q2b, 5m), 2023 (Q2a, 5m)
p. 25–27	Classification by morphology/pattern using sinuosity and multichanneledness (straight, braided, meandering, anastomosing)	2019 (Q1a, 6m), 2025 (Q1a, 5m)
p. 28–29	Planform Index (PFI) and braiding evolution of the Jamuna River	2024 (Q8c, 8m)

SA Lecture 2: Channel Patterns, Hydraulic Geometry, Bankfull & River Slope

• File: SA/EWCE 461-Lec2.pdf (26 pages)
• Key Topics: Ganges sinuosity, channel patterns (straight, meandering, braided), pool-riffle sketch, pattern controlling variables (slope, sediment load, sinuosity, $W/D$ ratio, discharge), flashy vs normal rivers, hydraulic geometry ($w=a{Q}^b,d=c{Q}^f,u=k{Q}^m$), bankfull discharge & minimum $W/D$ depth calculation, longitudinal slope reduction ($S=S_0{e}^{-\alpha x}$) and 3 reasons slope decreases downstream.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 3–6	What is river/channel pattern; characteristics of straight, meandering (pools & riffles), and braided streams	2019 (Q1a, 6m), 2023 (Q1a, 12m), 2024 (Q2c, 5m), 2025 (Q1a, 5m)
p. 7–11, 13–15	Four variables affecting channel pattern (slope, sediment load, sinuosity, $W/D$ ratio) and discharge; how pattern changes with slope for a given discharge	2019 (Q2a, 10m), 2021 (Q1a, 5m), 2022 (Q1a, 8m), 2023 (Q1a, 12m), 2024 (Q1c, 5m), 2025 (Q1b, 5m; Q2a, 5m)
p. 12	Definition of a flashy river with hydrograph figure (Halda vs Meghna river)	2025 (Q2b, 6m)
p. 16–20	What is hydraulic geometry; at-a-station vs downstream hydraulic geometry equations ($w=a{Q}^b,d=c{Q}^f,u=k{Q}^m$)	2023 (Q1b, 5m)
p. 21	Math: Develop width-discharge relationship ($W=a{Q}^b$) from tabular river data	2019 (Q1c, 14m), 2022 (Q1c, 16m)
p. 22–23	Define bankfull discharge; why $W/D$ ratio changes abruptly beyond bankfull; Math: determine bankfull depth from width-depth table (minimum $W/D$)	2021 (Q1d, 12m), 2024 (Q1b, 5m)
p. 24–26	How and why river slope changes along the longitudinal profile ($S=S_0{e}^{-\alpha x}$); 3 reasons slope decreases downstream (abrasion, upper-basin erosion/valley deposition, tributary inflow)	2022 (Q1b, 6m), 2024 (Q1a, 5m)

SA Lecture 3: Derived Hydraulic Relations, Meandering Theories & Helical Flow

• File: SA/EWCE-461-Lec3.pdf (24 pages)
• Key Topics: Downstream variation of $n,f,D_{50},C$, and velocity $V$; effect of $S$, form ratio $w/d$ (bank cohesiveness), and sediment size on pattern; 5 theories/hypotheses of meandering; meander geometry ($r_c,\mathrm{\Lambda },M_L$) & pool-spacing relationship; pool-riffle cross-sections, point bars, helical current, and superelevation.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 1–4	Derived hydraulic geometry relations and how velocity changes downstream as discharge increases ($V\propto d^{2/3}$ increases slightly)	2023 (Q1b, 5m), 2025 (Q2b, 6m)
p. 5–8	Effect of slope, sediment size, and bank/bed cohesiveness (% silt-clay) on width/depth ratio ($w/d=255M^{-1.08}$) and river pattern	2021 (Q1a, 5m), 2022 (Q1a, 8m), 2023 (Q1a, 12m), 2024 (Q1c, 5m), 2025 (Q1b, 5m; Q2a, 5m)
p. 9–11	Theories / hypotheses proposed for the formation of meanders (Coriolis force, disturbance, excess energy, secondary flow, wave oscillation)	2019 (Q3a, 6m), 2022 (Q2a, 6m), 2025 (Q1c, 5m)
p. 13	Predictability of erosion and deposition regions in a meandering river vs unpredictable braided river	2023 (Q2a, 5m), 2025 (Q2c, 6m)
p. 1, 4–6, 17	Math: Develop slope-discharge relationship ($S=p{Q}^{-z}$) from tabular river data	2019 (Q2d, 10m), 2023 (Q1c, 13m)
p. 14–18	Math: Derive meander length and width relationship from pool-to-pool spacing data ($SP=a{W}^b,M_L=2·SP$)	2024 (Q2d, 15m)
p. 19–24	Pool and riffle planform figure and cross-sections (symmetrical vs asymmetrical); point bar and helical current (secondary flow)	2024 (Q2c, 5m), 2025 (Q4c, 2m)

SA Lecture 4: Channel Stability, Planform Stability Ratios & Sediment Load Modes

• File: SA/EWCE-461-Lec4.pdf (22 pages)
• Key Topics: Causes of braiding, channel stability continuum (Patterns 1–5, Schumm), effect of sediment load type on stability, planform stability ratios ($P{S}_1,P{S}_2$), sediment load classifications (physical nature, bed presence, transport mode), dissolved load, wash load, suspended load, bed load, vertical grain-size & concentration profiles.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 1–6	Parameters determining relative stability of rivers; how sediment load type affects stability; why meandering rivers are more stable than braided rivers	2022 (Q2b, 5m), 2023 (Q2a, 5m), 2025 (Q2c, 6m)
p. 7–8	How planform stability ratios ($P{S}_1$ and $P{S}_2$) determine river stability	2024 (Q2a, 6m), 2025 (Q2c, 6m)
p. 9–13, 19–21	Classification of sediment load (by physical nature, presence in bed, and mode of transport); differences between wash load, bed-material load, bed load, suspended bed-material load, and suspended load	2019 (Q2b, 6m), 2021 (Q1c, 8m), 2022 (Q2c, 8m), 2023 (Q2b, 5m), 2024 (Q3a, 5m), 2025 (Q1d, 5m)
p. 10–13, 17	Why there is no sharp demarcation between suspended load and bed load (interchangeable nature) with figure	2023 (Q2c, 5m), 2024 (Q3b, 5m)
p. 14–16	What is dissolved load and why it is not part of the sediment load / channel processes	2023 (Q2d, 5m; Q3d, 5m)
p. 17–19, 22	How size and concentration of suspended sediment vary logarithmically with depth ($d_{10},d_{50},d_{90}$ / silt vs sand profiles)	2024 (Q1d, 5m), 2025 (Q2d, 5m)
p. 19–20	Why wash load never settles down (Brownian motion / thermal agitation); why bed load is capacity-dependent and wash/suspended load is supply-dependent	2021 (Q1c, 8m), 2022 (Q2c, 8m), 2023 (Q3c, 5m)

SA Lecture 5: Forces in a River, Stream Power, Hjulström & Shields Diagram

• File: SA/EWCE-461-Lec5.pdf (22 pages)
• Key Topics: Bed shear stress (${\tau }_0=\rho ghs$), stream power ($\mathrm{\Omega }=\rho gQs$), proofs that ${\tau }_0\propto V^2$ and $\mathrm{\Omega }\propto V^3$, Strickler's equation ($n=0.047d_{{50}^{1/6}}$), competence vs capacity, fall velocity, incipient motion force/moment balance, Hjulström diagram, Shields diagram & parameter (${\tau }^{*}$), erodibility calculations.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 2–3	Define stream power; prove that shear stress ${\tau }_0\propto V^2$ and stream power $\mathrm{\Omega }\propto V^3$	2019 (Q2c, 4m), 2022 (Q6c, 4m)
p. 4	Differences between competence and capacity; definition of fall velocity	2019 (Q3c, 6m), 2021 (Q2b, 7m), 2023 (Q2d, 5m; Q3d, 5m), 2025 (Q8c, 2m)
p. 12–13, 19–20	Prove that critical shear stress / force required to erode coarse-grained sediment is a function of only sediment diameter (${\tau }_c=0.06dg({\rho }_s-\rho )\cong 970d$)	2021 (Q3b, 5m), 2024 (Q2b, 4m)
p. 14, 18–20	Explain with Shields diagram the erosion process of cohesive and non-cohesive bed material	2019 (Q3b, 6m)
p. 15–17, 20	Hjulström diagram: why higher velocity is needed to erode sediment than keep it in suspension; how velocity difference between erosion and deposition changes with grain size; why wash load never settles	2021 (Q2c, 5m), 2023 (Q3c, 5m), 2025 (Q3a, 6m)
p. 3, 12–13, 18, 21–22	Math: Shields parameter (${\tau }^{*}$) erodibility check (${\tau }_0$ vs ${\tau }_c$), minimum non-erodible bed material size, textural class, and maximum stable discharge	2022 (Q2d, 11m), 2023 (Q2e, 10m), 2024 (Q3d, 10m), 2025 (Q2e, 8m)

SA Lecture 6: Regimes of Flow, Bedforms, Roughness & Fall Velocity

• File: SA/EWCE-461-Lec6.pdf (37 pages)
• Key Topics: Regimes of flow (lower, transition, upper), bedform progression with stream power (plane bed, ripples, dunes, washed-out dunes, standing waves, antidunes), grain roughness vs form roughness, sediment size classification scale, Stokes & inertial settling velocity derivations, effect of particle sphericity/shape factor on fall velocity.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 1–17	What is flow regime; major differences between lower and upper flow regimes; how bedforms and Manning's $n$ resistance vary across regimes; why upper regime bedforms rarely occur in nature	2019 (Q1b, 10m), 2023 (Q3a, 7m; Q3b, 3m), 2024 (Q3c, 5m), 2025 (Q1e, 5m)
p. 18–21	Define grain roughness and form roughness; which is dominant and when	2022 (Q3a, 5m), 2023 (Q3b, 3m), 2025 (Q1e, 5m)
p. 23	Sediment size classification scale (clay, silt, sand, gravel, cobbles, boulders)	2025 (Q2e, 8m)
p. 22, 24–35	Settling/fall velocity mechanics and how particle sphericity/shape factor affects fall velocity ($C_D$ vs $R{e}_p$ and settling velocity graphs)	2019 (Q3c, 6m), 2022 (Q3d, 14m), 2024 (Q3e, 5m)

SA Lecture 7: Sediment Transport Rates, Rouse Profile, Dune Bed Load & MPM Equation

• File: SA/EWCE-461-Lec7.pdf (27 pages)
• Key Topics: Complexity of sediment transport estimation, bed shear stress & shear velocity ($u_{*}$), Rouse equation & Rouse number ($R_n$) suspension criteria, worked Rouse concentration calculation, bed load from dune dimensions ($q_b=0.5v{\rho }_s(1-p)L\mathrm{\Delta }H$), Meyer-Peter & Müller (MPM) gravel bed load equation ($q_b=0.253({\tau }_0-{\tau }_{cr}{)}^{3/2}$), total load formulas (Ackers-White, Engelund-Hansen).

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 1, 5, 17–18, 24	Complexity and uncertainties in the determination of suspended sediment load ($q_s=\int cudy$)	2024 (Q4b, 5m)
p. 4, 16	Definition of shear velocity ($u_{*}=\sqrt{{\tau }_b/{\rho }_w}$) and difference between shear velocity and fall velocity	2021 (Q2b, 7m), 2023 (Q3d, 5m), 2025 (Q8c, 2m)
p. 6–10	Rouse equation & Rouse number ($R_n=\omega /\kappa u_{*}$); how $R_n$ distinguishes suspension status and controls vertical sediment distribution	2019 (Q3c, 6m), 2021 (Q2b, 7m), 2024 (Q1d, 5m; Q4a, 5m), 2025 (Q2d, 5m)
p. 6–11	Math: Calculate suspended sediment concentration $C_y$ at elevation $y$ from reference concentration $C_a$ at $a$ using Rouse equation	2022 (Q3d, 14m), 2023 (Q3e, 10m), 2025 (Q3c, 16m)
p. 13–14	Math: Estimate bed load transport rate from dune bedform length $L$, height $\mathrm{\Delta }H$, near-bed velocity $v$, and porosity $p$	2021 (Q2d, 13m), 2024 (Q4e, 10m)
p. 15	Math: Calculate gravel-bed river bed load transport rate using Meyer-Peter & Müller (MPM) equation $q_b=0.253({\tau }_0-{\tau }_{cr}{)}^{3/2}$	2019 (Q3e, 7m), 2025 (Q8e, 6m)

SA Lecture 8: Dynamic Adjustment of Rivers — Lane's Relationship, Aggradation & Degradation

• File: SA/EWCE-461-Lec8.pdf (30 pages)
• Key Topics: Lane's qualitative relation ($Q_{s}d\propto Q_{w}S$), limitations of Lane's balance, quantitative modified Lane's relation ($a(b/c{)}^{1/3}=d·e$), aggradation and degradation causes & differences, morphological response to dams, clear-water release (armouring), water/sediment diversions, confluences, off-takes, floods, landslides, earthquakes, Khowai River case study.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 3	Limitations of Lane's relationship on river equilibrium (non-quantitative, no timeframe, ignores planform/cross-section geometry)	2025 (Q8d, 4m)
p. 6–10	Math: Quantitative Lane's relation ($a(b/c{)}^{1/3}=d·e$) for downstream morphological changes after reservoir retention, irrigation diversion, or landslide	2021 (Q3d, 13m), 2022 (Q6e, 10m), 2024 (Q8d, 8m)
p. 5, 11–16, 21–23	Expected morphological changes (aggradation/degradation): upstream & downstream of a dam, release of clear water, water supply diversion, flood discharge increase, tributary confluence, and distributary off-take	2022 (Q3b, 6m), 2023 (Q4a, 6m), 2025 (Q3b, 8m)

SA Lecture 9: River Scour Fundamentals (General, Contraction, Pier & Abutment Scour)

• File: SA/EWCE-461-Lec9.pdf (36 pages)
• Key Topics: General scour (aggradation/degradation) vs localized scour (contraction + local scour), why contraction scour is minor at bridge sites, horseshoe and wake vortex mechanisms, 6 factors affecting local scour (velocity ratio $V/V_c$, flow depth, narrow vs wide pier width, grain size $d_{50}$, angle of attack, pier shape), pier vs abutment scour comparison, clear-water vs live-bed scour.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 1–4	What is local scour & types of scour; difference between scour and long-term degradation	2019 (Q3d, 5m), 2025 (Q8c, 2m)
p. 4–7	What is contraction scour and why it is generally not significant / when not considered at bridge sites	2021 (Q1b, 5m), 2022 (Q3c, 5m), 2023 (Q4c, 4m)
p. 8–11, 14, 34–36	Scour process around a bridge pier; differences between horseshoe vortex and wake vortex; critical scour velocity ($V_c$) and equilibrium scour depth ($d_s$)	2021 (Q2a, 5m), 2023 (Q4b, 6m), 2025 (Q4a, 8m)
p. 11–24	Factors affecting local pier scour: roles of flow depth and pier diameter, wide ($y/b_p\text{[PARSE ERROR: Undefined("Command("le")")]}0.2$) vs narrow ($y/b_p\text{[PARSE ERROR: Undefined("Command("ge")")]}1.4$) piers, sediment size ($d_{50}$), and angle of attack ($\theta$)	2019 (Q4a, 4m), 2021 (Q3a, 6m), 2024 (Q1e, 5m), 2025 (Q1f, 5m)
p. 12, 25–28	Why pier scour depth is generally higher than abutment scour depth	2019 (Q4c, 4m), 2025 (Q4a, 8m)
p. 29–33	Difference between clear-water scour and live-bed scour; which is higher and why	2019 (Q4e, 4m), 2022 (Q6a, 6m), 2025 (Q8c, 2m)

SA Lecture 10: Advanced Scour — Complex Piers, Lacey–Inglis Method & Countermeasures

• File: SA/EWCE-461-Lec10.pdf (38 pages)
• Key Topics: Clear-water vs live-bed scour (review), normal vs complex piers (column, pile cap, pile group), Cases I–IV of pile cap elevation, effective pier diameter formula ($b_e$), HEC-18 (CSU) scour equation, normal vs complex pier scour comparison, Lacey–Inglis scour depth method, armoring vs flow-altering countermeasures (collars, sacrificial piles).

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 1–5	Clear-water scour vs live-bed scour comparison and Laursen critical velocity formula	2019 (Q4e, 4m), 2022 (Q6a, 6m), 2025 (Q8c, 2m)
p. 6–15, 24–25	Complex pier definition & 3 components; Cases I–IV when a normal pier must be treated as a complex pier; why effective pier diameter ($b_e$) is needed and why complex pier scour > normal pier scour	2019 (Q4b, 5m), 2022 (Q6b, 6m), 2023 (Q8b, 4m), 2024 (Q4c, 5m), 2025 (Q4b, 5m)
p. 13, 25, 27	Math: Calculate effective/equivalent pier diameter ($b_e$) for a bridge pier with a pile cap placed at river bed level	2023 (Q4e, 8m), 2025 (Q4d, 9m)
p. 26–28	Math & Theory: Calculate maximum scour depth by Lacey–Inglis method ($D_{LQ}=0.47(Q/f{)}^{1/3},D_{se}=2.0D_{LQ}$) and state limitations	2019 (Q4f, 8m)
p. 29–31	Explain sacrificial piles as flow-altering bridge pier scour countermeasures	2025 (Q4c, 2m)

SA Lecture 11: River Training & Bank Protection Works

• File: SA/EWCE- 461-Lec11.pdf (47 pages)
• Key Topics: River training objectives, active (transverse) vs passive (longitudinal) structures, hardcore vs softcore (nature-based/bioengineering) works, spurs/groynes (slack zone, permeable vs impermeable, attracting/deflecting/repelling orientation, head shapes, length & spacing design), guide banks & launching aprons, porcupines, revetments (open vs closed joint, riprap vs gabion, CC blocks, geobags), bandals.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 1, 3–6	Differences between active (transverse) and passive (longitudinal) river training structures with examples	2022 (Q6d, 4m), 2023 (Q8a, 4m)
p. 2, 38–42, 47	Soft approach / Nature-based Solutions (NBS) / bioengineering in bank protection: advantages and disadvantages	2022 (Q4a, 8m), 2023 (Q8d, 5m)
p. 4, 6–12	Spurs/groynes: slack flow zone definition, how spurs protect banks and develop a new bankline, permeable vs impermeable groynes, and orientation types (attracting, deflecting, repelling)	2019 (Q4d, 5m), 2021 (Q3c, 6m), 2024 (Q1f, 5m), 2025 (Q4c, 2m; Q8a, 5m; Q8c, 2m)
p. 11–14	Design considerations of groynes (length, spacing, number) and application for flood management in Bangladesh	2019 (Q6c, 10m), 2022 (Q8c, 15m)
p. 29	Difference between open-joint (flexible) and close-joint (rigid) revetments and where each is suitable	2023 (Q8c, 5m)
p. 30–32	Definitions and differences between Riprap and Gabion (stone size, bank slope, wire cage, cost)	2022 (Q4a, 8m), 2024 (Q1f, 5m)
p. 43–46	Bandals for bank protection and dry-season navigational channel improvement	2025 (Q4c, 2m)

SA Lecture 12: Inland Navigation, Cut-Offs & River Dredging

• File: SA/EWCE 461-Lec12.pdf (46 pages)
• Key Topics: Advantages of inland waterway transport (cost, energy efficiency, ${\text{CO}}_2$, safety), morphological & flow factors affecting navigability, 3 methods of achieving navigability (channel regulation, lock & dam, canalization), meander cut-offs & morphological consequences, dredging types (hydraulic vs mechanical, cutter suction, capital vs maintenance), 4 phases of dredging, why dredging for navigation is unsustainable (headcutting, pit siltation, Gorai River case study).

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 1–8	Why riverine transport is the cheapest mode; advantages of inland navigation over road and rail	2022 (Q4c, 8m), 2024 (Q4d, 5m)
p. 12–16	Morphological factors (depth/draft, width, bend radius, blockage factor $A_c/A_v$) and flow factors (velocity, helical/transverse currents, shoals) affecting navigability	2022 (Q4b, 8m), 2023 (Q4d, 6m), 2025 (Q4c, 2m)
p. 16–21	Methods of achieving/improving navigability of a river (channel regulation, lock and dam, canalization)	2024 (Q8a, 6m)
p. 22–25	Morphological consequences of a meander cut-off with figure (slope steepening between A and B, upstream erosion, downstream deposition)	2023 (Q8e, 5m)
p. 24, 26–31	Hydraulic vs mechanical dredgers; capital vs maintenance dredging; 4 phases/processes of dredging (pretreatment, extraction, transport, disposal)	2022 (Q4c, 8m; Q4d, 6m), 2023 (Q8f, 7m), 2024 (Q7a, 2.5m; Q8b, 8m), 2025 (Q4c, 2m; Q8b, 7m)
p. 37–46	Why capital/navigation dredging is generally not sustainable with longitudinal profile figures (upstream nickpoint headcutting, pit sediment trapping, downstream hungry-water erosion, post-flood re-aggradation)	2022 (Q4d, 6m), 2024 (Q8b, 8m)

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Section B: Flood Management (11 Lectures)

SB Lecture 1: Overview of Floods, Types & Causes of Floods in Bangladesh

• File: SB/Lecture-1.pdf (42 pages)
• Key Topics: Flood definition, blessing of normal floods vs extreme floods, general flood types, geographical/physiographic/hydro-meteorological factors of flooding in Bangladesh (surrounded by mountains/orographic rain, lower riparian 7% of GBM basin, 80% flat floodplain, 230 linked rivers, synchronization of GBM peaks, Bay of Bengal tidal/wind backwater), 1998 & 2004 floods, 4 major flood types & 11 causes in Bangladesh.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 9, 12–14	Positive outcomes / blessings from normal and flash floods (soil moisture & alluvial silt fertility)	2022 (Q8b, 5m)
p. 10–24, 40	Major types of flood in Bangladesh (flash flood, drainage congestion/urban flood, monsoon river flood, coastal storm surge)	2023 (Q6a, 10m)
p. 25–39, 41	Geographical, physiographic, and hydro-meteorological factors responsible for floods in Bangladesh (climate, upstream terrain, siltation, peak synchronization, backwater effect)	2019 (Q5b, 8m), 2022 (Q7a, 10m), 2023 (Q5a, 10m), 2024 (Q5b, 10m), 2025 (Q6a, 10m)
p. 29–36	River system network of Bangladesh (~230 tributaries/distributaries of GBM) and Brahmaputra-Jamuna dominance	2019 (Q5c, 6m), 2024 (Q8c, 8m)

SB Lecture 2: Flood Process in Urban and Rural Areas

• File: SB/Lecture-2.pdf (22 pages)
• Key Topics: Urban drainage types (storm, sanitary, combined sewers; merits & demerits), floodwater (rural) vs stormwater (urban), urban flooding definition & triggers (impervious surfaces, urban vs natural watershed), natural & man-made causes, impacts of urban flooding (economy, environment, human health, traffic, livestock), preventive measures & models.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 8, 14–19	How urban flooding differs from rural flooding (floodwater vs stormwater, drainage area, imperviousness, and impacts)	2024 (Q6b, 10m)
p. 14, 16–19	Define urban flooding; explain the impacts of urban flooding (economic, environmental, human health, traffic, livestock)	2021 (Q7b, 12m), 2024 (Q6b, 10m), 2025 (Q7a, 10m)

SB Lecture 3: Flood Management Measures, Dams & Hydraulic Structures

• File: SB/Lecture-3.pdf (48 pages)
• Key Topics: Planning for flood management (mitigation, preparedness, response, recovery), short-term vs long-term measures, 5 factors on which flood damages depend, structural (6 types) vs non-structural (7 types) measures, Bangladesh flood policy & steps to minimize losses, dam parts & layout, dam classification (by structure, size, use, material), gravity dam, barrage, detention dam, dry dam, diversion dam, weir, saddle/check/coffer dams, features of BD flood control projects (FC, FCD, FCDI, submersible embankments).

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 7–8	Planning for flood management (pre-disaster mitigation, preparedness, disaster response, post-flood recovery)	2025 (Q5c, 8m)
p. 9–11, 16	Differentiate between flood control and flood management; illustrate short-term and long-term measures for flood management	2021 (Q5a, 13m), 2024 (Q6c, 8m), 2025 (Q7b, 5m)
p. 12	List the factors on which damages from a flood event depend (location, depth, duration, timing/crop calendar, extent)	2019 (Q5c, 4m), 2025 (Q7b, 5m)
p. 13–18, 46–47	Structural and non-structural measures for effective flood control and flood control approaches in Bangladesh	2019 (Q5a, 12m), 2023 (Q6a, 10m)
p. 19–24, 32	Dam and reservoir layout, storage zones of a reservoir, and basic reservoir design factors	2019 (Q6a, 10m), 2022 (Q8a, 10m)
p. 25, 31, 33–38	Types of dams according to use; differentiate between Weir and Barrage, and between Dam and Weir; causes of dam failure	2019 (Q6b, 10m), 2021 (Q6a, 10m), 2022 (Q8a, 10m)
p. 10, 14, 27–28, 35–37	Short notes on: (i) Flood wall and Levee, (ii) Gravity dam, (iii) Diversion dam	2024 (Q6a, 6m), 2025 (Q5a, 6m)

SB Lecture 4: Diversion Channels, Floodways & Floodwalls

• File: SB/Lecture-4.pdf (22 pages)
• Key Topics: Diversion channels & floodways (flood bypass channels), control structures, advantages and disadvantages of diversion channels, classification of river diversion (tunnel, conduit, channel, bypass, temporary vs permanent), design considerations & steps for flood bypass, floodwalls.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 6–10	Define flood diversion channel / floodway; importance, advantages, and disadvantages of diversion channels for flood management; PMF vs SPF	2022 (Q5a, 10m), 2023 (Q6c, 10m), 2024 (Q5d, 5m)
p. 21	Short note on Flood wall (vertical artificial barrier, floodgates, high-value property protection)	2024 (Q6a, 2m), 2025 (Q5a, 2m)

SB Lecture 5: Improvement of Channel Capacity by Dredging

• File: SB/Lecture-5.pdf (26 pages)
• Key Topics: Dredging & dredger definitions, purposes of dredging (channel deepening, maintenance, land reclamation, beach nourishment, mining), 3 steps of dredging (pretreatment, extraction, disposal), mechanical vs hydraulic dredging & equipment types, morphological and hydraulic response to dredging, environmental/biological impacts of dredging, capital (BWDB Gorai) vs maintenance (BIWTA) dredging in Bangladesh.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 7–9, 21–23	Purposes and impacts of dredging activities from different perspectives (flood management, morphological, environmental)	2019 (Q7a, 10m), 2021 (Q7c, 10m), 2022 (Q7d, 5m)
p. 10–12	Three steps / phases involved in the river dredging process (pretreatment, extraction, disposal)	2022 (Q4c, 4m), 2023 (Q8f, 7m), 2025 (Q8b, 7m)
p. 13, 17–20	Hydraulic dredging vs mechanical dredging	2024 (Q7a, 2.5m; Q8b, 8m)
p. 22	Morphological and hydraulic response due to dredging	2024 (Q5c, 5m)

SB Lecture 6: Land & Watershed Management for Flood Mitigation

• File: SB/Lecture-6.pdf (58 pages)
• Key Topics: Land management & flood mitigation, why land management is important compared to structural defenses, land-water fluxes, watershed definition & problems, watershed management components & design considerations, watershed classification & modeling (black-box, lumped, distributed), rainwater harvesting (RWH), impacts of land-use change on flood hazards (development interventions, floodplain roads/embankments, urbanization, agriculture), land-use & flood management planning processes.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 8–9, 58	Why land / watershed management plays a key role compared to other (structural) flood management measures	2021 (Q5b, 5m), 2023 (Q7c, 10m)
p. 12–17	Explain the term 'Watershed management' and its components	2021 (Q7b, 6m), 2024 (Q7a, 2.5m)
p. 35–46	Effect of land-use change processes (urbanization, floodplain roads/embankments, agricultural practices) on flood hazards	2025 (Q5d, 8m)
p. 49–55	Land-use planning and flood management planning processes	2025 (Q5c, 8m)

SB Lecture 7: Flood Proofing Strategies

• File: SB/Lecture-7.pdf (51 pages)
• Key Topics: Flood proofing definition & basic techniques, permanent/contingent/emergency measures, advantages & disadvantages of flood proofing, 7 considerations for developing a flood proofing strategy (hazard analysis, site traits, building traits, regulations, appearance, accessibility, cost), FEMA's 6 flood proofing methods (elevation, wet proofing, relocation, dry proofing, levees/floodwalls, demolition), emergency measures, Chars Livelihoods Programme (CLP) case study in Bangladesh.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 11–12	Advantages and disadvantages of flood proofing technology	2021 (Q7a, 8m), 2024 (Q7d, 7m)
p. 13–20	Considerations for developing a flood proofing strategy (flood hazard analysis, site & building characteristics, appearance, accessibility, human intervention, cost)	2021 (Q6b, 10m), 2022 (Q5b, 10m), 2023 (Q6b, 10m), 2024 (Q5a, 10m), 2025 (Q6c, 10m)
p. 21–39	Various flood proofing strategies outlined by FEMA (Elevation, Wet Flood Proofing, Relocation, Dry Flood Proofing, Levees & Floodwalls, Demolition)	2024 (Q6a, 2m), 2025 (Q5a, 2m; Q7c, 10m)
p. 42–50	Flood proofing processes and strategies for vulnerable char/coastal areas in Bangladesh	2022 (Q5b, 10m)

SB Lecture 8: Floodplain Zoning & Flood Mapping

• File: SB/Lecture-8.pdf (20 pages)
• Key Topics: Floodplain & flood zone definitions, flood zoning as a non-structural measure, advantages & disadvantages of flood zoning, flood maps (FIRM, FBFM, FHBM, DFIRM), flood zone classification by annual probability (Zones 1, 2, 3a, 3b) and FEMA risk categories (A, V, B, C, X, D), 3 approaches to flood zoning (historic, conventional, modeling), 7 data types required for flood zoning.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 6–11	Define floodplain, flood map (FIRM, FBFM, FHBM), and flood zoning; advantages and disadvantages of flood zoning ("Flood-plain zoning reduces the risk and cost of damages")	2019 (Q7b, 7m), 2021 (Q6c, 10m), 2022 (Q7b, 5m), 2023 (Q7b, 4m), 2024 (Q6d, 2m)
p. 12–17	Different flood zones classified based on annual flood occurrence probability (Zones 1, 2, 3a, 3b & FEMA zones) and their roles in flood management	2022 (Q7b, 5m), 2024 (Q6d, 4m)
p. 18–19	Approaches of flood zoning (historic, conventional, modeling) and data required for flood zoning	2019 (Q7b, 3m), 2023 (Q7b, 6m)

SB Lecture 9: Flood Hazard Mapping, Risk Analysis & Frequency Analysis

• File: SB/Lecture-9.pdf (55 pages)
• Key Topics: Flood risk, hazard, elements at risk, exposure, susceptibility, and vulnerability ($D=E·V,R=H·D$), 6 factors influencing flood hazard (area, depth, duration, velocity, rate of rise, timing), stage-damage curves, mathematical flood risk estimation ($R=\sum H_n{D}_n$), Sirajganj & Southwest Bangladesh case studies, flood frequency analysis (Normal, Log-Normal, P3, LP3, EV1).

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 7–12, 18–22	Comment on flood hazard, risk, exposure, susceptibility, and vulnerability; processes and parameters of flood damage assessment ($D=\sum E_i{V}_i$, stage-damage curves)	2019 (Q8b, 5m), 2022 (Q7c, 10m)
p. 13–17	Factors influencing flood hazard (inundation area, depth, duration, flow velocity, rate of water rise, time of occurrence)	2019 (Q8b, 5m)
p. 23–25	Math: Flood risk calculation ($R=H·D=D/T$ and weighted annual risk $R_m=\sum H_n{D}_n$) for island/floodplain communities and embankment risk-reduction benefit	2019 (Q8c, 6m), 2025 (Q5b, 8m)
p. 35–38	Math: Flood and rainfall frequency analysis using Normal and Log-Normal probability distributions ($T$-year flood/rainfall and exceedance probability)	2021 (Q5c, 12m), 2022 (Q5c, 10m), 2023 (Q7a, 10m)

SB Lecture 10: Flood Forecasting and Warning System

• File: SB/Lecture-10.pdf (23 pages)
• Key Topics: Definitions of flood forecasting and flood warning, role of flood forecasting in flood management, limitations of flood forecasting, data requirements (hydrological, morphological, meteorological, topographical; BWDB & BMD stations), flood forecasting model types (precipitation-driven, routing, combined, special case) & correlation techniques.

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 6–8	Define flood forecasting and flood warning; explain the role of flood forecasting in flood management	2023 (Q5c, 10m), 2024 (Q7b, 8m), 2025 (Q6b, 10m)
p. 8–23	Salient features, data requirements, models, and limitations of flood forecasting and warning as practiced in Bangladesh	2019 (Q8a, 10m)

SB Lecture 11: Flood Damage Assessment & Economic Evaluation

• File: SB/Lecture-11.pdf (22 pages)
• Key Topics: Tangible (direct urban/rural, indirect urban/rural) vs intangible flood damages, level of protection, 5 approaches for economic evaluation of flood mitigation projects (Cost/Benefit, Fixed Cost, Multi-objective, Cost Effective, Non-economic), worked levee stage benefit-cost optimization table & graph, disaster relief (short-term vs long-term recovery).

Slide Pages	Question / Concept Tested	Appeared Exams (Question & Marks)
p. 6–11	Differentiate between tangible (direct & indirect) and intangible flood damage with examples	2019 (Q8c, 4m), 2022 (Q7c, 10m)
p. 12–18	Economical evaluation of flood mitigation projects: 5 approaches (Cost/Benefit, Fixed Cost, Cost Effective, Multi-objective, Non-economic)	2023 (Q5b, 10m), 2024 (Q7c, 10m)
p. 14, 19–20	Math: Recommend optimal design river stage for a levee from flood stage, damage, return period, and project cost data	2019 (Q7c, 10m)

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4. Near-Verbatim Recurring Questions

These questions have been repeated nearly word-for-word across multiple exams:

1. Flood Proofing Strategy Considerations (SB: Lec 7 p. 13–20)
   • 2021 (Q6b), 2023 (Q6b), 2024 (Q5a), 2025 (Q6c): "Briefly explain the considerations for developing a flood proofing strategy."
2. Short Notes on Hydraulic Structures (SB: Lec 3 p. 27–28, 35–36; SB: Lec 4 p. 21; SB: Lec 7 p. 36–38)
   • 2024 (Q6a) & 2025 (Q5a): "Write short notes on: (i) Flood wall and Levee, (ii) Gravity dam, (iii) Diversion dam."
3. Flood Forecasting Definition & Role (SB: Lec 10 p. 6, 8)
   • 2023 (Q5c), 2024 (Q7b), 2025 (Q6b): "Define flood forecasting. Explain the role of flood forecasting in flood management."
4. Factors Responsible for Floods in Bangladesh (SB: Lec 1 p. 25–41)
   • 2023 (Q5a), 2024 (Q5b), 2025 (Q6a): "Explain the Geographical and Hydro-Meteorological factors responsible for floods in Bangladesh."
5. Short-Term & Long-Term Flood Management Measures (SB: Lec 3 p. 9–11)
   • 2021 (Q5a), 2024 (Q6c), 2025 (Q7b): "Illustrate the short-term and long-term measures for flood management."
6. Economic Evaluation of Flood Mitigation Projects (SB: Lec 11 p. 12–18)
   • 2023 (Q5b), 2024 (Q7c): "Briefly explain different approaches for economical evaluation of flood mitigation projects."
7. Capacity-Dependent Bed Load vs Supply-Dependent Suspended Load (SA: Lec 4 p. 9–12, 20; SA: Lec 7 p. 13)
   • 2021 (Q1c), 2022 (Q2c): "Explain with a figure why bed load is generally 'capacity dependent' and suspended load is 'supply dependent'."
8. Critical Shear Stress Proportionality for Coarse Sediment (SA: Lec 5 p. 12–13, 19–20)
   • 2021 (Q3b), 2024 (Q2b): "Prove that the critical shear stress / force required to erode coarse-grained sediment is a function of only sediment diameter."
9. Contraction Scour Insignificance (SA: Lec 9 p. 4–7)
   • 2021 (Q1b), 2022 (Q3c), 2023 (Q4c): "What is contraction scour and why is it generally not significant at a bridge site?"
10. Active vs Passive River Training Structures (SA: Lec 11 p. 1, 3–6)
    • 2022 (Q6d), 2023 (Q8a): "Explain with examples the differences between active and passive river training structures."