--- title: "Bell's guide bund plan, sections, design steps" subject: "Irrigation and Drainage Engineering" chapter: 6 key: "semester_6/irrigation_and_drainage_engineering:bells-bund-plan-design-steps" source: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/bells-bund-plan-design-steps site: BCT Engineering --- # Bell's guide bund plan, sections, design steps Irrigation and Drainage Engineering · Chapter 6: River Training Works - Asked in: 2079 Asoj, 3+5 marks - Video: [Design Steps Of Guide Bank|Bell Bund|Design Criteria|Vertical Type Fall|Drop Fall |Design Canal](https://www.youtube.com/watch?v=SYP5-ccYG6E) — DIPAK MANDAL - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/bells-bund-plan-design-steps - Whole chapter: https://www.bctengineer.com/md/semester_6/irrigation_and_drainage_engineering/chapter-6 ## Question Draw a neat plan and sections of a Bell's Bund and give salient steps of its design procedure. ## Short answer Bell’s bund is a guide embankment with curved heads to give axial flow. Design steps: compute waterway W=4.75 sqrt(Q), silt factor f=1.76 sqrt(d); upstream shank 1–1.5W, tail 0.2–0.5W; curved head radius 0.5W, sweep 120–145°; top level HFL+1.5 m, width 6 m; pitching t=0.06 Q^(1/3); scour R=0.47(Q/f)^(1/3); apron width 1.5D', launched thickness 1.5t. ## Answer A **Bell's bund** is a guide bund (guide bank) on the pattern recommended by Bell, in which a pair of embankments, with curved heads upstream and short tails downstream, is laid symmetrically about the axis of a bridge or barrage so that the river approaches the waterway axially. The waterway is based on Lacey's regime width. #### Plan and sections (3 marks) ```text U/S D/S ______________________________ | ____ / upstream shank 1.0-1.5 W \ | / \ tail ( curved head, R = 0.5W, )=|=( ) 0.25 W \ sweep 120 deg / | \____/ \_____________________________/ | waterway W (Lacey) axis of bridge ``` ```text Section at shank Section at nose __6 m__ __6 m__ / \ HFL+1.5 / \ HFL/_________\ 2:1 HFL/__________\ 3:1 / pitching t \ / pitching t \ /___ apron ____\ (1.5R) /____ apron (2R) ___\ ``` #### Design steps (5 marks) 1. Design discharge $Q$, HFL, bed level and median grain size $d$. 2. Silt factor $f = 1.76\sqrt{d_{mm}}$, and waterway $W = 4.75\sqrt{Q}$. 3. Length of upstream shank $1.0$ to $1.5W$, downstream tail $0.2$ to $0.5W$. 4. Radius of upstream curved head about $0.5W$ with sweep $120$ to $145^\circ$; tail with a smaller radius, sweep about $45^\circ$. 5. Top level $=$ HFL $+ 1.5$ m, top width 6 m, side slopes 2:1. 6. Pitching thickness $t = 0.06Q^{1/3}$. 7. Scour depth $R = 0.47(Q/f)^{1/3}$; max scour below HFL: $2R$ at nose, $1.5R$ at shank. 8. Launching apron: depth below bed $D' = $ scour depth $-$ flood depth, width $1.5D'$, launched thickness $1.5t$. 9. Draw plan and sections. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. A Bell's bund is: A. A spur B. A guide bund with curved upstream heads and short downstream tail laid symmetrically about the bridge axis C. A levee far from the river D. A type of weir Answer: B. It makes the river approach the waterway axially; the waterway is based on Lacey's regime width. (Key point: What is Bell's bund) 2. Which proportions suit the Bell's bund plan? A. Tail longer than shank B. Sweep 10 degrees both ends C. Upstream shank 1-1.5W, head radius about 0.5W with sweep 120-145 degrees, tail 0.2-0.5W with about 45 degrees sweep D. Shank 0.1W Answer: C. The upstream curved head is large, the downstream tail short with smaller radius. (Key point: Head and tail) 3. Top level, width and slopes? A. HFL + 10 m, 30 m B. Bed level C. HFL + 1.5 m, 6 m, 2:1 D. HFL, 1 m, 1:1 Answer: C. Free-board of 1.5 m protects against overtopping. (Key point: Top level) 4. Maximum scour below HFL and apron design? A. R everywhere B. 2R at nose, 1.5R at shank; D' = scour - flood depth, width 1.5D', launched thickness 1.5t C. Apron width D'/2 D. 3R at shank Answer: B. R = 0.47 (Q/f)^(1/3), and the apron is designed to launch on a 2:1 slope. 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