--- title: "Gully control and land stabilisation" subject: "Transportation Engineering I" chapter: 5 key: "semester_6/transportation_engineering_i:gully-control" source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/gully-control site: BCT Engineering --- # Gully control and land stabilisation Transportation Engineering I · Chapter 5: Hill Roads - Asked in: 2079 Jestha, 6 marks; 2072 Magh (asked 2 times) - Video: [Erosion Control Structure: One Rock Dam](https://www.youtube.com/watch?v=qvrp6qRvYbo) — Quivira Coalition - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/gully-control - Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-5 ## Question What is gully control and land stabilization? Explain any four gully control structures/methods used in hill roads. ## Short answer Gully control stops gully growth by reducing flow velocity and trapping sediment; land stabilization uses structures and vegetation to secure slopes. Methods include check dams, drop structures, diversion drains, and bio-engineering measures like planting grass and shrubs. ## Answer #### Gully control and land stabilisation A **gully** is a deep channel cut by concentrated surface flow on a slope. **Gully control** means stopping the growth of such channels and filling them, by reducing the flow velocity and trapping sediment. **Land stabilisation** means making the unstable slope or gully bank stable by engineering structures and vegetation (bio-engineering) so that erosion and landslides do not continue and endanger the road. #### Gully control structures / methods (any four) 1. **Check dams (gabion, stone masonry or brushwood)** - small cross-barriers placed in the gully at intervals so that the toe of the upper dam is at the same level as the crest of the next lower dam. They reduce the bed slope, slow the flow, and trap sediment. 2. **Drop structures / chutes** - masonry or concrete stepped channels that lead the flow safely down a steep gully; energy is dissipated in stilling pools. 3. **Diversion drains and catch drains** - intercept and divert the runoff from the gully head, reducing the discharge entering it. 4. **Vegetative and bio-engineering measures** - planting grass (vetiver, napier), shrubs and trees on gully banks and bed; brush layering, live check dams, fascines and jute/coir netting hold the soil and bind the slope. 5. **Gabion walls and re-grading of gully sides** - regrade steep banks to a stable slope (1:1.5 to 1:2) and protect the toe. ```text upper ___ flow -> | \__ check dam 1 \ \___ \ silt check dam 2 toe of dam 1 level with crest of dam 2 ``` These works are used with proper drainage so that the road is not damaged by gully extension. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What does gully control aim to do? A. Encourage gullies to deepen B. Stop gully growth and fill them by reducing flow velocity and trapping sediment C. Increase flow velocity D. Remove all vegetation Answer: B. Controlling velocity and trapping sediment stops the channel growing. (Key point: Gully control meaning) 2. How are check dams spaced in a gully? A. Randomly B. The toe of the upper dam is at the same level as the crest of the next lower dam C. All at the same level at the top D. Only one at the mouth Answer: B. This arrangement reduces the bed slope between dams and traps sediment. (Key point: Check dam spacing) 3. How do vegetative measures help in gully control? A. Plants such as vetiver and napier grass, brush layering, fascines and jute net hold and bind the soil B. They loosen the soil C. They increase runoff D. They have no effect Answer: A. Roots and netting bind the soil and slow the flow. (Key point: Bio-engineering) 4. What is the role of diversion and catch drains in gully control? A. They carry more water into the gully B. They block the road C. They store sediment D. They intercept runoff from the gully head, reducing discharge entering it Answer: D. Less discharge into the gully reduces its erosive growth. (Key point: Diversion drains) ## Related in Transportation Engineering I - [Special structures in hill roads](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahill-special-structures) — Transportation Engineering I, chapter 5 - [Hill road drainage structures](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahill-drainage-structures) — Transportation Engineering I, chapter 5, asked 4× - [Design and construction problems of hill roads](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahill-problems) — Transportation Engineering I, chapter 5, asked 11× - [Typical cross-sections of hill roads](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahill-cross-sections) — Transportation Engineering I, chapter 5, asked 9× - [Surface water drainage in hill roads](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahill-surface-drainage) — Transportation Engineering I, chapter 5, asked 2× - [Catch water drains in hill roads](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Acatch-water-drain-hill) — Transportation Engineering I, chapter 5, asked 2× ## Related in other subjects - [Road maintenance; gully control measures](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Aroad-maintenance-gully-control) — Transportation Engineering II, chapter 4 - [Why temporary structures are used](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Awhy-temp-structures) — Building Technology, chapter 8 - [Four quadrant operation in DC motor control](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Afour-quadrant-dc-motor-control) — Utilization of Electrical Energy, chapter 3 - [Static Ward-Leonard four quadrant control](https://www.bctengineer.com/question.md?key=semester_7%2Futilization_of_electrical_energy%3Astatic-ward-leonard-four-quadrant) — Utilization of Electrical Energy, chapter 3