---
title: "Short note: Erosion"
subject: "Engineering Geology I"
chapter: 6
key: "semester_3/engineering_geology_i:short-note-erosion"
source: https://www.bctengineer.com/q/semester_3/engineering_geology_i/short-note-erosion
site: BCT Engineering
---

# Short note: Erosion

Engineering Geology I · Chapter 6: Physical Geology

- Asked in: 2076 Chaitra, 2 marks
- Video: [Weathering, Erosion, and Deposition Overview](https://www.youtube.com/watch?v=70y3BpmUpRc) — Patrick Haney
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/engineering_geology_i/short-note-erosion
- Whole chapter: https://www.bctengineer.com/md/semester_3/engineering_geology_i/chapter-6

## Question

Write a short note on erosion.

## Short answer

Erosion is the wearing away of the earth's surface by agents (water, glacier, wind, waves) through abrasion, hydraulic action, solution and plucking. It causes scour at bridge piers, bank cutting, gully formation and reservoir siltation; in Nepal, steep Siwalik slopes erode rapidly.

## Answer

**Erosion** is the wearing away of the earth's surface by the removal of weathered material by agents such as running water, glacier, wind, sea waves and groundwater.

- **Mechanisms:** abrasion (scraping by carried load), attrition (particles wear each other), hydraulic action (force of water), corrosion/solution (chemical dissolving), deflation (wind lifting fine particles) and plucking (glacier pulling out blocks).
- **Types:** fluvial, glacial, aeolian, marine, and groundwater erosion.
- **Factors:** rock hardness, slope, rainfall, vegetation cover and human activity.
- **Engineering effects:** scour at bridge piers, bank cutting, gully formation, siltation of reservoirs, and loss of fertile soil. In Nepal the young, steep Siwalik and Mahabharat slopes erode very fast.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Erosion is:
   A. Wearing away of the surface by removal of weathered material by agents
   B. Chemical change of minerals
   C. Compaction
   D. Melting
   Answer: A. Agents include water, ice, wind, waves. (Key point: Definition)

2. Which mechanism belongs to glaciers?
   A. Deflation
   B. Plucking
   C. Hydraulic action
   D. Corrosion
   Answer: B. Deflation is wind; hydraulic action is water. (Key point: Plucking)

3. Deflation is:
   A. Glacier pulling blocks
   B. Water force
   C. Wind lifting fine particles
   D. Chemical dissolving
   Answer: C. Wind erosion lowers the ground. (Key point: Deflation)

4. Which is an engineering effect of erosion?
   A. Increase in soil fertility
   B. Stronger foundations
   C. Less landslides
   D. Scour at bridge piers and siltation of reservoirs
   Answer: D. Also bank cutting and gully formation. (Key point: Effects)