---
title: "Water logging: causes, effects, remedies"
subject: "Irrigation and Drainage Engineering"
chapter: 9
key: "semester_6/irrigation_and_drainage_engineering:water-logging-causes-effects-remedies"
source: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/water-logging-causes-effects-remedies
site: BCT Engineering
---

# Water logging: causes, effects, remedies

Irrigation and Drainage Engineering · Chapter 9: Water Logging and Drainage

- Asked in: 2079 Asoj, 4 marks; 2078 Chaitra, 6 marks; 2080 Chaitra, 4 marks; 2074 Bhadra, 4 marks; 2073 Bhadra, 3 marks; 2068 Chaitra (old course), 1+2+2+3 marks; 2065 Shrawan (old course), 6 marks; 2063 Asoj (old course), 8 marks; 2075 Baisakh, 6 marks; 2070 Chaitra (old course), 6 marks; 2064 Jestha (old course), 6 marks; 2071 Bhadra, 4 marks; 2062 Baisakh (old course), 4+4 marks (asked 13 times)
- Video: [Water Logging | Causes | Effects | How to Prevent water logging| Irrigation Engineering| Shiwani Jha](https://www.youtube.com/watch?v=spKGq-__0H8) — Shiwani Jha
- 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/water-logging-causes-effects-remedies
- Whole chapter: https://www.bctengineer.com/md/semester_6/irrigation_and_drainage_engineering/chapter-9

## Question

What is water logging? Write down the principal causes, effects and preventive (remedial / reclamation) measures of water logging in canal irrigated agricultural land.

## Short answer

Water logging is saturation of the root zone when the water table is within about 1.5 m of the ground surface. Causes: seepage from unlined canals, over-irrigation, poor drainage, and impervious subsoil. Effects: reduced crop yield, soil salinity, and health hazards. Prevention/remedies: canal lining, controlled irrigation, and surface/sub-surface drains.

## Answer

**Water logging** is the condition in which the water table rises so close to the ground surface that the root zone of crops is saturated: the soil pores are filled with water, so air cannot enter. A field is generally said to be waterlogged when the water table is within about 1.5 m of the ground surface, so that the capillary fringe reaches the root zone.

#### Causes
1. **Seepage from unlined canals and distributaries**, which recharges the groundwater continuously.
2. **Over-irrigation** and wasteful application of water by farmers, causing deep percolation beyond the crop need.
3. **Inadequate natural drainage:** flat topography, as in the Terai, with no outlet for excess water.
4. **Obstruction of natural drains** by canals, roads, railways and embankments built across the drainage lines.
5. **Heavy rainfall and flooding** over an impervious or clayey subsoil.
6. **Impervious layer** at a shallow depth, which holds the percolated water.
7. **Absence or poor maintenance of drains,** and lack of canal lining.
8. **Rise of the water level in rivers/reservoirs,** which raises the groundwater in the adjacent land.

#### Effects
- **Crop yield falls:** roots lack oxygen, and nutrient uptake and the activity of soil bacteria are reduced; crops may die.
- **Salinity and alkalinity:** capillary rise brings salts to the surface, leaving white salt crusts after evaporation.
- **Soil temperature falls** and tillage becomes difficult; machines cannot work on wet soil.
- Reduced cultivable area and delayed sowing.
- **Health problems:** mosquitoes and water-borne diseases.
- Damage to the foundations of buildings and roads; loss of land value.

#### Preventive and remedial (reclamation) measures
| Group | Measures |
|---|---|
| Preventing the rise of the water table | Lining of canals and water courses; controlled intensity of irrigation; avoiding over-irrigation; efficient water management; restricting the supply to the crop need |
| Improving natural drainage | Excavation and cleaning of natural drains, providing cross-drainage works with adequate waterway, removing obstructions |
| Surface drainage | Open field, collector and main drains to carry away excess rain and irrigation water |
| Subsurface drainage | Tile or pipe drains and mole drains to lower the water table |
| Vertical drainage | Tube wells pumping groundwater, which also supply irrigation water |
| Other | Interceptor drains along the foot of the canal, crop rotation, deep-rooted crops (biological drainage), proper land levelling |

Of these, prevention (canal lining, disciplined water use) is cheaper than cure. Where the water table has already risen, a combination of surface drains with tile drains or tube wells is used for reclamation.

## Check yourself

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

1. What is water logging?
   A. Water table rises so near the surface that the root zone is saturated and air cannot enter the soil pores
   B. Standing water only on the surface after rain
   C. Lowering of the water table below the roots
   D. Excess salt deposits on the soil surface
   Answer: A. Water logging means a high water table saturating the root zone, generally within about 1.5 m of ground surface. (Key point: Definition of water logging)

2. Which is a principal cause of water logging in canal irrigated land?
   A. Deep ploughing of the field
   B. Seepage from unlined canals and over-irrigation recharging groundwater
   C. Pumping too much groundwater with tube wells
   D. Lining of the canal
   Answer: B. Seepage and wasteful irrigation continuously recharge groundwater, especially with poor natural drainage. (Key point: Causes of water logging)

3. How does water logging lead to salinity?
   A. Excess water dissolves salts and carries them deep
   B. Roots release salts into the soil
   C. Capillary rise brings salts up, which remain as crusts after evaporation
   D. Soil temperature rises and forms salts
   Answer: C. A high water table lets capillary action carry salts to the surface where evaporation leaves white crusts. (Key point: Salinity effect)

4. Which is the preferred approach and why?
   A. Reclamation by tube wells only, since prevention is costly
   B. Doing nothing until the table has risen
   C. Increasing irrigation intensity
   D. Prevention by canal lining and water discipline, as it is cheaper than cure
   Answer: D. Prevention (lining, controlled irrigation) is cheaper; surface/tile drains or tube wells are used for reclamation where the table has already risen. (Key point: Remedial measures)

## Related in Irrigation and Drainage Engineering

- [Water logging remedies and surface drainage in Terai](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Awater-logging-causes-surface-drainage-terai) — Irrigation and Drainage Engineering, chapter 9
- [Internal/external drainage; water logging; Terai surface drainage](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Ainternal-external-drainage-water-logging-terai) — Irrigation and Drainage Engineering, chapter 9
- [Necessity and methods of drainage of irrigated land](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Adrainage-necessity-methods) — Irrigation and Drainage Engineering, chapter 9, asked 3×
- [Short note: Design of drainage of irrigated land](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Adrainage-irrigated-land-design-note) — Irrigation and Drainage Engineering, chapter 9
- [Reservoir capacity with irrigated areas](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Areservoir-capacity-areas-79j) — Irrigation and Drainage Engineering, chapter 2

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