---
title: "Significance of groundwater and potential zones"
subject: "Engineering Geology II"
chapter: 3
key: "semester_4/engineering_geology_ii:groundwater-significance-zones"
source: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/groundwater-significance-zones
site: BCT Engineering
---

# Significance of groundwater and potential zones

Engineering Geology II · Chapter 3: Hydrogeology

- Asked in: 2078 Poush
- Video: [Groundwater Hydrology-I](https://www.youtube.com/watch?v=7iBKqwwhb0Y) — Vidya-mitra
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/engineering_geology_ii/groundwater-significance-zones
- Whole chapter: https://www.bctengineer.com/md/semester_4/engineering_geology_ii/chapter-3

## Question

Write down the engineering significance of groundwater. Mention the different water potential zones of Nepal.

## Short answer

Groundwater supplies drinking and irrigation, affects foundations, slope stability, tunnels, and dams; pumping can cause subsidence. Nepal's zones: Terai – very high; Bhabar – high recharge; Siwalik – low to medium springs; intermontane basins – medium to high; middle hills – low to medium springs; high mountains – low, local.

## Answer

#### Engineering significance of groundwater
1. **Water supply** for drinking, irrigation and industry.
2. **Foundation and excavation:** high water table lowers bearing capacity and requires dewatering.
3. **Slope stability:** pore pressure reduces shear strength and triggers landslides.
4. **Tunnels:** water inflow and flooding; need drainage and grouting.
5. **Dams and reservoirs:** seepage, uplift pressure, leakage and piping.
6. **Roads:** poor drainage damages subgrade and pavement.
7. **Chemical effects:** sulphate and acidic water attack concrete and steel.
8. **Settlement:** pumping lowers water table, causing subsidence.
9. **Springs** are the main water source in the hills.

#### Water potential zones of Nepal
| Zone | Potential |
|---|---|
| Terai (alluvial plain) | Very high; shallow and deep aquifers |
| Bhabar zone | High recharge, deep water table |
| Siwalik/Churia | Low to medium, springs |
| Intermontane basins (Kathmandu, Pokhara) | Medium to high |
| Middle hills (Lesser Himalaya) | Low to medium, springs in fractured rocks |
| High mountains | Low, local in moraines and fractures |

## Check yourself

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

1. How does groundwater endanger slope stability?
   A. Pore pressure reduces shear strength and can trigger landslides
   B. It increases the friction between grains
   C. It always cements the soil and raises shear strength
   D. It only affects the colour of the soil
   Answer: A. Pore water pressure lowers effective stress and so shear strength, which triggers slides. (Key point: Groundwater and slope stability)

2. What is the effect of a high water table on a foundation?
   A. It raises bearing capacity of the soil
   B. It lowers bearing capacity and requires dewatering during excavation
   C. It has no effect on excavation
   D. It only matters for tunnels
   Answer: B. A high water table reduces bearing capacity and makes excavation difficult unless the site is dewatered. (Key point: Foundation effects)

3. Which zone of Nepal has very high groundwater potential with shallow and deep aquifers?
   A. High mountains
   B. Siwalik/Churia
   C. Terai alluvial plain
   D. Middle hills
   Answer: C. The Terai alluvial plain has thick sediments with shallow and deep aquifers; hills and mountains have low to medium potential. (Key point: Water potential zones)

4. How is the Bhabar zone characterised?
   A. Low recharge with shallow water table
   B. Springs only in moraines
   C. Medium potential in intermontane basins
   D. High recharge but a deep water table
   Answer: D. Coarse Bhabar deposits take in much recharge, but water sinks deep, so the water table is deep. (Key point: Bhabar zone)

## Related in Engineering Geology II

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