What is Groundwater?
- Groundwater is the water stored beneath the Earth’s surface in soil, sand, and rock formations (aquifers).
- It forms when rainwater, rivers, and lakes percolate into the ground.
- It is a major source of drinking water, irrigation, and industry.
📌 Fact: Groundwater accounts for 30% of Earth’s freshwater, making it the largest available freshwater source.
What is the Water Table?
- The water table is the upper level of groundwater in the soil or rock.
- It rises and falls depending on rainfall, seasons, and water usage.
📌 Example: During heavy rains, the water table rises, and during droughts, it falls.
Zones of Groundwater
1️⃣ Unsaturated Zone – Contains air and water in pores.
2️⃣ Saturation Zone – Fully filled with water.
3️⃣ Water Table – Upper boundary of the saturated zone.
4️⃣ Aquifers – Rock formations that store and transmit groundwater.
📌 Example: Indo-Gangetic Aquifer – One of the largest aquifers in the world.
Types of Aquifers
| Type | Description | Example |
|---|---|---|
| Unconfined Aquifer | Directly connected to the surface, refilled by rain | Ganga Basin |
| Confined Aquifer | Trapped between layers of rock, pressurized | Artesian wells in Rajasthan |
| Perched Aquifer | A smaller water body above the main water table | Hills & plateaus |
📌 Fact: Deep aquifers take thousands of years to recharge!
Factors Affecting Groundwater Levels
✅ Rainfall & Snowmelt – More rain = Higher water table.
✅ Soil & Rock Type – Permeable rocks (sandstone) store more water than impermeable rocks (granite).
✅ Human Usage – Overuse leads to groundwater depletion.
✅ Deforestation – Less infiltration, more runoff = low recharge.
📌 Example: Punjab & Haryana face severe groundwater depletion due to excessive irrigation.
Importance of Groundwater
✔ Drinking Water Source – India relies on groundwater for 60% of drinking water.
✔ Irrigation – Supports 40% of global agriculture.
✔ Industrial Use – Used in factories and power plants.
✔ Prevents Droughts – Acts as a natural reservoir.
✔ Maintains River Flow – Many rivers depend on groundwater discharge.
📌 Example: The Ganga River gets 50% of its flow from groundwater in summer.
Problems Related to Groundwater 🚨
❌ Overextraction – Causes groundwater depletion (e.g., Delhi, Rajasthan).
❌ Pollution – Nitrate, arsenic, fluoride contamination (e.g., Bihar, West Bengal).
❌ Land Subsidence – Ground collapses when too much water is withdrawn (e.g., Mexico City).
❌ Saltwater Intrusion – Overuse near coasts pulls seawater into aquifers (e.g., Chennai).
📌 Fact: India is the world’s largest user of groundwater.
Conservation & Management of Groundwater
✅ Rainwater Harvesting – Collects rainwater to recharge groundwater.
✅ Watershed Management – Prevents runoff and improves infiltration.
✅ Drip Irrigation – Reduces water wastage in farming.
✅ Government Policies – Atal Bhujal Yojana (2020) focuses on groundwater conservation.
📌 Example: Rajasthan’s Johad system (traditional water harvesting) revived groundwater levels.
MCQs on Groundwater and Water Table
1. What is the primary source of groundwater?
a) Ocean water
b) Rainwater infiltration
c) Volcanic activity
d) Wind erosion
Answer: b) Rainwater infiltration
2. Which type of aquifer is directly connected to the surface?
a) Confined
b) Unconfined
c) Perched
d) Artesian
Answer: b) Unconfined
3. What happens when groundwater is overextracted?
a) Water table rises
b) Land subsidence occurs
c) Soil erosion stops
d) Rivers expand
Answer: b) Land subsidence occurs
4. Which Indian state faces severe groundwater depletion?
a) Kerala
b) Punjab
c) Odisha
d) Assam
Answer: b) Punjab
5. What is the main cause of groundwater pollution in Bihar & West Bengal?
a) Fluoride
b) Arsenic
c) Lead
d) Sulfur
Answer: b) Arsenic
Short Answer Questions
1. What is groundwater?
Groundwater is the water stored beneath the Earth’s surface, found in aquifers and used for drinking, irrigation, and industry.
2. What is the water table?
The water table is the upper level of groundwater in the soil. It rises during heavy rainfall and falls during droughts.
3. What are the types of aquifers?
- Unconfined Aquifer – Open to surface water.
- Confined Aquifer – Trapped between rock layers.
- Perched Aquifer – A smaller water pocket above the main water table.
4. What are the causes of groundwater depletion?
✔ Overuse for irrigation.
✔ Rapid urbanization.
✔ Deforestation reducing infiltration.
✔ Climate change reducing recharge.
5. How can groundwater be conserved?
✔ Rainwater harvesting.
✔ Drip irrigation for farming.
✔ Reforestation to improve water absorption.
✔ Government schemes like Atal Bhujal Yojana.
Conclusion
Groundwater is a vital resource, but overuse and pollution threaten its availability. Sustainable management through conservation techniques and policies is essential for future generations.
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