Science · Class 7
Water: A Precious Resource
Groundwater, water management, and drought.
4 sections15–25 min read6 MCQs · 2 examples
Chapter Overview
Only a small fraction of Earth's water is freshwater. This chapter covers groundwater, aquifers, depletion, water management, drip irrigation, and rainwater harvesting.
Water Distribution
- 97% ocean (salty); 2% glaciers; ~1% freshwater
- Groundwater in aquifers between rocks
- Water table: upper level of saturated zone
Water Scarcity
- Overuse, pollution, deforestation lower water table
- Unequal distribution — Rajasthan vs Kerala
- Drought: prolonged shortage
Conservation
- Rainwater harvesting: rooftop collection to tanks/recharge pits
- Drip irrigation saves water in agriculture
- Reduce wastage; recycle grey water where possible
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Groundwater
How is groundwater recharged?
- 1Rainwater percolates through soil
- 2Recharge pits and check dams help
- 3Forests increase infiltration
Answer
Percolation of rainwater
Drip irrigation
Why is drip irrigation better than flood irrigation?
- 1Water drips directly to roots
- 2Less evaporation and runoff
- 3Saves 30–50% water
Answer
Targeted delivery reduces waste
Key Points to Remember
- ✓ Bawri (stepwells) traditional harvesting in Rajasthan
- ✓ Fluorosis from excess fluoride in groundwater
- ✓ Water is universal solvent
Exam Tips
- • Draw water cycle including groundwater
- • Explain rainwater harvesting at home
- • List causes of water scarcity
Practice MCQs — Water: A Precious Resource
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 6Score: 0/0
Most Earth's water is: