Water Resources — Part 1: Sources, conservation and rainwater harvesting: visual lesson, ICSE Class 10 Geography (H.C.G. Paper 2)

Lesson

Water: plenty, yet scarce

Part 1 — India receives a great deal of rain, yet many towns queue for tankers in May and many villages see their wells run dry. The answer lies in where, when and how water is found and used.

In this lesson you will

Distinguish surface water from groundwater with examples
Explain why water conservation is needed in India
Describe rooftop rainwater harvesting and explain how it recharges groundwater

Table of sources of fresh water with type and example
Source	Type	Example
Rivers	Surface water	Ganga, Godavari
Lakes and tanks	Surface water	Lakes of Kashmir, tanks of Tamil Nadu
Reservoirs	Surface water	Behind dams
Groundwater	Below the surface	Wells and tube wells of the Ganga plain

Diagram

Surface water and groundwater

Surface water is water on the surface of the land: rivers, lakes, ponds, tanks and reservoirs. It is fed by rain and, in the north, by melting snow. Groundwater is water that has soaked into the ground and fills the pores and cracks of rocks below the water table, in layers called aquifers. It is drawn up through wells and tube wells and is renewed (recharged) when rain soaks in.

Concept

Where India’s water is found

Northern plains: large perennial rivers fed by Himalayan snow and monsoon rain; thick, porous alluvium stores plenty of groundwater, close to the surface. Peninsular plateau: rivers are rain-fed and shrink in the dry season; hard, impervious crystalline rocks hold little groundwater, so water is stored in tanks and reservoirs. Western Rajasthan: scanty rain, few rivers, deep and often salty groundwater. Coasts and the north-east: heavy rain, but much of it runs off quickly to the sea.

Table comparing surface water and groundwater in three regions of India
Region	Surface water	Groundwater
Northern plains	Perennial snow-fed rivers	Plentiful, shallow (porous alluvium)
Peninsular plateau	Seasonal rain-fed rivers, tanks	Limited (hard rock)
Western Rajasthan	Very scarce	Deep, often salty

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