Water: A Precious Resource

• (a) The freshwater stored in the ground is much more than that present in the rivers and lakes of the world. (True)
• (b) Water shortage is a problem faced only by people living in rural areas. (False) (Urban areas also face it).
• (c) Water from rivers is the only source for irrigation in the fields. (False) (Groundwater, rain, canals are also used).
• (d) Rain is the ultimate source of water. (True).

The rainwater and water from other sources such as rivers and ponds seep through the soil and fill the empty spaces and cracks deep below the ground. The process of seeping of water into the ground is called infiltration. This refills (recharges) the groundwater.

The total water drawn by 10 tube wells for 50 houses will be very high. If the rate of drawing water is higher than the rate of recharge (by rain or other sources), the water table will go down (deplete).

1. Usage of Drip Irrigation: Delivering water directly to the base of roots drop by drop.
2. Watering plants during morning or evening to prevent evaporation loss.
3. Recycling waste water from kitchen for gardening.

1. Increasing Population: More people = more water usage for drinking, construction, etc.
2. Increasing Industries: Factories use huge amounts of water, mostly from groundwater.
3. Agricultural Activities: Farmers use pumps to draw groundwater for irrigation due to irregular rainfall.
4. Scanty Rainfall: Less rain means less recharge of groundwater.
5. Deforestation: Less trees mean less water seeps into ground.

• (a) People obtain groundwater through wells and hand pumps.
• (b) Three forms of water are solid, liquid and gas.
• (c) The water bearing layer of the earth is aquifer.
• (d) The process of water seepage into the ground is called infiltration.

(iii) Heavy rainfall

(iv) of the world remains constant.

(Ref: Textbook Figure 16.7)

• Surface
• Water Table (Top level of groundwater)
• Groundwater (Saturated zone)
• Aquifer (Underground layer of water-bearing rock)

• 71% of Earth is covered with water.
• Almost all (97%) is in seas and oceans (Saline).
• Freshwater is only about 3%. Of this, most is in glaciers/ice caps.
• Very tiny fraction (0.006%) is available for human use in rivers, lakes, groundwater.

• Water Table: Upper limit of zone where spaces between rocks are filled with water.
• Infiltration: Seeping of rainwater into soil.
• Aquifer: Water stored between layers of hard rock below water table.
• Depletion: Water table goes down if we pump out more than is replenished.

• Prevent wastage (leaking pipes).
• Rainwater Harvesting: Collecting rainwater to recharge groundwater (Water Conservation).
• Bawris: Traditional method of collecting water.
• Drip Irrigation: Efficient watering for plants using narrow tubes.
• Effect on Plants: Plants wilt and die without water (No photosynthesis, no food, no oxygen release).

• World Water Day: 22 March.
• 2003 was International Year of Freshwater.
• Suggested minimum water per person per day by UN: 50 litres (2.5 buckets).

• Water cycle maintains total water on earth, but distribution varies (scarcity).
• Water exists in 3 states: Ice (Solid), Water (Liquid), Vapour (Gas).
• Alwar district (Rajasthan): Revived dried-up rivers by constructing water harvesting structures.