CHAPTER - 15 WATER

1) World water day :- The year 2003 was observed as the INTERNATIONAL YEAR OF FRESHWATER to make people aware of this dwindling natural resource. 22 MARCH is celebrated as the WORLD WATER DAY.

2) Water on the earth’s surface :- About 71 % of the earth’s surface is covered with water. Water is present in the oceans, seas, rivers, lakes, ice caps, as ground water and in the atmosphere. Most of this water is not fit for human consumption. The water that is fit for human use is freshwater.

3) Water cycle :- WATER CYCLE The water from the oceans and surface of the earth evaporates and rises up in the air. It cools and condenses to form clouds and then falls back to the earth as rain, snow or hail. This circulation of water between the oceans and land is called water cycle. In the water cycle, water is found in three different forms as solid, liquid and gas. The solid forms of water are ice, and snow is found as ice caps at the poles and snow covered mountains and glaciers. The liquid form of water is found in oceans, lakes, rivers and as underground water. The gaseous form of water is found as water vapour in the air around us. WATER CYCLE

Water cycle

4) Groundwater :- Water is present underground as groundwater. The upper layer of the groundwater is called the water table. The water table may be at a depth of one metre or at a depth of several metres below the ground. The water from rain, rivers, lakes and ponds seeps through the soil and fills the space below the ground. The process of seeping of water through the soil is called infiltration. At some places groundwater is stored between layers of hard rock. This is called aquifier. Water from aquifiers is pumped and taken out through hand pumps and tube wells.

5) Depletion of water table :- If we draw more water from the ground than the amount of water which seeps into the ground, then the water table goes down and gets depleted. Water table gets depleted due to :- i) Increase in population ii) Industrial activities iii) Agricultural activities iv) Decrease in rainfall v) Deforestation

6) Distribution of water :- - The distribution of water is not the same at all places on the earth. - Some places have more rain and are rich in water and some places like deserts have less rainfall. - Excess rain cause floods and lack of rain causes drought. Drought Flood

7) Water management :- Water management is preventing wastage of water, using water carefully and recharging ground water. Water management can be done by :- i) Repairing leaking pipes and taps. ii) Not wasting water during brushing teeth, shaving, bathing, washing clothes and during other activities. iii) Rainwater harvesting. iv) By drip irrigation of plants. Drip irrigation :- is a method of watering plants using narrow pipes through which water drips into the base of the plants.

Rainwater harvesting