Water Resources

• Water resources are sources of water that are useful or potentially useful to humans.
• Many uses of water include agricultural, industrial, household, recreational and environmental activities.
• 97% of the water on the Earth is salt water and only three percent is fresh water.

Sources of Fresh Water:

Name	Details
Surface Water	1. Surface water is water in a river, lake or fresh water wetland. 2. It is recharged through precipitation and lost through evaporation. 3. Brazil is estimated to have largest source of surface water followed by Russia and Canada.
Under River Flow	1. Besides the visible flow of water, water flowing through stones and sediments. 2. For many rivers underflow is much more in volume than visible flow.
Ground Water	1. Located in the subsurface pore space of soil and rocks. 2. Due to slow rate of turnover, it is in much larger volume and can be used for a long time without problem.
Frozen Water	1. Several schemes have been proposed to make use of icebergs as a water source. 2. Glacier runoff is considered to be surface water. 3. The Himalayas “The Roof of World”, has greatest area of glaciers.Ten of Asia’s largest rivers flow from there.
Desalination	1. Artificial process to convert saline water into fresh water. 2. Processes used are Distillation and Reverse Osmosis. 3. Expensive than other sources of fresh water.

Uses of Water:

Name	Details
Agriculture	1. It is estimated that 70% of worldwide water is used for irrigation, with 15 – 35% of irrigation withdrawals being unsustainable. 2. It takes around 2,000 – 3,000 litres of water to produce enough food to satisfy one person’s daily dietary need.
Industries	1. It is estimated that 22% of worldwide water is used in industry. 2. Manufacturing plants use water as a solvent. 3. Other industries like hydroelectric dams, thermoelectric power plants use water for cooling.
Domestic Needs	1. It is estimated that 8% of worldwide water use is for domestic purposes. 2. These include drinking water, bathing, cooking, toilet flushing, cleaning, laundry and gardening.
Environment	1. Environmental water usage includes watering of natural or artificial wetlands, artificial lakes intended to create wildlife habitat, fish ladders.

Water Stress:

Measures for water conservation:

• Use a broom instead of a hose to sweep sidewalks and driveways.
• Install a low-flow showerhead.
• When washing the car, use a hose with an on/ off nozzle or use buckets of rinse water.
• Limit shower time to 5 minutes or less.

Prevention of water pollution:

• Be careful about what you throw down your sink or toilet. Don’t throw paints, oils or other forms of litter down the drain.
• Take great care not to overuse pesticides and fertilizers. This will prevent runoffs of the material into nearby water sources.
• By having more plants in your garden you are preventing fertilizer, pesticides and contaminated water from running off into nearby water sources.
• Don’t throw litter into rivers, lakes or oceans. Help clean up any litter you see on beaches or in rivers and lakes, make sure it is safe to collect the litter and put it in a nearby dustbin.