97 percent of the water on the Earth is salt water and only three percent is fresh water; slightly over two-thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen fresh water is found mainly as groundwater, with only a small fraction present above ground or in the air.
India is endowed with a rich and vast diversity of natural resources, water being one of them. Its development and management play a vital role in agriculture production. Integrated water management is vital for poverty reduction, environmental sustenance, and sustainable economic development.
Fresh water on the earth is a renewable resource, yet the world’s supply of groundwater is steadily decreasing, with depletion occurring most prominently in Asia and North America, although it is still unclear how much natural renewal balances this usage, and whether ecosystems are threatened. The framework for allocating water resources to water users (where such a framework exists) is known as water rights.
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Surface water on the earth is water in a river, lake or fresh water wetland. Surface water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, and sub-surface seepage.
Brazil is the country estimated to have the largest supply of fresh water in the world, followed by Russia and Canada.
It is estimated that 70% of worldwide water on the earth use is for irrigation, with 15-35% of irrigation withdrawals being unsustainable. It takes around 2,000 – 3,000 liters of water to produce enough food to satisfy one person’s daily dietary need.
It is estimated that 22% of worldwide water on the earth is used in industry. Major industrial users include hydroelectric dams, thermoelectric power plants, which use water for cooling, ore and oil refineries, which use water in chemical processes, and manufacturing plants, which use water as a solvent.
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It is estimated that 8% of worldwide water on the earth use is for household purposes. These include drinking water, bathing, cooking, sanitation, and gardening.
Environmental water on the earth usage includes watering of natural or artificial wetlands, artificial lakes intended to create wildlife habitat, fish ladders, and water releases from reservoirs timed to help fish spawn, or to restore more natural flow regimes.
Water pollution is one of the main concerns of the world today. Many pollutants threaten water supplies, but the most widespread, especially in developing countries, is the discharge of raw sewage into natural waters; this method of sewage disposal is the most common method in underdeveloped countries, but also is prevalent in quasi-developed countries such as China, India, Nepal, and Iran. Sewage, sludge, garbage, and even toxic pollutants are all dumped into the water on the earth.