Economics ppt (1)


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Economics ppt (1)

  1. 1. WHAT IS GROUNDWATER?     Groundwater is the water found underground in the cracks and spaces in soil, sand and rock. It is stored in and moves slowly through geologic formations of soil, sand and rocks called aquifers. It is the water located beneath the earth's surface in soil pore spaces and in the fractures of rock formations. Groundwater is a highly useful and often abundant resource. Groundwater sustains rivers, wetlands and lakes, as well as subterranean ecosystems within karst or alluvial aquifers.
  2. 2.   Typically, groundwater is thought of as liquid water flowing through shallow aquifers, but technically it can also include soil, moisture, permafrost (frozen soil), immobile water in very low permeability bedrock, and deep geothermal or oil formation water. However, over-use, or overdraft, can cause major problems to human users and to the environment. The most evident problem (as far as human groundwater use is concerned) is a lowering of the water table beyond the reach of existing wells. Wells must consequently be drilled deeper to reach the groundwater; in some places (e.g., California, Texas and India) the water table has dropped hundreds of feet because of extensive well pumping  Groundwater provides the United States with half of its drinking water. It also waters 40% of American agriculture.
  3. 3.  As ageing large-scale surface irrigation schemes have become increasingly inefficient, and farmers have begun growing a wider range of crops requiring water on demand, the number of groundwater wells in India has exploded. In 1960, there were fewer than 100,000 such wells; by 2006 the figure had risen to nearly 12 million. In India, a possible solution to over-use of groundwater is emerging, known as 'groundwater recharge'. It involves capturing rainwater that would otherwise runoff, and using it to refill aquifers.  In the Punjab region of India, for example, groundwater levels have dropped 10 meters since 1979, and the rate of depletion is accelerating.
  4. 4. SUSTAINABILITY OF GROUNDWATER Experts say the connection between surface water and groundwater has been overlooked and that integration is needed to protect water supply and the ecosystem. “Unless surface water is available to recharge the aquifers, groundwater levels will decline,” said Carl Hauge, former chief hydro geologist with the Department of Water Resources (DWR). “That is, when pumping takes groundwater out of aquifers, and there is no surface water to recharge the aquifer, groundwater levels decline.” In some places, groundwater use