11.5 Paradox of Safe Yield
Safe yield was originally defined as the amount of water that could be developed from a ground water reservoir without depletion of its reserves. Over time the definition has changed as economics, protection of ground water, and environmental affects have been considered in this concept as well. So, safe yield is now defined as the amount of naturally occurring ground water that can be taken from an aquifer on a regular basis, economically and legally, without affecting the native ground water quality or forming an unwanted effect such as environmental damage. When pumping water from a ground water supply, there are many possible adverse environmental effects. By lowering stream flow it can lower lake levels or dry up wetlands. It can also then have a negative effect on infrastructures; as it can lower the land surface and cause cracking in the land surface, damaging pipes, buildings, highways, dams and more. There are many other adverse effects, and in broad spectrum this may include ecological, economical, social, cultural, and political effects. However, it is debatable what constitutes an undesirable effect. Specific yield also does not take into account the relationship between surface and ground water. It takes a deep and broad evaluation by experts of multiple fields to determine safe-yield values. Computer models are used for making ground water models and computing safe yield values.
Today, the concept of safe yield is still misunderstood. The important factor in determining safe yield is the amount of natural discharge that can be captured. It is important to focus on the discharge rather than the recharge when studying safe yield. Many improvements could be made in making safe yield a more specific and precise measurement. More intensive studies could help to create specific formulas for types of aquifers and use of water budgets and all surrounding data to determine a definition for the safe...
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