| | Practical Sustained Yield: The rate at which groundwater can be continuously withdrawn without lowering water levels to critical stages, exceeding recharge, or causing undesirable changes in water quality (Walton, W.C., 1970, Groundwater Resource Evaluation). If sustainability is defined as "the ability to meet the needs of the present generation without compromising the ability of future generations to meet their needs," value judgments may be required to define "meeting the needs" (Wood, W., 2001, Water Sustainability - Science or Management?, Ground Water, 39(5): 641). Similar subjective judgments may be involved in determining "unacceptable consequences." Similar to Safe Yield , and
Optimum Yield, the ISWS will no longer use this term. Instead, the ISWS elects to use the term Yield and explicity state all conditions and assumptions that stand behind the determination of it. |
