use a resource in the future. Option value is often considered "closest" of the preservation values to use values.

overdrafting—

ground water supply that is being used in excess of its natural recharge rate.


potentiometric surface—

represents the height of rise of the water due to hydrostatic pressure when the constraint of the confining layer is removed (see Figure 2.2). Sometimes referred to as the piezometric surface.

present value—

the value of a time-dependent benefit or cost obtained by discounting the values back through time to the present.


rate of time preference—

rate of conversion of value between time periods. It is defined at the individual level; it is a feature of peoples' desires.

recharge—

the replenishment of water beneath the earth's surface, usually through percolation through soils or connection to surface water.

recreational value—

one of the use values provided by water. It is rooted indirectly to the value of ground water, which plays a role in providing surface water.

regulatory impact analysis (RIA)—

a required analysis to be performed to determine the benefits and costs of a proposed regulation.

renovated ground water—

ground water from which certain contaminants have been removed, synonymous with remediated ground water.

reverse osmosis—

is a highly efficient removal process for inorganic ions, salts, some organic compounds, and in some designs, microbiological contaminants. Reverse osmosis resembles the membrane filtration process in that it involves the application of a high feed water pressure to force water through semipermeable membrane. In osmotic processes, water spontaneously passes through semipermeable membrane from a dilute solution to a concentrated solution in order to equilibrate concentrations. Reverse osmosis is produced by exerting enough pressure on a concentrated solution to reverse this flow and push the water from the concentrated solution to the more dilute one. The result is clear permeate water and a brackish reject concentrate (NRC, 1997).

riparian—

associated with stream banks.


service flows—

indirect and direct benefits to consumers attributable to a provision of services over time.


total economic value (TEV)—

the sum of the extractive and in situ values. From the perspective of how to calculate the total economic value, it is the sum of use and nonuse values.

travel cost method—

an indirect valuation method that values a recreation site by estimating the demand for access to the site; expenditures on the travel required to reach a recreational site are interpreted as a measure of willingness to pay for the recreational experience (Young, 1996).


unconfined aquifer—

see confined aquifer.

use value—

determined by a resource's or environmental asset's contribution to



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