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Non-saline surface water is replenished by precipitation and by recruitment from ground-water. It is lost through evaporation, seepage into the ground where it becomes ground-water, used by plants for transpiration, abstracted by mankind for agriculture, living, industry etc. or discharged to the sea where it becomes saline.
Classification of non-saline surface water quality
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The field of hydrometry classifies fresh surface water quality intended for human use into five categories:
- Class 1 is extra-clean fresh surface water resource used for conservation, not necessarily required to pass through a water treatment process, and requiring only an ordinary process for pathogenic destruction and ecosystem conservation where basic organisms can breed naturally.
- Class 2 is very clean fresh surface water resource used for consumption, which requires an ordinary water treatment process before use, for aquatic organism of conservation, fisheries, and recreation.
- Class 3 is medium-clean fresh surface water resource used for consumption, which requires passing through an ordinary treatment process before use for agriculture.
- Class 4 is fairly clean fresh surface water resource used for consumption, but requires a special water treatment process before use for industry.
- Class 5 is the source which is not classified in class 1-4 and only suitable for navigation use.
Conjunctive use of ground and surface water
Surface and ground water are two separate entities, so they must be regarded as such. However, there is an ever-increasing need for management of the two as they are part of an interrelated system that is paramount when the demand for water exceeds the available supply (Fetter 464). Depletion of surface and ground water sources for public consumption (including industrial, commercial, and residential) is caused by over-pumping. Aquifers near river systems that are over-pumped have been known to deplete surface water sources as well. Research supporting this has been found in numerous water budgets for a multitude of cities.
Response times for an aquifer are long (Young & Bredehoeft 1972). However, a total ban on ground water usage during water recessions would allow surface water to better retain levels required for sustainable aquatic life. By reducing ground water pumping, the surface water supplies will be able to maintain their levels, as they recharge from direct precipitation, runoff, etc.
- Articles linking to this page
- Environmental Persistent Pharmaceutical Pollutant EPPP
- Optimum water content for tillage
- Applied Hydrogeology, Fourth Edition by C.W. Fetter.
- R.A. Young and J.D. Bredehoeft Digital simulation for solving management problems with conjunctive groundwater and surface water systems from Water Resources Research 8:533-56
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