Author
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Bouwer, Herman |
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Submitted to: International Conference on Water Resources Engineering Proceedings
Publication Type: Proceedings Publication Acceptance Date: 8/18/1995 Publication Date: N/A Citation: N/A Interpretive Summary: Conflicts arise where the sum of surface water rights and groundwater rights exceeds the renewable supply of water. To reduce groundwater withdrawal, courts of law have classified groundwater near streams as "subflow" or water in "underground channels" that would still be subject to surface water rights and; hence, cannot be pumped by landowners who do not have surface water rights. This paper presents an analysis concluding tha hydrologically, these classifications do not hold water. The main issues are how groundwater pumping affects stream flow, and how conflicting water uses can be resolved by regional approaches and integrated water resources management rather than by robbing Peter to Pay Paul. Beneficiaries of this research include legal and governmental entities dealing with water law, stakeholders in rulings made by those entities, and the public at large. Technical Abstract: Surface water-groundwater relations and the effect of groundwater pumping on streamflow are hydrologic issues that are not always properly understood by the nontechnical sector (legal, adjudication, regulatory, etc.). The main issue is how groundwater pumping affects stream flow. Generally, a lowering of groundwater levels will decrease streamflow where groundwater levels are relatively high and groundwater flow is mostly lateral and gradient (slope of water table) controlled, but not where groundwater is already relatively deep and seepage flow is mainly downward and gravity controlled. Where channel perimeters are covered with a layer of sediment or other clogging material, the flow below the channel bottom becomes unsaturated if the groundwater level drops to about 1 m below the bottom. Further lowering of groundwater levels then will not increase seepage flows. |
