Planning Urban Growth in Ground Water Recharge Areas: Central Valley, Costa Rica |
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| Authors: | Hugo Rodriguez-Estrada Hugo A Loaiciga |
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| Institution: | Hugo Rodriguez-Estrada;is a hydrogeologist with the Department of Water Resources of the Costa Rican Institute of Water Supply and Sewage (AyA), headquartered in San Jose, Costa Rica (Department of Water Resources, Instituto Costarricense de Acueductos y Alcantarillados, San Jose, Costa Rica). His current professional interests reside in the area of ground water supply and protection of wellhead areas in the Central Valley of Costa Rica. Hugo A. Loaiciga;is a professor of hydrology in the Department of Geography and Environmental Studies Program at the University of California at Santa Barbara (Department of Geography and Environmental Studies Program, University of California, Santa Barbara, CA 93106). He holds a licensure in civil engineering from the University of Costa Rica, and an M.Sc. and a Ph.D. in hydrology and water resources from the University of California at Davis. Dr. Loaiciga is also a registered civil engineer in the state of California. His research interests include the basic principles of the hydrologic cycle at all spatial scales, the interaction of surface and ground waters, and water supply analysis in arid climates of the western United States. |
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| Abstract: | Nitrate levels in the ground water of the Central Valley of Costa Rica have increased in relation to the past. Previous studies determined that the unseweved sanitation systems in the recharge areas are the main source of nitrogen. Calculations are made in this study to estimate the maximum population density allowable without improved sewage systems in order to keep the nitrogen levels in ground water below the World Health Organization (WHO) criteria. Results were achieved employing a mass balance that involved the concentration and rate of domestic effluents and the flow rate in the aquifer, as well as an estimation of the effects caused by the agricultural activity. It was concluded that, in general terms, the population density must not exceed 45 inhabitants per hectare. Otherwise, sewage systems and treatment plants are necessary. These conclusions provide a basis for urban growth planning, which will protect ground water quality. The method used in this case should apply to similar situations. |
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