A Quaternary Volcanic Aquifer System in Central America: Key Factors in Groundwater Potential and Protection
In Central America, Quaternary volcanic aquifer systems play an important, and sometimes vital, role in public water-supply. For example, in Guatemala City, Managua, San Salvador, and San José de CostaRica, high-yielding wellfields have been developed and/or major spring discharges directly or indirectly captured.
Over the past 15 years the Quaternary andesitic volcanic aquifer complex on the northern side of the Valle Central in Costa Rica has been rapidly exploited to provide groundwater supplies in excess of 250 Ml/d and scientifically investigated to identify its hydrogeological characteristics. It is now believed to be one of the best understood volcanic aquifer systems of the circumPacific. Interbedded lavas and pyroclasts combine to produce a multiaquifer system of very high transmissivity and major groundwater storage. Pyroclastic tuffs have extremely high porosity coupled with moderate permeability, permitting steady recharge to deeper lava aquifers by downward leakage. Perched water-tables are widely developed above aquitards formed by massive ignimbrites. The heavy rainfall of the area generates large groundwater resources but aquifer recharge and flow mechanisms are complex, and resultant problems in the evaluation of groundwater potential and protection requirements are highlighted.
KeywordsPermeability Porosity Depression Sewage Bicarbonate
Unable to display preview. Download preview PDF.
- BG S-SEN ARA, 1985, Hydrogeological map of the Valle Central of Costa Rica.Google Scholar
- Circinn-Pacific Council for Energy and Mineral Resources, 1984, Mineral resource map of circum-Pacific region: Tulsa, AAPG.Google Scholar
- Darling, W. G., J. M. Parker, H. V. Rodriguez-Estrada, and A. J. Laudres, 1987, Investigations of a volcanic aquifer system in Costa Rica using environmental isotopes, in Proceedings, IAEA seminar “Application of isotope techniques in hydrology in Latin America,” Mexico City, September, in press.Google Scholar
- McDonald, M. G., and A. W. Harbaugh, 1983, A modular three-dimensional finite-difference ground water-water flow model ( MODFLOW ): U.S. Geological Survey Open-File Report 83875.Google Scholar
- Takasaki, K. J., G. T. Hirashiina, and E. R. Lubke, 1969, Water resources of windward Oahu, Hawaii: U.S. Geological Survey Water-Supply Paper 1894, 119 p.Google Scholar
- Weyl, R., 1980, Geology of Central America: Stuttgart,Berlin, 371 p.Google Scholar