Potentiometric Surface of the Alluvial Aquifer and Hydrologic Conditions at the Río Nigua de Salinas Alluvial Fan, Salinas, Puerto Rico, July 9-11, 2002

By José M. Rodríguez


In cooperation with the


Scientific Investigations Map 2910


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A synoptic survey of the hydrologic conditions in the Río Nigua de Salinas alluvial fan was conducted from July 9 to 11, 2002, to define the spatial distribution of the potentiometric surface. The survey was part of a major study to assess the ground-water quality in the Río Nigua de Salinas alluvial aquifer. The Río Nigua de Salinas alluvial fan covers approximately 9,000 acres of the more extensive South Coastal Plain Alluvial Aquifer system and is bounded along the north by foothills of the Cordillera Central mountain chain and to the south by the Caribbean Sea. Ground-water flow occurs primarily within alluvial deposits that increase in thickness toward the coast to as much as 400 feet near the center of the study area, but is highly irregular along its east-to-west extensions (Quiñones-Aponte and others, 1997). Fresh ground water in the aquifer occurs under semi-confined conditions along the coast to a distance of as much as 2 miles inland and under unconfined conditions throughout both the alluvial deposits and underlying weathered rock at areas farther inland (Quiñones-Aponte and Gómez-Gómez, 1987). The potentiometric surface was delineated using ground-water level measurements made at existing wells. Ground-water levels measurements were made at wells that were not pumping during the survey or wells that were turned off. For the latter, a recovery period of 30 minutes was allowed for the ground-water level to achieve a near static level position. Land-surface altitude from the U.S. Geological Survey (USGS) 1:20,000 scale topographic maps (Cayey, Coamo, Central Aguirre, and Salinas) were used to refer ground-water levels to mean sea level datum.


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The citation for this report, in USGS format, is as follows:


Rodríguez, J.M., 2005, Potentiometric surface of the alluvial aquifer and hydrologic conditions at the Río Nigua de Salinas alluvial fan, Salinas, Puerto Rico, July 9-11, 2002: U.S. Geological Survey Scientific Investigations Map 2910, 1 sheet.


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