CONTRIBUCIÓN A LA HIDROGEOLOGÍA VOLCÁNICA DE GRECIA, VALLE CENTRAL OCCIDENTAL DE COSTA RICA

Abstract

This work describes the geological and hydrogeological features of the NE sector of the topographical sheet Naranjo (scale 1: 50 000) in the Central Valley of Costa Rica. This area presents some veryimportant springs with production rates between 15 and 1000 l/s. The geology is characterized by pleistocenelava flows, tuffs, ignimbrites, and recent lava flows. A tectonic structure called the Alajuela Fault, exposes thepiezometric level and originated the spring Los Chorros. The aquifers in the area are formed by fractured lavaflows and ignimbrites. The average discharge of the wells in this formation is 3 l/s. The direction of the ground-water is SW, similar to the flow of the main river in this zone. The chemical compositions of water in the springsare dominated by calcium-bicarbonate.