Towards the elaboration of a hydrogeological model of the Guachiría river basin (Colombia)

Abstract

In recent years, extreme climatic variations have generated obvious effects on natural resources, harming one of the most important: water. A clear example of this is the Guachiría River Basin, located in Colombia, the prolonged dry seasons of the last decade have harmed both the biota and the civilian population, since they depend mainly on this resource. The present study aims to increase the state of the art on hydrometeorological, hydraulic variables and, in general, to understand the hydrogeological conditions of the Guachiría River Basin, this with the purpose of providing information that serves as baseline for the elaboration of a conceptual hydrogeological model (CHM) that helps in decision-making by the entities in charge of water resource management. First, the morphometric and geological conditions of the area were determined, finding that there is a predominance of flat areas with little slope, made up of unconsolidated deposits, extensive flood zones and wind influence on fluvial deposits. Then, starting from a mass balance, a water balance was carried out in the basin to quantify the resource in the area; In turn, favorable recharge zones were identified in several sectors: one part towards the foothills in the area of high slopes and another towards the deposits with eolian influence, made up of sandy and sandy loam soils that overlie the Guayabo Formation. In addition, through pumping tests, different hydraulic parameters were determined, and the aquifers were classified as free, confined, and semi-confined, linked to the lithology of the area, due to their extension and lithological complexity. Finally, a hydrogeochemical sampling was carried out, where mostly relatively young waters, with little transport and high iron content were found.