Estudio Hidrogeológico del acuífero de la cuenca alta del río Pita en valle norte del volcán Cotopaxi

Abstract

The Upper Pita River Basin (CAP), with an area of 200 km2, is an important multi-layered aquifer system formed in a mountainous area of the Ecuadorian paramo, developed in a complex geological environment of volcanic and Plio-Quaternary volcanic formations, and Affected by tectonics and active volcanism present in the area. Two different water units have been identified for their lithological composition and hydraulic properties of permeability (K) and transmissivity (T): Unit A with values of K = 15 m / day and T = 750 m2 / day, corresponding to fractured lavas; And Unit B with values of K = 0.3 m / day and T = 75 m2 / day that corresponds lithologically to lahars interspersed with pyroclastic flows. Unit A is characterized by being a free aquifer of short extension (only manifested in the high parts (above 4000 m), while Unit B covers the largest extension in the basin. Finally, this work determines that: (1) the recharge takes place in permeable formations between 3,600 and 4,000 masl, using stable isotopes; and (2) there is a strong tectonic and geochemical influence of a deep aquifer on the shallow groundwater chemistry of the system.