Estudio hidrogeológico conceptual como base para determinar la influencia de la actividad minera a cielo abierto, en la dinámica de los nacimientos de agua presentes en la cuenca de la Quebrada Aguas Calientes, en la Vereda Mochuelo Bajo, Localidad de Ciudad Bolívar (Bogotá D.C. – Colombia)

Abstract

Some rural communities are immersed in conflicts due to the use of natural resources, especially non-renewable ones, currently in the town of Ciudad Bolívar, Vereda Mochuelo Bajo, there is the El Mochuelo Industrial Mining Park which exploits clays, sand and other construction materials, The progress of these mining activities could affect other resources that are vital for the communities that live in this area, such as water, therefore this study is aimed at determining whether current and future mining activities will put births and bodies of surface water that not only supply the community aqueduct but also maintain a fragile balance with the ecosystems present in this area. The hydrogeological characterization study of the Quebrada Aguas Calientes was carried out with the objective of evaluating the dynamics of groundwater in the area, based on the analysis and geological-geophysical, hydraulic and hydrogeochemical characterizations carried out in the study area. The geological-geophysical characterization concludes that the study area is lithologically conformed by a sequence of Cretaceous rocks (Arenisca Dura (Ksgd) Formation, Pleaneras (Ksgp) Formation and Labor y Tierna (Ksgt) Formation belonging to the Guadalupe Group (Kgg) ), which are plastically deformed forming an anticline structure, this structure presents a North-West course in which it is observed, from information collected in the field that is currently eroded (the Labor and Tierna (Ksgt) Formation was not found in the study area) as a consequence of erosive processes associated with glacial masses, which is why nowadays deposits defined as glacial colluvium in nature are observed in a dominant way throughout the study area.

The hydrochemical characterization indicated that the waters in this sector are of the Bicarbonate - Sodium type, where the most abundant ions in solution are the Bicarbonate ions followed by the Sodium - Magnesium ions, the hardness of the water indicates that they are very sweet waters and based on the amount of chlorides and sulphides present in these samples, it is concluded that these waters are of short transit and a direct recharge of precipitation water. The hydrogeological characterization identifies aquifer units associated with geological units of rock and deposits, the first is associated with the moderately fractured zone of the Arenisca Dura (Ksgd) and Plaeners (Ksgp) formations, for which the porous medium is associated with fracturing presenting a moderate hydrogeological importance. The deposits classified as aquifers present primary porosity in a granular medium for which the Coluvio-glacial (Qcog) Deposits and Alluvial (Qal) Deposits are related. The water cycle is a reflection of the interaction between surface and groundwater as well as its relationship with the defined hydrogeological units, configuring a fragile equilibrium, where the present deposits classified as surface aquiferous units, represent porous media by which subsurface flows and Underground feeds water sources, as well as serving as a medium where recharge is transferred to aquifer units in rock where there are moderately fractured horizons, associated with Hard Sandstone (Ksgd) Formation and Plaeners (Ksgp) Formation. The structural arrangement associated with an eroded anticline with a NW-SE preferential course, constitutes the dominant hydraulic factor in relation to groundwater flows, being the dip of each flank that determines the direction of groundwater flow. Currently mining activity It is located on the north-east flank of the anticline structure, which results in preferential flows in the opposite direction to the location of the springs located on the west flank, resulting in a hydraulic disconnection between the groundwater systems present in the rocky materials and the water sources reported along the Aguas Calientes stream. A different behavior is observed at the level of subsurface water flows that are predominantly related to the colluvial-alluvial deposits, since they do not represent groundwater, they are not governed by the same behavior associated with the anticline structure, the gradient being dominant for their flow direction associated with the topography, which indicates that these subsurface water systems may be affected by eliminating the surface layer present in the areas subject to current mining progress, which could affect the recharge of the springs present in the study area. This means that the subsurface waters that emerge are directly related to areas with infiltration power such as forests, scrub areas, grasslands and crops, therefore, as mining progresses, the infiltration area supplied by these sources will be reduced and therefore cause and effect available flows will decrease and could be lost. Therefore, the results of this hydrogeological study become valuable since they form the basis for the recovery of this degraded area and draw a clear route for ecological rehabilitation where the recharge, transit and discharge areas of surface flows are protected and underground, soils are recovered and natural cycles reestablished, the water supply is conserved and improved and a large carbon sink is created that helps mitigate the effects of climate change and global warming. This study seeks to develop a conceptual hydrogeological characterization that contributes as a territorial planning tool and as a basis for making decisions that guarantee the permanence and sustainability of the water resource over time.