| Popis: |
The correct identification of recharge zones and understanding of groundwater flow through fractured and karstic media are some of the main issues in hydrogeology and are of utmost importance for managing groundwater resources. The Aburra Valley is an excellent example of a promising aquifer system for future water supply in Colombia, with recharge zones and hydrogeological units (HGU) still not well understood. One of those HGUs, the Medellin Dunite, is an ultramafic igneous rock with significant secondary porosity due to the high grade of fracturing and the presence of a pseudokarst system formed by the dissolution of magnesium-rich minerals. In this study, we aimed for the first approximation of this unit's hydrogeologic characteristics by performing a hydro-structural analysis based on a systematic collection of structural data in rock outcrops and secondary information available on karstic landforms. In order to improve the understanding of the relations between the analyzed HGU and the other units in the Aburra Valley, the main objective of our investigation was to calculate the hydraulic weight of discontinuities and determine the associated preferential groundwater flow directions. The results showed that the predominant directions of groundwater flow are WNW and ENE, which imply that lateral flows from the Dunite not only recharge the alluvial aquifers of the Aburra Valley Aquifer System (AVAS) but could also be recharging the San Nicolas Valley Aquifer System (SNVAS), another region with high rates of population growth. However, detailed studies are needed to establish the connections of the Dunite with the Medellin Amphibolite and other hard rocks of the SNVAS. Our findings show the importance of studying the Medellin Dunite and implementing management and protection measures for this aquifer unit. |
Full Text from ScienceDirect