Abstract

DAVILA LUNA, Jaime; DIAZ CARAVANTES, Rolando Enrique; NAVARRO NAVARRO, Luis Alan  and  ROMEO MENDEZ, Estrella. Tailings dams in the northwestern portion of the state of Sonora: a geographical approximation through remote sensing. Invest. Geog [online]. 2018, n.97, 00008. ISSN 2448-7279.  https://doi.org/10.14350/rig.59624.

Water is a key driver of development, since the well-being of societies are entirely dependent on the use of this resource. Since the availability of freshwater in the world is often limited in quality and quantity, a sustainable and balanced harmonization of the multiple uses of water is a complex task, considering the varied and different types of social, economic, political and environmental interests that unavoidably compete with each other given the limited availability of the resource.

For its part, mining is one of the key drivers of the economy; on the one hand, it is a major job-creating activity which translates into regional economic development and, on the other, mining is highly predatory on the ecological environment in the territory where it operates, and regularly requires extensive environmental mitigation works.

Ore concentration methods are multiple, according to the mineral mined; those dealing with metallic mining often produce enormous amounts of pollutants, as they involve the use of high concentrations of catalysts diluted in large volumes of water. These require large containment structures during the ore refining stages and the final disposal of non-usable wastes, called Tailings Dams.

The challenge in the near future is to conduct this operation while ensuring environmental sustainability through Integrated Water Management, involving the coordinated management of all uses, demands by and needs of the different social, economic, environmental and political stakeholders. A first step would be issuing a solid diagnosis of the state of conservation and operation of mining facilities both operating and out of operation.

This is a complex task, given the poor supervision of government agencies in charge, the lack of a reliable public cadastre of these facilities, and the difficulty involved in gathering on-site data due to the restrictions imposed by private operating companies. The use of Remote Sensing to establish the geographic location of these mining facilities, in addition to offering advantages versus traditional methods, may be the only viable alternative for this purpose in some cases.

Aimed at the development of this diagnosis, this exploratory work developed the "J-Index" methodology that uses Remote Sensing for the preliminary location of tailings dams and currently operating and out-of-operation copper mining facilities; the primary objective is to facilitate its implementation by using current technologies that are broadly available, low-cost, quick, and easy to use; moreover, these should mitigate to some extent the constraints regarding resources, time and ease of access to the areas studied for monitoring the operation of such facilities.

The study area is located in the northwestern part of the State of Sonora. This includes the high portions of the Rio Sonora basin, a traditionally important mining area where the largest copper mine in Mexico is sited, and where the mining waste spill occurred in August 2014.

The construction and validation of the J-Index used photo interpretation of satellite images obtained from the Internet at Google Earth; the use of the Normalized Difference Water Index obtained from free images of the Sentinel-2 satellite of the European Space Agency; the list of the major mines currently operating or projected elaborated by the Mexican Geological Service obtained free of charge through the National Platform of Transparency; the list of users of underground sources developed by the Public Register of Water Rights obtained from the National Water Commission website; and the public software for analysis of Geographic Information Systems called Quantum GIS.

Its application in the northeastern part of the State of Sonora allowed validating its effectiveness in locating all the tailings dams and open-pit excavations of the known copper mines; also identified were areas corresponding to natural dams or lagoons not previously identified, with spectral characteristics similar to those of tailings dams and/or mining excavations. This will allow a more accurate focus in the additional field evaluations by both the relevant authorities and the mining companies themselves, to determine in greater detail the operating conditions, maintenance, and preventive and corrective measures, as applicable, to ensure a correct operation.

The reapplication of this methodology in other parts of the world will allow the identification of potential mining facilities, both currently operating or out of operation, that may involve potential hazards related to operation failure and their effects on the ecosystem.

Keywords : Environmental mining disasters; Integrated Water Management; Normalized Difference Water Index; location of tailings dams; remote sensing.

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