GIS-based environmental database for assessing the mine pollution: A case study of an abandoned mine site in Morocco

摘要

Morocco with important mining activities is increasingly concerned about impacts of mining on the environment. In Morocco, there are approximately 200 abandoned mine sites which vary from small scale underground mines to large scale open-pit mines. Some of these mines, with reactive tailings and waste rocks, are problematic. Indeed, Acid Mine Drainage (AMD) pollution from abandoned mines is responsible for soil and water contamination, land resources degradation, changes in landscapes, habitat destruction and human health hazards. In the current case study about the abandoned Kettara mine site, the impact of the old mining activity is assessed by the design and elaboration of an environmental database which will be supported by Geographic Information System (CIS) technology. This database includes multidisciplinary data related to geochemistry, hydrochemistry, hydrology, land cover, geology and climates. The current research demonstrated the efficiency of integrating multidisciplinary data and using CIS technologies when assessing the environmental impact of abandoned mines arid forecasting how the pollution is occurred. The obtained results show that in addition to the soil, the surface water and groundwater of the Kettara mine are also contaminated by pollutants which were previously released from mine wastes by AMD action. The sulphate content and the Electrical Conductivity (EC) of the surface water and groundwater are high. The average values for surface water are: sulphate ≈ 7920 mg/L and EC ≈ 25685 μS/cm. However, in groundwater they are: sulphate ≈ 2088 mg/L and EC ≈ 631 μS/cm. These values exceed the guidelines for drinking water quality prescribed by the World Health Organization (WHO) 600 mg/L and 1500 μS/cm for sulphate and EC respectively. The developed GIS based environmental database will serve as a reference study for other abandoned mine sites. Finally, it will be employed for the establishment of a web-based GIS Decision Support System which will assist decision makers in assessing and monitoring the occurred mine pollution.