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Marin Palcu, Geo Aqua Consult ltd (Romania)
Gheorghe Witek, Geo Aqua Consult ltd (Romania)
Andrei Briceag, National Institute of Marine Geology and Geoecology (Romania)
Mihaela Melinte, GEOECOMAR (Romania)
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The lignite coal mining industry from SW Romania (Oltenia Region) produced quantitative impact and qualitative degradation of groundwater. Aquifer overexploitation (dewatering in coal mining area) due mining activity generated important groundwater depression area with water qualities changes. At the mining activity beginning, only the shallow aquifers were affected. In time, by deeply mining works progress, in regional main aquifer were produced serious modifications of groundwater flow.
By using geomorphologic, climatologic, hydrologic, and geologic-hydrogeologic investigations, a flow model for Upper Pliocene main aquifer system was developed. This model was used to elucidate aquifer status with hazard factors under drainage-dewatering system influence. Considering the aquifer local and regional non homogeneities, anisotropies and non linearity of parameters, the groundwater flow processes inside the main aquifer system were simulated. In the open and mining pit lignite exploitation, the dewatering process was produced dominantly by pumping of drainage wells. These dewatering systems create a large area of groundwater depression, which modified groundwater flow parameters, aquifer recharge, discharge, and by leakage water transfer between aquifers.
Human activity pollution in combination with groundwater flow modification determines degradation of the water quality. In time, chemical species such as organic substances, ammonia, nitrates and nitrites had a great migration inside the main aquifer. Additionally, an increasing concentration of chlorine by ascendant leakage from the deep aquifers in groundwater depression area was also remarked.
The resulting map and simulations indicate clearly the mining industry impact in regional area and the "hot spot" of potential risk on main granular aquifer from Upper Pliocene deposits. The result of impact assessment is an important basis for integrated groundwater management studies, in order to realize a long term planning of protective measures.
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