Sulphate Balance of Lakes and Shallow Groundwater in the Vasavere Buried Valley, Northeast Estonia

Abstract

Groundwater is an important component of many water resource systems supplying water for domestic use, industry, and agriculture. Management of a groundwater system, an aquifer, means making such decisions as annual withdrawal of the total quantity of water, location of wells for pumping and for artificial recharge and their rates, and control conditions at aquifer boundaries. The decisions related to groundwater quality are of no less importance. In fact, the quantity and quality problems cannot be separated. In many parts of the country, with the increased withdrawal of groundwater, the quality of groundwater has been continuously deteriorating. In recent years the attention has been focused on groundwater contamination by mine water. A thorough understanding of the system, and the processes that take place in it are needed for modeling procedure. It is important to identify those parts of the system's behavior that are relevant to the considered problem, while other parts may be neglected. On the basis of this understanding, summarized as a conceptual model of the given problem, a numerical model was constructed. Using the conceptual model the groundwater flow model of the Quaternary aquifer, in the eastern part of oil shale deposit area, in the Vasavere buried valley, was constructed. The infiltration of contaminants grows, and the Quaternary aquifer is polluted by sulphate in a large area of the Vasavere buried valley.

Influence of the Bedrock Topography on Oil Shale Mining in North-East Estonia

“…On the other hand, the hydrological regime in the valley has been influenced by oil shale mining. The content of sulphate in the surface and groundwater indicates directly the influence of the mining water [22]. The comparatively intensive and uneven water exchange with surrounding mines has been clearly caused by the uneven bedrock topography.…”

The Impact of Infiltration Dam on the Groundwater Regime in the Kurtna Landscape Reserve Area

“…The influence of mining on the lakes has been investigated from the hydrogeological aspect, recommending the usage of infiltration basins and regulation of water flow [10][11][12][13][14]. Water chemistry has been investigated proceeding from the effect of oil shale mining on sulphate content of water [15]. The influence on the landscape and plants has been studied by analysing plant species and mining waste [16][17][18][19].…”

Impact of Oil Shale Mining and Mine Closures on Hydrological Conditions of North-East Estonian Rivers

“…2. Therefore, interaction between all considerable components of water circulation scheme (infiltration of precipitation water into the mines, mine water pumped out into the rivers, groundwater exchange between closed mines and movement at the sites of tectonic damage, total river flow into the Gulf of Finland and Lake Peipsi) for Purtse, Pühajõgi, Vasavere and Rannapungerja rivers is of a combined and developed character [4,14].…”