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Concept and Implementation of Solutions Improving Water Relations in the Area of the Flooded Opencast Lignite Mine Kazimierz Północ in the East Wielkopolska Region (Central-West Poland)
Over a period of 30 years, the surface water level in the north-west of Konin, in the east of the Wielkopolska region, decreased by almost 6 m, resulting in a reduction of the surface area of the majority of nearby lakes, the disappearance of smaller water bodies and wetlands, and the drying out of streams draining the area. The causes of the decrease in the surface and groundwater level in the region are complex. They include both natural and anthropogenic factors, among others broad-scale mining activity. Based on knowledge of the hydrostructural composition of the analysed region and the functioning drainage system of opencast lignite mines, a concept was developed of a change in water supply to the flooded opencast lignite mine, Kazimierz Północ. The task of redirecting waters from the drainage of a nearby opencast mine, Jóźwin IIB, was implemented in 2020. Current observations and forecasts suggest that, owing to the applied solutions, the analysed opencast mine will be flooded in 2023, and not, as previously assumed, at the end of 2021. As a result, groundwater levels in the vicinity of the opencast mine as well as in lakes and rivers within the range of impact of the related depression cone will be restored faster, particularly in the Lake Powidzkie catchment. The objective of the study is to present stages of flooding of the former opencast lignite mine Kazimierz Północ, identify factors determining the process, and describe solutions accelerating it, with a simultaneous environmental impact assessment of the undertaken activities.
Agricultural Pressures on the Quality of Ground and Surface Waters in Catchments of Artificial Reservoirs
Changes in nutrient concentrations in groundwater were investigated to determine the impact of agriculture on water quality in artificial lakes. The study covered three reservoirs in an agricultural area of Wielkopolska (central-western part of Poland). Assessing the agricultural impact required a network of piezometers around the reservoirs, used to determine the degree of groundwater pollution from nutrients supplied to the reservoirs. Moreover, the analysis covered the quality of water in streams flowing into the reservoirs, and in the reservoirs themselves. Field research was conducted every month of the growing season from March to November. The analysis covered land inclination, ground permeability, and soil type. Detailed objectives included: (1) assessment of the agricultural impact on the chemical parameters of ground and surface water quality, and (2) evaluation of the impact of different sources of agricultural pollution on water quality in artificial reservoirs in regards to their management. This study revealed high dynamics of nutrient concentrations, particularly for nitrates and phosphates, in groundwater and surface water. A significant effect of maize cultivation on an increase in nitrate concentrations in the groundwater of the catchment of the Przebędowo Reservoir was evidenced, as well as a substantial effect of the functioning of an animal farm on the quality of groundwaters in the catchment of the Lachotka Reservoir. The nutrient load of agricultural origin in the catchment of the Miedzichowo Reservoir was relatively low. Our study revealed elevated amounts of nutrients such as nitrogen and phosphorus, detected more frequently in groundwater than in running waters, which confirms our hypothesis of the importance of groundwater analysis in detecting the source of pollution of the studied lakes. High nutrient concentrations recorded in groundwater leached from arable fields were also observed in the summer period, failing to confirm the hypothesis that the greatest effect of factors would be related to the spring effect of arable fields on water quality (lack of compact vegetation cover, high water level, etc.). Our study also indicated a greater importance of the type of land use than lithology or permeability of deposits.
How far from the shoreline? The effect of catchment land use on the ecological status of flow-through lakes
Hydromorphological pressure explains the status of macrophytes and phytoplankton less effectively than eutrophication but contributes to water quality deterioration
Water Management Instructions as an Element of Improving the State of the Pakoski Reservoir (Central–Western Poland)
The management of reservoir dams in the context of observed climate changes and changing environmental conditions is becoming an increasingly significant challenge. Changes in the regimes of rivers feeding the reservoirs, sudden floods, long periods of drought, shallowing of reservoirs, water pollution, and algal blooms create unprecedented threats to the operation of these reservoirs. Among these challenges, the most crucial seems to be the proper management of available water resources, which condition the existence of the reservoir. The location of the reservoir has a significant impact on how water management is conducted. In the case of mountain and upland reservoirs created for flood protection of areas downstream, water management practices differ significantly from those for lowland reservoirs, which primarily serve to retain water for industrial and agricultural needs in the area, with an additional flood protection function. The aim of this study was to assess the factors determining the supply of lowland reservoirs using the example of the Pakoski Reservoir (Central–Western Poland) and to propose actions that would allow more efficient management of water resources in the catchment and reservoir, enabling the preservation of the current morphometric parameters in the face of climate change, adverse environmental phenomena, and increased anthropogenic pressure in the catchment area. This study focused on the Pakoski Reservoir, located in the southern part of the Kuyavian–Pomeranian Voivodeship. It was constructed fifty years ago as a result of damming water in the river systems of the Noteć and Mała Noteć Rivers. For decades, it served its functions, and its management posed no major issues. However, over the past decade, due to environmental changes and human activities in the catchment area, the reservoir has increasingly faced problems with filling.
Effect of Water Level Reduction on the Littoral Zone in Terms of Its Efficiency in Lake Protection
Decreased water levels due to climate change cause many negative effects on lake ecosystems. The aim of this study was to (a) assess the effect of the reduction of water levels on nutrient availability in the sediment in the littoral zone; (b) evaluate the effect of changes in water level on biomass productivity and nutrient concentrations in the aboveground biomass of four emergent species: Phragmites australis (Cav.) Trin. ex Steud., Typha angustifolia L., Carex acutiformis L., Glyceria maxima (C. Hartm.) Holmb; and (c) assess the efficiency of the littoral zone in the reduction of nutrient pollution. The study hypothesis was that water level reduction has a positive effect on the plant biomass of high productive species. The study was carried out in the littoral zone of Tomickie Lake, situated in the western part of Poland. This lake is located in the protected area—the buffer zone of Wielkopolska National Park, and at the international level—Natura 2000. Six transects, perpendicular to the shoreline, were selected at two subzones—permanently and seasonally flooded. Analyses of nutrient concentrations in sediments and plant species were performed. The results show the higher productivity of reeds in the zone where water occurs seasonally at the site through the year, which reached 1193 g dry weight/m2. The decline of the water level may lead to the increased growth of highly productive species as emergent vegetation with a broad ecological scale in terms of nutrient concentrations and changes of water depth, i.e., Phragmites australis (Cav.) Trin. ex Steud. Species that prefer growth in the deeper part of the lake will be characterized by lower productivity, despite the high availability of nutrients. Changes in the availability of nutrients may cause the intensification of lake overgrowth by very productive species, which may affect biodiversity, which is particularly high in protected areas.