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Variability of concentrations of phosphorus forms under the conditions of weir renovation – The Głuszynka river-lake system case study
To fill the knowledge gap on the functioning of the river-lake system during the modernisation of the weir, an analysis of the variability of selected physico-chemical indicators was carried out. In the parameter analysis, particular emphasis was placed on phosphorus (P) and orthophosphate(V) (OP) content in the hydrological year 2022 and water quality was compared before, during and after the maintenance work on the discharge weir. Physico- chemical parameters were analysed monthly at four stations. Concentrations of P and OP increased significantly as a result of the refurbishment works at the measurement point located downstream of the weir (P4), which contributed to the determination of a statistically significant change point. At the same time, when high P and OP contents were observed, high electrolytic conductivity and ammonium nitrogen in water were also recorded. The content of P and OP indicators was further reduced, but their content was still several times higher than before the renovation. The renovation of the weir below Lake Jeziory Wielkie contributed to a significant deterioration of water quality in the river-lake system. Due to the nature of this system, this was of great importance for the downstream reservoirs. The statistical analysis showed that the renovation of the weir below Lake Jeziory Wielkie contributed to a significant deterioration of water quality in the river-lake system.
Ecological Importance of Alkaline Phosphatase Activity and Acid Phosphatase Activity in Lakes with Different Catchment Use Structures
Surface waters in Europe and across other continents have been affected by anthropogenic activities, leading to changes in the ecological state of lakes due to the continuous phenomenon of eutrophication. This study assesses the activity of enzymes secreted in bottom sediments collected from two lakes, aiming to determine the interaction between bottom sediments and water based on samples collected from lake bottoms and overlying water. The study measured the production of secreted enzymes via alkaline phosphatase (ALP) and acidic phosphatase (ACP) in two distinct environments. Sample collection encompassed two lakes within two diverse catchment types (agroforestry and forest) during spring and summer. The findings revealed higher ACP values than ALP in both lake environments, with higher enzyme values recorded in the lake with a typical forest catchment area. High values of enzymes were related to the pollutant’s input into the lakes, suggesting that anthropogenic activities may have a substantial influence on the studied lakes. Principal component analysis (PCA) allowed the identification of a negative correlation between the enzymatic activity of phosphorus in bottom sediments and the content of organic phosphorus (org-P) in overlying waters only within the forest catchment, where the angle between the vectors representing primary variables is close to 180 degrees. The conducted statistical analysis demonstrated significant distinctions among the lakes concerning most of the examined parameters.
Comparison of Two Hydrological Models, the HEC-HMS and Nash Models, for Runoff Estimation in Michałówka River
Floods are among the most devastating natural disasters in small suburban catchments. These phenomena, causing loss of life and massive property damage, pose a serious threat to the economy. Hydrological modeling is extremely important in terms of climate change, and the use of appropriate modeling can be a useful tool for flood risk prevention and mitigation. Rainfall–runoff modeling requires the selection of an appropriate hydrological model in order to obtain satisfactory results. Hydrological models are used in water resource planning and management to estimate catchment runoff. Small uncontrolled catchments play a particularly important role in hydrological phenomena, since changes in them affect flows in the recipient. Hydrologists are particularly interested in developing hydrological models that can be made with a minimum of data and parameters. Nash models and the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) are examples of simple and most practical hydrologic models. These models were used in this paper to study geographic and qualitative changes in precipitation runoff due to land cover changes. The modeling was carried out for two spatial aspects relating to the years 1940 and 2018. The model allowed for the simulation of the river flow that can occur under different rainfall probabilities. The analysis of the results was used to evaluate the hydrological models used. The hundred-year flow modeled with the Nash model for 1940 was 13.4 m3∙s−1, whereas the second model gave slightly lower flow values. In addition, modeling the flow for 2018 (after changing the land cover) highlighted the increase in the flow value for both models, where again the flow volume was slightly higher for the Nash model and amounted to about 19 m3∙s−1. The flow differences for individual models were not too large. This made it possible to conclude that the simulated outflow hydrographs are in good agreement, and this means that the models accurately reproduce the flow of the Michałówka River. The study showed that rapid urbanization adversely affects hydrological processes. In addition, the study showed that a well-distributed model can outperform a global flood forecasting model, especially in terms of magnitude, as in the current study example.