Search Results (5)

The aim of this work is to evaluate core variables of the ecological potential of the Sulejów Reservoir (temperature distribution, flow velocities, and concentrations of selected indicators, e.g., phosphates, nitrates, the abundance of phytoplankton) using a three-dimensional hydrodynamic model, GEMSS-HDM (generalized environmental modeling system for surface waters), coupled with a water quality model, WASP EUTRO (GEMSS-WQM). The monitoring data necessary to build the model were obtained from two multiparameter probes that were submerged in two locations in the Sulejów Reservoir. An ADCP current profiler was used to collect data for hydrodynamic model calibration and verification. Total error between computed and measured velocity was estimated at 10–15%. A high concentration of chlorophyll-a during the vegetation season of 2015 (0.02 mg/L) was coupled with high water temperature (above 25 °C) and low concentrations of biogenic compounds (phosphorus and nitrogen at 0.02 and 0.001 mg/L, respectively). In 2015, NO₃-N was the limiting nutrient in the Sulejów Reservoir. Maximum growth of algae was observed in June and July 2015 (0.02 mg/L chla) along the entire length of the reservoir; algae bloom volume reduction was observed in September (0.004 mg/L chla). Proposed scenarios for nutrient reduction—50% reduction of phosphate-phosphorus (PO₄-P) and nitrate-nitrogen (NO₃-N) from agriculture areas as well as 50% reduction of discharges from septic tanks—led to a considerable reduction of nutrient concentrations in the reservoir waters; it additionally favors reducing the concentration of chlorophyll-a. The obtained results indicate that these sources of pollutants are mainly responsible for the poor water quality status of the reservoir and more intensive eutrophication phenomena. Full article

The aim of the presented research was to examine the concentration of biogenic compounds and heavy metals in the bottom sediments of the Sulejów Reservoir (Central Poland) from October 2018. Based on the obtained research results, maps of the spatial distribution were prepared. The following parameters were analyzed: total phosphorus (TP), total Kjeldahl nitrogen, total organic carbon (TOC), ratio of total organic carbon to nitrogen (C:N), organic matter content as well as Cd, Cr and Pb concentrations. The sediments were collected at 28 sampling sites, covering the whole area of the reservoir. The differences in the content of individual biogenic compounds result from the composition of the debris applied by the supplying rivers, as well as the content of this elements in the water, long retention time (40 days) and depth from which the tested sediments were taken. The distribution of examined compounds was largely influenced by the agricultural activity in the studied area, as well as the presence of ports and recreational points. Based on the measurements, the highest amounts of biogenic components deposit in sediments of deep parts in slow-flowing waters, in stagnation zones, areas adjacent to arable land, and the sites where fine-size fractions prevail in the deposited material. Biogenic compounds in sediments of the Sulejów Reservoir showed a pattern of gradual increase along the reservoir from lower values in the back-water part. A similar relationship is visible for heavy metals. Referring to the ecotoxicological criteria, it can be stated that bottom sediments from the Sulejów Reservoir collected in 2018 are not toxicologically contaminated in terms of cadmium, lead and chromium content. Full article

The paper presents results of water quality monitoring conducted within the frame of the MONSUL project. The main goal was to analyse and assess the impact of factors determining the ecological status of a dam reservoir on the basis of the Sulejow Reservoir located in Central Poland. The project implementation plan based on comprehensive research-based monitoring covered the following parameters characterising the ecological potential of the reservoir: water temperature, pH, oxygen concentration, chlorophyll “a” and blue-green algae, concentration of ammonium ion, nitrate nitrogen phosphates as well as total organic carbon, chemical oxygen demand and biochemical oxygen demand. The parameters were measured with a mobile and stationary monitoring system and supplemented by an off-line analysis of water samples in the laboratory. The study was carried out during two seasons: May–October 2015 and April–November 2016; the results were analysed also with regard to the weather conditions. Despite the similar temperatures of water and air in the analysed seasons, significant differences were observed for atmospheric precipitation; 2015 was a dry year, and the climatic water balance for the analysed area was negative, which caused limited surface runoff and decreased the concentrations of nutrient in the reservoir waters. Data from continuous monitoring, supplemented with the results of laboratory measurements, indicated that the values of TOC (Total Organic Carbon) and COD (Chemical Oxygen Demand) parameters were within the purity class I; exceedances refer to the BOD (Biochemical Oxygen Demand) value, which confirmed the presence of biodegradable organic compounds in the reservoir waters. The values of chlorophyll “a” and the presence of algae during the vegetation season testify to eutrophication of the Sulejow Reservoir. Full article

The objective of this paper was to spatially quantify diffuse pollution sources and estimate the potential efficiency of applying riparian buffer zones as a conservation practice for mitigating chemical pollutant losses. This study was conducted using a semi-distributed Soil and Water Assessment Tool (SWAT) model that underwent extensive calibration and validation in the Sulejów Reservoir catchment (SRC), which occupies 4900 km2 in central Poland. The model was calibrated and validated against daily discharges (10 gauges), NO3-N and TP loads (7 gauges). Overall, the model generally performed well during the calibration period but not during the validation period for simulating discharge and loading of NO3-N and TP. Diffuse agricultural sources appeared to be the main contributors to the elevated NO3-N and TP loads in the streams. The existing, default representation of buffer zones in SWAT uses a VFS sub-model that only affects the contaminants present in surface runoff. The results of an extensive monitoring program carried out in 2011–2013 in the SRC suggest that buffer zones are highly efficient for reducing NO3-N and TP concentrations in shallow groundwater. On average, reductions of 56% and 76% were observed, respectively. An improved simulation of buffer zones in SWAT was achieved through empirical upscaling of the measurement results. The mean values of the sub-basin level reductions are 0.16 kg NO3/ha (5.9%) and 0.03 kg TP/ha (19.4%). The buffer zones simulated using this approach contributed 24% for NO3-N and 54% for TP to the total achieved mean reduction at the sub-basin level. This result suggests that additional measures are needed to achieve acceptable water quality status in all water bodies of the SRC, despite the fact that the buffer zones have a high potential for reducing contaminant emissions. Full article

Ground-based precipitation data are still the dominant input type for hydrological models. Spatial variability in precipitation can be represented by spatially interpolating gauge data using various techniques. In this study, the effect of daily precipitation interpolation methods on discharge simulations using the semi-distributed SWAT (Soil and Water Assessment Tool) model over a 30-year period is examined. The study was carried out in 11 meso-scale (119–3935 km²) sub-catchments lying in the Sulejów reservoir catchment in central Poland. Four methods were tested: the default SWAT method (Def) based on the Nearest Neighbour technique, Thiessen Polygons (TP), Inverse Distance Weighted (IDW) and Ordinary Kriging (OK). =The evaluation of methods was performed using a semi-automated calibration program SUFI-2 (Sequential Uncertainty Fitting Procedure Version 2) with two objective functions: Nash-Sutcliffe Efficiency (NSE) and the adjusted R² coefficient (bR²). The results show that: (1) the most complex OK method outperformed other methods in terms of NSE; and (2) OK, IDW, and TP outperformed Def in terms of bR². The median difference in daily/monthly NSE between OK and Def/TP/IDW calculated across all catchments ranged between 0.05 and 0.15, while the median difference between TP/IDW/OK and Def ranged between 0.05 and 0.07. The differences between pairs of interpolation methods were, however, spatially variable and a part of this variability was attributed to catchment properties: catchments characterised by low station density and low coefficient of variation of daily flows experienced more pronounced improvement resulting from using interpolation methods. Methods providing higher precipitation estimates often resulted in a better model performance. The implication from this study is that appropriate consideration of spatial precipitation variability (often neglected by model users) that can be achieved using relatively simple interpolation methods can significantly improve the reliability of model simulations. Full article