No abstract

The watershed model SWAT (Soil and Water Assessment Tool) can be used to implement the requirements of international agreements that Poland has ratified. Among these requirements are the establishment of catchment-based, rather than administrative-based, management plans and spatial information systems. Furthermore, Polish law requires that management of water resources be based on catchment systems. This article explores the use of the SWAT model in the implementation of catchment-based water management in Poland. Specifically, the impacts of basin size on calibration and on the results of the simulation process were analyzed. SWAT was set up and calibrated for three Polish watersheds of varying sizes: (i) Gąsawka, a small basin (>593.7 km), (ii) Rega, a medium-sized basin (2766.8 km), and (iii) Warta, a large basin (54,500 km) representing about 17.4% of Polish territory. The results indicated that the size of the catchment has an impact on the calibration process and simulation outputs. Several factors influenced by the size of the catchment affected the modeling results. Among these factors are the number of measurement points within the basin and the length of the measuring period and data quality at checkpoints as determined by the position of the measuring station. It was concluded that the SWAT model is a suitable tool for the implementation of catchment-based water management in Poland regardless of watershed size.

No abstract

Water eutrophication still causes many environmental and social problems, and so better quantification of the amount of nutrient loads discharged into surface waters is required. The basis for eutrophication analysis is data gathered in the frame of State environmental Monitoring (SeM). in Poland, these measurements are carried out at the frequency of 6-12 times per year and serve as the basis for calculating the amount of nutrient input discharged to the sea. This article presents the results of the analysis of the representativeness of one measurement make two-hourly per day of the variability of total nutrient concentrations. For this purpose three cycles of field studies were carried out in accordance with plant growing season. The measurements were taken in november 2013, February 2014, and June 2014 in the słupia river, at the site where it flows through the village of charnowo (river profile). the analysis showed a significant change in the amount of total nutrient concentration during the day (up to 60% for total nitrogen and total phosphorus). This trend was maintained regardless of the stage of plant growth. Therefore, both the date for water sample collection and the time the measurement was taken become important for the subsequent evaluation of nutrient loads discharged into the sea. it is reasonable to assess the level of nutrient loads discharged into the sea not on the basis of a single measurement but based on the continuous registration of nutrients-this allows us to assign a daily average. it is also important from the point of view of the calibration of mathematical models, which are now an essential tool for analysing and forecasting environmental changes, and for which access to detailed data is very important.