Aim of the study: The study evaluated verification of empirical formulas for calculating mean low flow (MLF) in reflect to shaping disposable water resources for mountain catchments, located in upper ...Vistula Basin. The following empirical formulas were analyzed: Punzet and Stachý. Material and methods: The studies were conducted according to following stages: analysis of significant trends for low flows in analyzed catchments, the mean low flows determination using analyzed methods, determination of disposable water resources regarding to MLF obtained from analyzed methods. Results and conclusions: The analysis showed lack of significant trends in low flows courses for analyzed catchments. Also the analysis indicated significant differences between MLF derived from hydrological data and empirical formulas. The obtained results indicated the need to update empirical formulas for calculating MLF especially regarding to disposable water resources determination, in ungauged catchments, in reflect to mean low flows.
The paper constitutes the analysis of hydraulic load of a local wastewater treatment plant in the south-eastern Poland along with the analysis of sewage receiver hydraulic capacity and related ...receiving waters protection. Assuming that the daily outflow of treated sewage should not exceed 10% of the mean-low flow (SNQ) of the receiver, no case of daily sewage outflow greater than 10%·SNQ = 51 840 m3·d-1 was recorded. Moreover, average daily hydraulic load of the treatment plant was lower than the limit value by over 70% and the maximum recorded value – by over 40%. Furthermore, the conducted analysis shows that the particular months differed from each other in the values of the daily hydraulic load of the wastewater treatment plant at the outflow; May was the month with the highest average daily sewage outflow, while September was characterized by the lowest average daily outflow of treated sewage. There was also no clear dependence between the hydraulic load of the WWTP and the day of the week. Daily sewage outflows ranging from 10 000 m3·d-1 to 12 000 m3·d-1 constituted the largest part of all observations. The daily sewage outflows directed to the receiver prove that there is no threat to the preservation of the water environment quality.
Aim of the study: i. Comparison of characteristic discharges (mean and mean of annual minimum, i.e. mean low discharge) of small lowland river between two periods (1963-1990 and 1991-2020) estimated ...on the base of field measurements. ii. Comparison of specific discharges of two small catchments of various size in the period 1991-2020. iii. Evaluation of local indirect methods for estimation of mean and mean low discharge applied for the two small catchments. Material and methods: Since 1962, hydrological investigations have been conducted in a small lowland catchment of the Zagożdżonka River. The catchment area is characterized by agro-forested land use, and is located in the south part of the Masovia region, Poland. Continued monitoring of water stages and discharge measurement at the river gauge Płachty Stare were conducted for estimating daily and characteristic discharges for two periods: 1963-1990 and 1991-2020. Other methods were also used for both of the hydrological characteristics. They were based on maps of specific discharges from the Hydrological Atlas of Poland. Results and conclusions: Mean discharge of the Zagożdżonka River at the gauge Płachty Stare between the two periods decreased by 24%. Mean low flow decreased by 43%. Higher evapotranspiration, caused by climate change, i.e. temperature increase and higher ratio of forested area in the catchment, is indicated as the main reason of the changes. Mean specific discharge from the smaller catchment (at Wygoda gauge) was 36% less than from the larger catchment. The application of the indirect methods for estimation of mean and mean low discharges for the larger catchment seems to give satisfactory results.
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