Abstract
The quality of surface water in Czechia continues to be an ecological problem, also in rural areas. The Šlapanka River catchment belongs to one of these areas, and this study aims to determine what changes occurred between 1977 and 2020, with particular attention paid to the years 2002 and 2014.
Due to the agricultural character, an emphasis was placed on nutrient monitoring. Several water quality parameters were monitored: water temperature, dissolved oxygen, conductivity, pH, nitrate and ammoniacal nitrogen, phosphate phosphorus, and organic substances.
The average and characteristic values of concentrations were used to evaluate the time series of water quality parameters, and Mann-Kendall statistical tests were used to examine trends. Data were analyzed using multivariate statistical methods.
In 2002, the water quality in the river basin was marked as heavily polluted, but by 2014, the water quality had improved in most monitored locations. Nitrates and organic substances concentrations differed significantly in the headwater catchments between 2002 and 2014.
Nitrate concentrations were lower and organic substances were higher. Similar results were encountered in the longitudinal profile.
Between 2002 and 2014, nitrate concentration levels dropped, mainly in the upper part of the river, while ammonium concentrations declined in the lower part. Over the same period, the number of organic substances increased in the middle part of the river.
In contrast, phosphate phosphorus concentrations increased, though primarily downstream. Nonpoint sources slightly predominate, especially in the upper parts of the basin.
Therefore, changes in agricultural praxis are the key to improving water quality.