Monitoring a hodnocení vodního toku Kyjovka

Abstract

This bachelor's thesis deals with the issue of surface water quality and the comprehensive evaluation of the current state of the Kyjovka watercourse from its source in the Ždánice Forest to its confluence with the Dyje river. The aim is to identify the main point and non-point pollution sources, assess spatial and seasonal changes in water quality, and evaluate the natural self-cleaning capacity of the stream under the influence of anthropogenic factors and extreme hydrological events. The method used was a one-year field monitoring conducted in regular monthly intervals from March 2025 to February 2026 at nine selected sampling profiles. Temperature, pH, conductivity, and dissolved oxygen were measured in-situ. Subsequently, organic pollution indicators (CODCr and BOD5) and nutrient levels (nitrogen and phosphorus) were analyzed under laboratory conditions. The obtained monitoring data were statistically evaluated and compared with historical data from 1991.The research revealed that while the upper course maintains very good water quality and the Koryčany reservoir successfully fulfills a stabilization and sedimentation function, the middle course represents a critically affected area. The most significant point source of pollution is the Kyjov wastewater treatment plant. Although the overall pollution load has significantly decreased since 1991, the discharged residual pollution constitutes the majority of the river's flow during the summer months. This extreme hydrological deficit and loss of the recipient's dilution capacity lead to massive oxygen depletion (down to 4.0 mg/l) and the loss of the river's self-cleaning ability. The research also confirmed the positive influence of pond systems on the lower course, which act as sedimentation basins, removing excess phosphorus from the water and thus protecting the Soutok protected area. The main finding is that a long-term sustainable state of the Kyjovka watercourse cannot be ensured merely by further tightening emission limits for polluters. A full remediation requires an integrated approach combining measures against non-point erosion and agricultural runoff, the completion of missing sewerage networks in municipalities, and, above all, the near-natural revitalization (renaturalization) of the heavily regulated riverbed to restore its natural self-cleaning processes. Keywords: Kyjovka River, water quality monitoring, surface water, pollution sources, physicochemical indicators.