Dependence of Selected Water Quality Parameters on Flow Rates in River Profiles in the Czech Republic

Abstract

The article analyses dependence of water quality parameters on flow rates in several profiles in the Vltava River catchment in the Czech Republic in the period 1997 - 2013. In  study, influence of low flow rates on the water quality is assessed on several examples of river profiles, tributaries and outflow of the Orlík Reservoir, which is located at the Vltava River in the Czech Republic. At these sites, we monitored changes in general parameters of the water quality - temperature (T), pH, dissolved oxygen (O2), chemical oxygen demand permanganate (CODMn), chemical oxygen demand dichromate (CODCr), biochemical oxygen demand (BOD5) a suspended solids (SS), nutrients – nitrate nitrogen (N-NO3-), ammonia nitrogen (N-NH4+), total phosphorus (PT) and phosphate phosphorus (P-PO43-) and further quality parameters – dissolved solids (DS), dissolved inorganic salts (DIS), calcium (Ca2+), magnesium (Mg2+), potassium (K+), chlorides (Cl-), sulphates (SO42-) and qualitatively also non-polar extractive substance (NES) a anion-active surfactants. The assessed period was 1997-2013. Aim of the study was to evaluate relationship between mentioned parameters and the flow rates in days, when the samples were taken. Furthermore, ratios of average parameters values during low and high flows were calculated. The results show that in the monitored profiles, there is a direct relationship with flow rate in case of N-NO3-, suspended solids and O2. Temperature shows an inverse relationship with the flow rate. Other parameters show different relationship with the flow rate in individual monitored profiles or do not show statistically significant relation.

Keywords

• Water quality
• flow rate
• point pollution source
• nonpoint pollution source
• drought
• flood