Use of tracers for study of flow, origin and evolution of chemical composition of spring water (Sv. Vojtěch, Bohemian Cretaceous Basin)
Abstract
Spring Sv. Vojtěch was studied using wide spectra of tracers.
In the past Sv. Vojtěch spring was important water supply for Kutná Hora town since 1495 till 20 th century.
Flow rate, temperature, conductivity, chemistry and oxygen composition was studied in spring water and also in water from sinkholes in spring catchment. Tritium activity, SF6 and freon 113 was studied in spring water as well.
Two fundamentally different types of porosity may be distinguished in spring catchment:1)water stored in matrix porosity(intergranular and fracture porosity) has vollume about 3 milion m3 and mean residence time about 23 years; 2)Karst conduits, which are draining matrix porosity have volume about 1200 m3 and mean residence time about 6-20 hours depending on flow rate.Maximum flow velocity in karst conduits is 15km/day.Spring is fed by two water sources: 1) Diffused recharge (autochthonnous and allochthonnous)and by 2)concentrated recharge from artificial drainage tubes drained to sinkholes.Second source accounts for 0-66% of total spring yield depending on water stage. First water source has higher concentrations of all ions except nitrates.Direct runoff (event water) component is negligible even during high flow rate.