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Sediment management in reservoirs – methods of sediment handling, sediment reevaluation to product - stabilized solidificate
Vrzák, J. ; Borovec, Jakub ; Jan, Jiří
As part of the research work, a semi-operation was set up and a test polygon (''island'') was built on central Novomlýnská reservoir (Věstonická reservoir). The sediment excavation and its transformation into different type of ''products'' in a special mixing plant. The stabilised solidified product was subsequently used in the construction of the new island. The new island will be used this year for monitoring, including, among other things, the behaviour of the new sediment structural elements, its shape stability and other parameters. As part of the protection of the island from wave action, also from solidified sediment, experimental constructions of submerged breakwaters have also been created. Another way of using the stabilised solidified sediment is outside the reservoir, for example in earthworks and to create a stock of ''soil'' for other construction activities.
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Content of iron and quality of organic matter as a factor affecting stabilization of carbon and nutrients in fresh water ecosystems.
Osafo, Nana O. A. ; Jan, Jiří ; Porcal, Petr ; Borovec, Jakub
The effect of watershed geochemistry, in terms of soil pH, Fe concentration and organic matter quality, on the stability of organic carbon and nutrients level in freshwater sediments of shallow lakes was studied. Twelve fishponds were divided into two groups based on the typical soil pH: i) watershed with acidic soils (pH 5.1 – 6.3) rich in Fe called H_Fe and ii) watershed with neutral pH soils (pH 6.8 – 7.6) poor in Fe called L_Fe. The parameters of the water column, pore water and sediment chemical extractions were compared. A higher concentration of hydrated Fe oxides, together with the aromatic character of organic substances were shown to highly contribute to the overall stabilization of the sediment. Conversely, low Fe concentrations were accompanied by lower mineralization of sediments and a higher risk for the aquatic ecosystem in terms of nutrient release or the development of anoxic conditions.
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Use of a research sonar to determine sediment thickness
Borovec, Jakub ; Vrzák, J. ; Knotek, J.
The study summarizes research results aimed at the identification and quantification of sediments in freshwater reservoirs. An algorithm for the interpretation of sonar data, and the calculation of sediment thickness as well as for the estimation of basic sediment characteristics was developed. A device for the collection of sediment cores, which are used for the calibration of sonar output data was introduced.
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Methodology for identification and quantification of sediments in water reservoirs
Borovec, Jakub ; Jan, Jiří ; Vrzák, J. ; Knotek, J.
Our contribution briefly introduces the Methodology for the assessment of sediments, which was certified by the Ministry of agriculture of the Czech Republic under the registration number 13084-2017-MZE-15000. The Methodology finds its use especially among the managers and owners of various water works, reservoirs, and ponds, but also project architects and implementation companies who come across and need to resolve many sediment-related problems. The Methodology also serves as a basic introduction into the problematics of reservoir sediments, but primarily offers the correct and most effective procedures, which should ensure significant savings and eliminate potential risks.
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Sedlice Reservoir – coagulation experiments of sediment samples
Borovec, Jakub ; Jan, Jiří ; Tomková, Iva
The study was conducted on the basis of a contract between the Vltava River, State Enterprise and the Biology Centre CAS. The subject of the study comprised of sediment sampling from Sedlice Reservoir (Czech Republic) and coagulation experiments on these samples in order to find optimum conditions for dredged sediment dewatering using geotextile tubes and flow centrifuges. Results will serve to find optimum coagulation conditions to ensure maximum purification of the effluent from nutrients or contaminants during the process of sediment dewatering.
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