National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Prediction of phosphorus concentration and trophic conditions in reservoirs
Hejzlar, Josef ; Kopáček, Jiří ; Vystavna, Yuliya
The model prediction of phosphorus (P) concentration in reservoirs is important for controlling water quality and trophic conditions, e.g. to determine to what level external P load should be reduced in order to decrease trophic conditions and achieve good ecological potential. The mass balance of P for 26 reservoirs and lakes in the Czech Republic showed that the relationship between the inflow P concentration and the in-reservoir P concentration is not determined solely by hydrological parameters (water residence time or hydraulic load) or inflow P concentration but is fundamentally influenced by the internal P loading from sediments and in-reservoir P cycling. These are individual characteristics of each reservoir and may change, for example with sediment accumulation or changes in external P load. Therefore, the prediction models need to be assembled and calibrated for each reservoir individually and the model structure should be adapted to their specific conditions.
Phosphorus concentration in the Orlík and Slapy reservoirs: a result of socio-economic trends in the catchment and climate change
Hejzlar, Josef ; Jarošík, Jiří ; Kopáček, Jiří ; Vystavna, Yuliya
Based on existing phosphorus data series in the Slapy and Orlík reservoirs and their main tributaries, we reconstructed P inputs to the reservoirs from the catchment during 1961–2016 and compiled\nempirical models of P retention. P concentrations in both reservoirs increased from the 1960s to 1991 and then declined, with the Slapy Reservoir having a significantly increased year-on-year\nvariability. Trends in the increase and decrease of P reflected the socio-economic development in the Vltava river basin, in particular sewerage, wastewater discharges, fertilizer application, livestock,\nand fishpond fisheries. In the Slapy reservoir after 1991, the P concentrations increased during wet summers and created conditions for growth of phytoplankton, whereas in dry summers they\ndecreased to mesotrophy. Climatic and hydrological processes have now apparently begun to compete with a generally decreasing P pollution and support eutrophication despite the drop in P loads from the catchment.

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