International Conference «Mathematical and Information Technologies, MIT-2016»

28 August – 5 September 2016

Vrnjacka Banja, Serbia – Budva, Montenegro

Taseiko O.   Spitsyna T.P.   Radovanovic D.   Milosevic H.  

Biochemical Processes Of Self-Purification Model In Small Rivers

Reporter: Taseiko O.

The studying of water self-purification ability is a part of the problem of the regional limits developing of water quality that has the important role for the water quality management. The self-purification of natural water systems is a complex process that often involves physical, chemical, and biological processes working simultaneously. The complexity of this problem depends on heterogeneity of biotic and abiotic factors along a stream for every river. Natural process of self-purification for small river in sharp continental climate of Central Siberia is inhibited by low temperatures, rapid currents and poor development of plankton cenosis. The additional complexity for self-purification modeling in small river is diffusion sources as a results of agricultural practices.
This work shows that a simple model structure can be set up to describe the water quality in small river basins in terms of carbon and nitrogen compounds, when it is unfeasible to use complex models. The physical part of the model includes hydrodynamical components derived from SaintVenant’s equations, coupled to a transport model based on a convection-dispersion equation under non-uniform and unsteady flow conditions. Biological part of the model includes principle factors such as chemical and biological oxidation, concentration of biogene elements (nitrogen, phosphorus etc.). The main control parameters of this model are reaeration and biochemical oxidation rates. Nowadays, there is no method available to determine these rates that fit precisely to the reality of a given water body. It was found that the inclusion of non-point sources as piecewise constant parameters affects the identifiability to a considerable extent. In this article we used both mathematical modeling and natural sampling of surface water in some small rivers of Central Siberia for the control parameter assessment.
The methods of numerical modelling were used to estimate the principal parameters of developing model. These results have allowed to analyze the annual dynamics of the nitrification and denitrification rates, the mineralization rate of total phosphorus and organic nitrogen. The data of state monitoring network has allowed to verify the results of numerical calculations. The biochemical oxidation and reaeration rates have been specified under the impacts of natural-climatic conditions. The contribution of the main biochemical processes in the purification processes in the small rivers in the conditions of Central Siberia climate is estimated numerically. These estimations will use to develop purification model by adding new parameters.

This work was supported by RFBR grant 15-07-06982 and III 44006 MNRS

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