MODELING OF THE СHANNEL AND BASIN COMPONENTS OF RIVER SOLID RUNOFF (USING THE EXAMPLE OF THE NARVA RIVER)

Abstract

The processes of two-phase mass transfer and transport of dissolved substances in the ‘catchment – water
body’ system determine the spatiotemporal redistribution of these geochemical components throughout the hydrographic
network. At the same time, the products of soil erosion not only can pose a threat of siltation but also are sources of
pollutants adsorbed on the surface of soil-ground particles. The developed model of the channel and basin components of
solid runoff is based on the assessment of the transporting potential of the watercourse and the dynamics of the curves
showing the granulometric composition of bottom sediments, products of soil and channel erosion. The model makes it
possible to estimate the intensity of redistribution of river and bottom sediments in the riverbed. At the same time, the model calculates the profile of changes in the bottom marks between the two calculated channels, the size distribution of
the particles deposited or set in motion, the particle mass of the channel and basin components of sediment runoff, and
the contribution of the basin component. Calculations for the Narva River have shown that the contribution of the basin
component to the solid flow of this watercourse is about 98 %. The results obtained are in good agreement with the results
of modeling soil erosion in the Narva River catchment and are confirmed by the unexpressed dynamics of channel deformations of the studied section of the watercourse.