When carrying out environmental impact assessments related to the discharge of pollutants into the aquatic environment, the question arises of estimating the extent of pollutant distribution and the magnitude of damage to bioresources due to pollution of the aquatic environment. Mathematical modeling is one of the most important means to obtain this information, represented as a set of hydrological quantities, which are the basis for biota damage assessments. In the present work mathematical definitions of these quantities are given and results of their calculations are given on the example of specific problems. The natural method of defining and calculating these is to use the Lagrangian approach. However, in the process of modeling there are significant deformations of meshes and the need for interpolation to a regular grid using an algorithm that conserves the values of the basic functionals. The present work also shows that the required parameters can be calculated in the Eulerian approach too, for this purpose the advection equation of a specially defined value is to be solved. The test simulations demonstrate a satisfactory coincidence of the calculation results with the analytical solutions.