Computation of Aqueous Environment Contamination Parameters on the Basis of the Lagrangian Approach By B. Arkhipov, V. Solbakov, M. Solov’ev, and D. Shapochkin We present a mathematical model for a quantitative estimation of the damage to aquatic life resulting from a pollutant discharge into aqueous environment. With the use of the Lagrangian description of fluid motion, we introduce a set of hydrophysical parameters on the basis of which hydrobiologists can estimate the damage. The computation of these parameters is illustrated by the example of a problem of a pollutant spreading in a canal. The problem is solved numerically on a deformable Lagrangian grid. To ensure computational stability a special grid reconstruction procedure with the subsequent interpolation of the parameters computed is used. An original interpolation technique is proposed which ensures the preservation of the most important hydrophysical quantities. 1. Introduction During various hydrotechnical works in reservoirs, rivers, and coastal sea zones pollutants having negative impact on various groups of aquatic organisms, including food fishes and benthos, are released into the aqueous medium. The problem of the assessment of such man’s impact on aquatic organisms is of scientific, practical, and economical interest [1]. Nowadays mathematical modeling is one of the most important means of obtaining information about hydrophysical characteristics of aqueous environment needed to perform an environment impact assessment (EIA). Address for correspondence: Boris Arkhipov, Institution of Russian Academy of Sciences Dorodnicyn Computing Centre of RAS, Moscow, Russia; e-mail: arhip@ccas.ru DOI: 10.1111/j.1467-9590.2012.00561.x 1 STUDIES IN APPLIED MATHEMATICS 0:1–15 C  2012 by the Massachusetts Institute of Technology