Abstract
<jats:p>Distinctive features of the modern approach to solving the problem of assessing the maximum permissible withdrawal of river flow and the release of environmental flow include consideration of the nature and scale of water resource use and their impact on the natural environment, as well as an assessment of their effects on ecology, the economy, and society within river basin catchment areas. The aim of the study is to develop a methodological approach to assessing the maximum permissible withdrawal of river flow and the release of environmental flow, taking into account geo-ecological constraints. Materials and methods. The research methodology includes two approaches to substantiating the volumes of these quantities, based on the development of mathematical models of hydrological–ecological and economic activity of river basin catchment areas. The study used statistical data from government agencies of the Republic of Kazakhstan and the Kyrgyz Republic. Results. General principles, criteria, parameters, and methods for regulating the maximum permissible withdrawal of river flow and the release of environmental flow are proposed, based on modeling natural and anthropogenic processes in river basins. An algorithm for approbation within the framework of calculating standards of permissible impact for specific river basins is presented. Conclusions. The use of mathematical models makes it possible to carry out a more in-depth hydrological, ecological, and economic justification, contributing to the improvement of the socio-ecological situation within river basin catchment areas.</jats:p>