St. Petersburg: RSMU Publishing House, 2004. — 198s. The book attempts to apply the ideas of partially infinite modeling to the process of forming long-term river runoff. We consider both the philosophical and methodological, as well as the scientific and natural grounds for such an approach, which is that the role of the "initial condition" is not played by the numerical values of the components of the state vector, but by the model itself that forms this dimension vector .. Partially infinite modeling is the formation of a model of an extended domain with a vector of the state of dimension, t. e. organization of a transitional epistemological process that cannot be fully rationalized. Addressed to specialists, graduate students and students of universities engaged in the hydrology of land.