One of the widely used methods of integrated river basin management is the modeling of surface water runoff using ordinal flow curves (or CN curves). This method was developed by the Department of Conservation of Agricultural Natural Resources of the United States. This method uses an empirical parameter to predict direct surface runoff and takes into account the spatial structure of the landscape, i.e. the current state of land use. The purpose of the method of landscape-ecological synthesis in relation to the foothill zones of the river basin is to determine the water potentials of such zones. At the same time, the question is raised of creating an ecologically optimal landscape structure suitable for any type of ecological complex in the landscape. At the same time, the landscape of foothill zones is characterized by a variety of natural and geological structure and the indicator of water retention in such zones cannot be characterized by a single value. In this article, the following question is solved: what should be the relationship between the total volume of rainwater and the indicator of potential water retention in the zones of the foothill landscape, so that the total amount of surface runoff in all zones of the foothill landscape reaches a minimum value. The issue of optimizing the total surface water runoff in various zones of the foothill landscape located in the river basin is being investigated. The problem of finding conditions for achieving the lowest volume of surface runoff in foothill areas has been formulated and solved. It is determined that the minimum volume of surface water runoff can be obtained if there is a linear relationship between the total volume of rain flows and the value of the indicator of potential water retention in various areas of the landscape, provided that the total volume of rainwater in all zones remains unchanged.