Practically all sources of fresh water suitable for agriculture, water supply to the population and vacationists, as well as for industrial development on the Black Sea coast of the Caucasus either have completely exhausted themselves or are on the verge of their possibilities. Further development of the region is directly related to the resolution of this problem. The solution of the problem is possible when the system for regulating precipitation flow is implemented. The proposed system includes small reservoirs located in canyons of mountain gorges. Moreover, it is proposed to create in the gorge both above-ground and underground reservoirs for accumulation of surface and underground flow. Complex hydro-geological conditions of construction, seismicity of the zone, suggest the construction of lightweight buttress dams in the structure of hydrosystems, when the pile foundation directly perceives horizontal shear forces. Complex formulation of the issue required the use of mathematical modeling of the situation on the basis of 3D production, with the analysis of the stress-strain state of the "foundation-dam" system. Dynamic analysis (calculation of eigenvalues) and analysis of seismic impact on the dam are carried out. The carrying capacity of the buttress dam was estimated and the degree of reinforcement was determined, as a result of which it was established that the proposed construction complies with regulatory requirements. Design solutions for the system of regulation of precipitation flow were introduced in production in 2016 in the suburbs of the resort town of Gelendzhik. Successful operation of the system confirms the correctness of theoretical and technological prerequisites and opens up new opportunities in the intensive development of the Black Sea coast of the Caucasus. The proposed system for regulating atmospheric runoff can find application in other regions of the mountain-foothill zone, for example, in the countries of Central Asia.