The article analyzes methods for the determination of water consumption of crops. An algorithm for calculating sustainable water supply, which allows achieving high yielding capacity. On the basis of bioclimatic model of determining crops water consumption, the model of agriculturally used areas water consumption rationing is proposed, including the basic principles of land reclamation, improving of biological and preventing of geological circulation of water and chemicals. Developed algorithm for determining the rules of water consumption with the usage of meteorological data allows developing irrigation management software. The algorithm is very flexible, so it can be adapted to the specific features of the territory on which it is going to be used. This methodology can be applied in countries with arid climate. The proposed model would help to solve the problem of sustainable water consumption and irrigation of areas with inadequate water supply.