The paper deals with mathematical apparatus based on the method of dynamic programming. This method allows using the volume of unspent limit for irrigation withdrawal at specific weather conditions. The method of dynamic programming is based on the Bellman's principle of optimality, which formulated as following: control at every step should be chosen so that the sum of advantages was the optimal at all remaining until the end of the process steps including the advantage at the given step. According to the stated principle the dynamic programming is a directed linear search of possibilities which obligatory leads to a global maximum. The method of dynamic programming enables to create a mobile mechanism controlling irrigation withdrawal limits for variant planning and correcting water use plans at irrigation systems.
