The paper focuses on research on improving the water supply of drainage systems of humid areas in the context of anthropogenic climate change. The aim of the research is to elaborate on the ways for increasing the available water supply of drainage systems and restoring active water regulation on reclaimed lands in a changing climate. Reclaimed lands are the main factor of sustainable agricultural production in Ukraine and guarantors of its stability. The area of drained lands in Ukraine is about 3.2 million hectares, including 2.3 million hectares drained with the help of closed drainage; in an area of 1.3 million hectares a two-way regulation of the soil water regime is carried out. An increase in air temperature and uneven distribution of precipitation, which has a torrential, local character in the warm period, do not allow for the e ective accumulation of moisture. The recurrence of droughts in di erent justified climatic zones of Ukraine has increased by 20–40%, which prevents sustainable agricultural production in the zone of su cient atmospheric moisture, in particular the Polesie Ecoregion. In this paper, the analysis of water consumption of reclaimed lands in the Polesie Ecoregion of Ukraine is carried out, on the examples of the drainage system “Maryanivka” and the calculation of the water supply for the corn and winter wheat.