Formation of a Favorable Filtration Regime of Soils in Saline Areas of the Danube Delta Rice Irrigation Systems

The environmental state of rice irrigation systems (RIS) is determined by many factors, including natural ones (soil, topographical, hydrogeological, and climatic factors) and technological ones (irrigation norm, design, and parameters of irrigation and drainage networks, etc). The most significant influence on the ecological reclamation state of the RIS carries is effected by its drainage network (DN). The need to maintain a flushing water regime with specific filtration rates to prevent secondary salinization in the Danube Delta’s rice systems is a crucial aspect of managing these agricultural areas. In the saline areas of rice systems located in the Danube Delta, the DN must ensure the maintenance of the flushing water regime with the rates of filtration ranging between 10 to 12 mm/day. This is a prerequisite for preventing secondary salinization of irrigated lands of these rice systems. According to the results of studies, the filtration from the surface of the irrigation checks of the Danube Delta RIS has been established, and its values in the area of the rice check vary significantly. Different intensity of filtration in the area of rice checks causes the difference in mineralization of groundwater and in the content of salts in the soil. This leads to the fact that the same rice check created various natural reclamation conditions and different productivity of cultivated crops.