Review of Studies of Flooded Areas and Water Balance of the Volga Delta during High Water Period

This review of studies of the flooded areas of the Volga Delta (VD) (Ftot) and the water balance (WB) of the VD during floods is a base of accumulated knowledge about the features of Ftot and WB during floods and the methods of their study. The advantages and disadvantages of these methods are analyzed. It is revealed that the studies of Ftot and WB during floods are not complete; only approximate daily Ftot and approximate daily WB parameters for some floods were obtained. Therefore, the features of Ftot and WB during floods of different water contents have not been fully identified. Research methods have changed and improved; hence, the accuracy of the approximate daily Ftot and approximate daily WB parameters estimated by different methods for different floods vary significantly. The results of such calculations cannot be analyzed jointly. It will be impossible to supplement future studies with high accuracy with the results of such calculations. However, due to the appearance of new technologies and a large amount of satellite data, the methods can be implemented in the latest studies, obtaining highly accurate results. As a result, the following problems remain unsolved: calculating daily Ftot and daily WB parameters for floods of different water content with high accuracy using high-tech methods with a large number of space images and identifying spatiotemporal patterns and distinctive features of floods of different water content by daily Ftot and daily WB parameters.