Methods of Calculating Daily Flooded Regions of the Volga Delta During Flood Periods Using Satellite Data

A method for calculating daily flooded regions of the Volga Delta (VD) over the entire flood period using satellite data has been developed. The method is based on constructing dependencies of flooded areas of the channel network and interbranch spaces of the VD region (F_total) on daily mean water levels in the channels of watercourses (H_p) over the territory of the VD region. The value of F_total for individual flood dates is determined using satellite images (space images). Data on H_p from pressure gauge stations on the same dates are taken from the State Water Cadaster. Using these dependencies, daily flooded areas of the VD region are calculated with high accuracy for floods of different water content (high-water, low-water, and medium-water). The technique has been developed in two versions: (1) the technique using a sufficient number of space images to cover all the main changes in the course of each flood phase and (2) the technique using an insufficient number of space images to cover all the main changes in the course of each flood phase. A comparative analysis of the daily F_total obtained with high accuracy by technique (1) for floods of different water content (high-water, low-water, and medium-water) has been carried out. It has been revealed how floods of different water content differ in characteristics (passage time, amplitude, area of maximum flooding of the territory, duration of the rise phase, recession phase, and flood plateau phase). This result has been obtained for the first time. The results of calculations by this technique make it possible to identify spatiotemporal patterns in the flooding processes of the VD region during floods of different water content. Using this technique, it is possible to predict the course of floods in the VD region and calculate the water balance of this region.