Cascade reservoir group design flood calculation method under multi-partition combination condition

The invention mainly relates to the technical field of water conservancy and hydropower engineering, and aims to solve the problems that when flood variables of all partitions are mutually independent under the condition of three or more multi-partition flood combinations, a multi-partition combination needs to be firstly converted into a plurality of pairwise partition combinations when the design flood is calculated by applying a discrete solution method; in order to solve the problems that the influence of reservoirs on flood is considered one by one in a cascade mode from upstream to downstream, and calculation is tedious, the invention provides a cascade reservoir group design flood calculation method under the condition of multi-partition combination, independent transformation is performed on the flood volume of each partition, and a theoretical frequency curve of a random variable obtained after the independent transformation of the flood volume of each partition is fitted; the theoretical frequency c