According to the quasi-least common multiples between lunar orbit periods and the earth’s orbit periods (i.e. Astro-climatic periods)

and using the flood records in earlier times (68-95 years ago)

the departure values of floods are estimated. Then the correlation coefficients between the estimated and the observed departure values are calculated.For six out of the eight rivers with long-term records

the reliability is larger than 92%. For five of them

the correlation coefficients are above 0.5. It is shown that the periodic orbit movement of the moon as an external factor can not be ignored in some regions of hydrology and meteorology