A short term dependence analysis does not show long range dependence. There are small changes occurring from year to year that short term dependence cannot indicate. The most prominent case would be the major flood of the Red River Valley in Winnipeg in 1997. Dr. Lye has used this data in his research. One of his findings was the relation between the flooding and the soil moisture stored in the heavy soils of the Red River basin.
Heavy soil holds water for years and can cause potential flood risk.
It only shows that high flooding tends to come together in bunches. It is very clear in the Red River flood series that there is a bunch of low floods in 1930s and 1940s. There is no cyclical effect. It is that they just tend to bunch together. Long range dependence does not necessarily mean that a flood 100 years ago will have an influence on flooding today.