1. A pop-up menu has been set up with pre-selected periods based on the Streamflow Sequences at this website: 

2. The description of each streamflow sequence is in the blue menu window
The orange horizontal lines in this panel represent the running mean for the period ending with the 25 year simulation of each basin 
First example: The simulation is for 25 years, but starts with the first year of the 7-year sequence (1579)
The description of each streamflow sequence is in the blue menu window