I think 'sitting' means"The Prostitute who sits on many waters"
This is the same insymbology of the biblical passage as it does nowbook of Revelation, a harlot who sits on many waters. 'Sitting can have many different meanings, but in our daythe link below, a similar type of sitting is described.
See example at: http://www.businessinsider.com/stocks-gop-congress-sitting-democrat-president-2014-11
The terms used are 'sitting President" and mean one who is 'in office' and 'on the job', engaging'engaging in the tasks of their position.'
κάθημαι kathēmai- is the root , translated here and elsewhere as 'place', and 'dwell', so with these meanings we can put together - "the Harlot'ssitting Harlot (is in office) in her place where she dwells and engages in activity from."