I think it refers to water.
Student or Learner
The following sentence is about Basra in Iraq, and its rivers anf geography. The words printed in bold are problematic. The underlined words are toponymic.
Rise and fall at Basra "about nine feet." The influence of the tides reaches about thirty miles beyond Kurna, but the stream always runs down, the rise and fall gradually decreasing to nil (Persian Gulf Pilot).
Does "rise and fall" reffer to land, or water of river?
Thanks very much.
I am not a teacher.