I was reading an article about Design of elevated flumes (flume is a human-made channel for water). Here is a part of the article,
8.1 Data Requirement
Top Bank, TB
Water Surface, WS
Canal Bed, CB
My question is, what does Elevation of Top Bank mean? I looked up at OALD dictionary and I think bank refers to sense 5 "the side of a river, canal, etc. and the land near it". But still not sure about the meaning of the phrase. Does that mean elevation from top of a side of flume to the ground?