Once the water flow exceeds the bank elevation and the river's predetermined flood stage, even pumping at maximum capacity would only result in a small reduction in the river's level.
(the water flow; exceeds; the bank elevation and the river's predetermined flood stage) (even pumping at maximum capacity; would only result; in a small reduction in the river's level; T:Once the water flow exceeds the bank elevation and the river's predetermined flood stage)
the water flow even pumping at maximum capacity
exceeds would only result
the bank elevation and the river's predetermined flood stage
in a small reduction in the river's level T:Once the water flow exceeds the bank elevation and the river's predetermined flood stage