Which term describes the flow of water in a river channel that is below the bankfull stage?

The term that describes the flow of water in a river channel that is below the bankfull stage is low flow. At low flow conditions, the water levels are relatively low compared to the potential maximum capacity of the river channel, which is indicated by the bankfull stage. This situation typically occurs during periods of reduced rainfall or where there is significant water withdrawal for agricultural, industrial, or municipal uses.

In contrast to low flow, maximum discharge refers to the highest amount of water that the river can carry, which is not applicable when considering flow below the bankfull level. Normal flow generally refers to typical flow conditions, which could be any flow that is neither extremely low nor high but doesn't specifically indicate conditions below the bankfull stage. Flash flow describes a rapid rise in water level usually associated with heavy rainfall or sudden release from reservoirs, which is again outside the context of steady or lower water levels. Therefore, low flow accurately captures the condition of water flow that is consistently below the capacity of the river banks.