A submerged weir is preferable to a normal weir under several conditions:

High Flow Conditions: When flow rates are very high, causing the normal weir’s crest to be submerged, a submerged weir is designed to handle such conditions more effectively.

Variable Flow Control : It accommodates fluctuating flow rates better, maintaining effective water diversion even when flow levels change significantly.

Flow Measurement  & Its Control: Provides more reliable measurements in varying water levels, as it functions effectively even when partially or fully submerged.

Erosion Control in Channel Bed: Helps reduce downstream erosion .

Sedimentation Management or control: Handles high sediment rates better, minimizing sediment build-up compared to a normal weir.