impact of control gates on long-term sedimentation patterns in tidal canals: a field study

Sedimentation is one of the major challenges in tidal water supply canals used for shrimp farming. progressive deposition reduces canal depth and cross-sectional area, thereby limiting water exchange, increasing maintenance costs, and threatening the sustainability of aquaculture systems. this study investigates the long-term influence of control gates on sedimentation dynamics in the north tiyab shrimp farm, located on the southern coast of iran. two tidal canals were examined: canal c2, equipped with a control structure at its intake, and canal c3, which lacks such a structure. field surveys included crosssectional measurements at 300 m intervals and longitudinal profiles at multiple points along the canals. additional tidal observations and flow conditions were also recorded. the results show that canal c2 experiences relatively uniform deposition along its length, with sediment accumulation observed even at the intake where scouring was expected. this is attributed to the hydraulic effects of the control gate and subsequent dredging activities. in contrast, canal c3 exhibits stronger variability, including significant scouring near the entrance followed by progressive downstream deposition, intensified by pumping activities and inflow from the connecting canal (cmc). overall, the findings highlight that control gates can both mitigate and exacerbate sedimentation, depending on their design and operation. long-term monitoring is therefore essential for optimizing canal management, reducing dredging costs, and improving the efficiency of shrimp farming systems.