Designing hydraulic structures requires careful consideration of local scouring downstream.
This study investigated the performance of trapezoidal labyrinth weirs in controlling flow and
mitigating scour in straight channels through physical model experiments. Sixty configurations were
examined, using weir apex angles of 20◦, 45◦, 60◦, and 80◦, heights of 30 cm, 35 cm, and 40 cm,
and flow rates of 50–200 L/s. A linear weir served as a reference. The results showed that the 60◦
apex angle consistently outperformed other configurations, reducing scour depth by up to 41% and
scour length by up to 50% compared to the linear weir. It also decreased deposition depth by 40%
and length by 50%. Lowering weir height from 40 cm to 30 cm led to reductions of 35% in scour
depth and 40% in scour length at low discharges. These improvements remained significant even
at higher flow rates, with a 29% reduction in scour depth and 25% in scour length at 200 L/s. This
study provides evidence-based recommendations for optimizing labyrinth weir designs to define the
relationship between hydraulic efficiency and erosion control. It offers valuable insights into weir
geometry, flow conditions, and the resulting scour and deposition patterns. These findings contribute
to the optimization of labyrinth weir designs to minimize downstream bed configurations. The tests
were conducted under limited flow conditions.