Drainage Water Reuse Through a Baffled Constructed Wetland System: A Pilot Study in the Harran Plain, Türkiye

ABSTRACT The reuse of agricultural drainage water requires low‐cost pretreatment for sediments and salts. This study developed a pilot‐scale horizontal surface‐flow baffled constructed wetland for passive pretreatment of agricultural drainage water. Unlike conventionally constructed wetlands, the system used a baffled hydraulic configuration to regulate flow behaviour, reduce velocity and enhance sediment retention. Before construction, alternative baffle layouts were optimised with Flow‐3D; the final design was selected using velocity distribution, low‐velocity sedimentation zones and reduced velocities between baffles. The selected configuration comprised 10 gravel‐filled gabion baffles installed at 60° with 2.90 m spacing. It was implemented in a drainage channel in the semiarid Harran Plain, Türkiye, receiving water from irrigated cotton, wheat and corn parcels. Channel‐entry turbidity, suspended solids (SS), total solid matter (TSM) and electrical conductivity (EC) averaged 73.5 ± 133.5 NTU, 47.5 ± 92.4 mg L −1 , 1094.6 ± 516.6 mg L −1 and 1362.1 ± 623.7 μS cm −1 , respectively. Overall turbidity and SS removal were 73% and 90%, respectively. TSM and EC were not clearly reduced, reflecting limited removal of dissolved solids and salts. The system may support sediment control and irrigation reuse planning as passive pretreatment; separate treatment is required for salinity reduction.