Agricultural drainage ditches play an important role in removing surplus water; however, these can also potentially act as major conduits of agricultural nonpoint source pollutants, including sediment, nitrogen, and phosphorus. A supplementary hybrid system to limit such pollution was developed in this study; this consists of biodegradable fiber check dams, used in combination with a synthetic polymer (Polyacrylamide, PAM). An open channel experiment was conducted to optimize the design of the hybrid system, taking into account a variety of physical and hydraulic conditions. Subsequent field application of the hybrid system improved runoff water quality, such as 10.0% to 98.3% reduction for suspended solids, 25.2% to 98.4% reduction for turbidity, 21.1% to 91.1% increase for BOD, 19.2% to 75.4% increase for COD, 21.0% to 73.3% reduction for T-N, 5.9% to 91.2% reduction for T-P and 35.7% to 97.6% reduction for fecal coliforms. This clearly showed that this hybrid system could play a significant role in supplementing conventional best management practices.
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