Comprehensive nonpoint source pollution models for a free-range chicken farm in a rural watershed in Taiwan

▶ The main objective of this study is to quantify the impact of FRCF on water quality parameters. ▶ A distributed rainfall-runoff model and water quality models were used. Their relevant parameters were then calibrated and verified based on collected precipitation records, along with runoff and water quality data. ▶ Raising cycle of the target chicken farm, located at Longchi Township in southern Taiwan, was required for the estimation of NPS loads in the case study. ▶ Unit pollution loads per raising cycle during the rainfall period were calculated. ▶ The simulated results indicate that the higher the rainfall is, the higher the unit pollution load per raising cycle will be; confirming that the NPS pollution is highly dependent on the change of seasons.▶ The finding clearly indicates that the FRCF exerts high potential threat to reservoir.