title: Impact of flood damage on pollutant removal efficiencies of a subtropical urban constructed wetland.
abstract: Typhoons and hurricanes in subtropical/tropical regions can induce significant environmental changes (e.g., mass flooding and inundations). However, the damage to the pollutant removal efficiencies of constructed wetlands brought about by these natural disturbances has been neglected in major studies conducted in temperate climates. Therefore, this study compares the pollutant removal performance of a constructed wetland in the Danshui River Basin, before and after the system was inundated with flooding from Typhoon Krosa in 2007. The pollutant removal performance of the free water surface (FWS) constructed wetland was investigated monthly from September 2006 to April 2008. Results of the study demonstrated that this FWS wetland effectively removed 64.3% BOD, 98.9% NH(4)-N, and 39.5% Total-P before Typhoon Krosa. However, the extensive flooding caused by Typhoon Krosa swept over most of the aboveground plant community and deposited the sediment onto the bottom of each compartment. Subsequently, reduced pollutant removal efficiencies were observed. Only 37.7% BOD, 35.1% NH(4)-N, and 31.8% Total-P were removed after this event, although the flow regime was immediately restored. Comparing the water quality data for the FWS wetland before and after Typhoon Krosa revealed the immediate, quantitative damage to the pollutant removal performance caused by the typhoon's inundation. Consequently, a high-flow bypass and additional preventive measures would protect any constructed wetland in areas subject to typhoons.
authors.affiliation: School of Forest and Resources Conservation, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan, ROC.
authors.forename: Chun-Han
authors.initials: CH
authors.lastname: Ko
authors.forename: Fang-Chih
authors.initials: FC
authors.lastname: Chang
authors.forename: Tsai-Ming
authors.initials: TM
authors.lastname: Lee
authors.forename: Pen-Yuan
authors.initials: PY
authors.lastname: Chen
authors.forename: Hsin-Hsiung
authors.initials: HH
authors.lastname: Chen
authors.forename: Hwey-Lien
authors.initials: HL
authors.lastname: Hsieh
authors.forename: Chung-Yu
authors.initials: CY
authors.lastname: Guan
mesh_terms: D000641:Ammonia / Q000032:analysis; D002947:Cities; D055867:Cyclonic Storms; D004190:Disasters; D004526:Efficiency; D052918:Environmental Restoration and Remediation; D055868:Floods; D009584:Nitrogen / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D014329:Tropical Climate; D014873:Water Pollutants / Q000032:analysis*; D053833:Wetlands
chemical_list: D014873:Water Pollutants; D010758:Phosphorus; D000641:Ammonia; D009584:Nitrogen; D010100:Oxygen