摘要
以岩口水库小流域为研究对象,通过监测2019年和2020年2次台风降水过程中入库河流氮磷通量变化,解析了极端降水事件对入库河流及下游库区污染负荷的影响,并评估极端降水条件下外源输入对库区水质污染的贡献。结果表明,降水历时和强度存在明显差异的两场暴雨全过程均可划分为4个典型阶段,即局部产流期、全流域产流期、水量消退期和流域恢复期。其中以全流域产流期(第Ⅱ阶段)污染负荷最重,输送了整个阶段50%以上的总磷负荷,且污染负荷的增长倍数与降水强度呈显著正相关。与降水前相比,台风“利奇马”和“黑格比”两场降水过程对下游岩口水库的入库总氮污染负荷分别增加了880 kg和419 kg,总磷污染负荷分别增加了110 kg和23 kg,而且增加的总氮以溶解态为主,总磷以颗粒态为主,说明地表径流冲刷导致河流中汇入了大量的面源污染负荷。本研究证实了极端降水事件,尤其是全流域产流阶段的降水会显著加剧流域面源对下游库区的污染贡献,建议采取合理的滞蓄、沉淀和净化等策略对地表径流污染负荷进行削减以降低下游库区水质污染风险。
The influence process of extreme rainfall events on the water pollution load of upstream rivers and downstream reservoirs in the basin was analyzed,and the contribution of external input to water pollution in the reservoir area under extreme rainfall conditions was evaluated,withthe small watershed of Yankou reservoir as the research object,by monitoring the changes of nitrogen and phosphorus flux of river entering the reservoir during two typhoon rainstorms in 2019 and 2020.The results showed that the whole process of the two rainstorms with obvious differences in rainfall duration and intensity can be divided into four typical stages:local runoff generation period,whole watershed runoff generation period,water volume regression period and watershed restoration period.The heaviest pollution load ocuured in the whole watershed runoff generation period(stage II).More than 50% of the total phosphorus load in the whole stage was transported in stage II and the increasing multiple of the pollution load was significantly correlated with the rainfall intensity.During the two rainstorms of LQM and HGB,TN load of Yankou reservoir increased by 880 kg and 419 kg,TP load increased by 109 kg and 23 kg respectively,compared with that before the rainfalls.It was showed that surface runoff erosion leaded to a large amount of non-point source pollution load into the river,since the increased total nitrogen was mainly dissolved,while the increased total phosphorus was mainly granular.The results of this study proved that extreme rainfall events,especially in the whole watershed runoff generation period,significantly aggravated the pollution contribution of non-point sources to the downstream reservoir area.Therefore,it is suggested to adopt reasonable strategies such as detention,sedimentation and purification to reduce the pollution load of surface runoff in order to reduce the risk of water pollution in the downstream reservoir area.
作者
王亚博
李慧莉
张洪刚
何怡
焦茹媛
刘凡
张宝
杨敏
WANG Yabo;LI Huili;ZHANG Honggang;HE Yi;JIAO Ruyuan;LIU Fan;ZHANG Bao;YANG Min(School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Research Center for EcoEnvironmental Sciences,Chinese Academy of Sciences,Beijing 100085,China;Yangtze River Delta Research Center for Eco-Environmental Sciences,Yiwu 322000,China;School of Environmental Studies,China University of Geosciences,Wuhan,430078,China)
出处
《环境工程学报》
CAS
CSCD
北大核心
2022年第6期2061-2072,共12页
Chinese Journal of Environmental Engineering
基金
国家自然科学基金资助项目(41877473)
国家重点研发计划(2021YFC3200904)。
关键词
极端降水
岩口水库
外源负荷
氮磷通量
降水径流
extreme rainfall
Yankou Reservoir
exogenous load
nitrogen and phosphorus flux
rainfall runoff
