南方水库热分层消亡时期水体混合特征及其驱动机制  

Characteristics and mechanism of water mixing structure during the extinction of thermal stratification in southern reservoirs

作　　者：王璨 李一平[1,2] 李聂贵[3] 郭晋川 朱雅 吴卫熊 魏尧 陈宇 Wang Can;Li Yiping;Li Niegui;Guo Jinchuan;Zhu Ya;Wu Weixiong;Wei Yao;&Chen Yu(College of Environment,Hohai University,Nanjing 210098,P.R.China;Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes,Ministry of Education,Hohai University,Nanjing 210098,P.R.China;Nanjing Research Institute of Hydrology and Water Conservation Automation,Ministry of Water Resources,Nanjing 210012,P.R.China;Guangxi Water Conservancy Science Research Institute,Nanning 530023,P.R.China)

机构地区：[1]河海大学环境学院,南京210098 [2]河海大学浅水湖泊综合治理与资源开发教育部重点实验室,南京210098 [3]水利部南京水利水文自动化研究所,南京210012 [4]广西壮族自治区水利科学研究院,南宁530023

出　　处：《湖泊科学》2023年第5期1613-1622,共10页Journal of Lake Sciences

基　　金：国家自然科学基金项目(52039003);广西科技计划项目(桂科AB20297017);中央高校建设世界一流大学(学科)和特色发展引导专项资金联合资助。

摘　　要：稳定分层的深水水库常在冬季发生“翻库”现象,继而导致水库的整体水质下降,影响饮用水安全问题。为探究南方水库热分层消亡时期水体混合特征,在冬季2019年11月—2020年2月对南宁市天雹水库水体理化指标开展长序列原位监测,并结合水体垂直扩散系数,分时期(热分层期、减弱期、完全混合期、形成期)刻画水库热分层消亡全过程中水温T、溶解氧DO的剖面变化特征,探讨了气象因子(气温、太阳辐射、风速等)与水动力因子(水体垂直扩散系数K_(z))对水体理化指标的影响。结果显示:桉树人工林区水库热分层消亡期温度分层与溶解氧分层变化不同步,溶解氧分层的破坏较水温分层的破坏出现滞后,其结构失稳是气温及太阳辐射共同作用的结果;期间水体垂直扩散系数变化范围0.16~380.36 m^(2)/d,均值为30.46 m^(2)/d,表层K_(z)变化的主要控制因子为气温变化,且较T及DO而言,表层K_(z)对气温的变化更加敏感(R_(K_(z))=-0.44,R_(T)=0.25,R_(DO)=0.25,P<0.01),底层K_(z)的变化与水体混合程度变化一致,能够更准确地表征水体垂向混合情况;水体垂向T、DO、lgK_(z)分布具有时间异质性,热分层期及半混合时期lgK_(z)与T及DO均呈现显著的正相关(R_(T)=0.60、P_(DO)=0.76,P<0.01),而在水体完全混合后,K_(z)与T呈现负相关(R_(T)=-0.19,P<0.01),与DO不存在相关关系(R_(DO)=0.04,P>0.05)。热分层消亡为水质恶化提供了环境条件,因此在水库监控管理中,应当着重关注冬季气象因子的变化,并加以防范。Deep reservoirs with stable stratification often‘turn over’in winter,leading to a decline in overall water quality and affecting the safety of drinking water.To explore the mixing characteristics of water bodies during the thermal stratification period in southern reservoirs,long-term in-situ monitoring of physical and chemical indices of Tianbao Reservoir in Nanning was conducted from November 2019 to February 2020 during the thermal stratification fading in winter.Combined with the vertical diffusion coefficient of water,the variation characteristics of water temperature(T)and dissolved oxygen(DO)in the whole process of thermal stratification of the reservoir were described by stages(thermal stratification,weakening,complete mixing and formation),and the influences of meteorological factors(air temperature,solar radiation,wind speed,etc.)and hydrodynamic factors(vertical diffusion coefficient K_(z))on the physical and chemical indices of water were discussed.The results showed that the temperature stratification and the dissolved oxygen stratification of the reservoirs were out of sync during the extinction of the thermal stratification,and the destruction of the dissolved oxygen stratification lags behind that of the water temperature stratification,and its structural instability was the result of the combined action of air temperature and solar radiation.During this period,the vertical diffusion coefficient of the water body varied from 0.16 to 380.36 m^(2)/d,with an average value of 30.46 m^(2)/d.The main controlling factor of surface K_(z) change was air temperature change,and surface K_(z) was more sensitive to air temperature change than T and DO(RK_(z)=-0.44,R T=0.25,R_(DO)=0.25,P<0.01).The change in bottom K_(z) was consistent with the change in water mixing,which could more accurately characterize the vertical mixing of water.The vertical distribution of T,DO and lg K_(z) in the water body was temporally heterogeneous.The lgK_(z) was positively correlated with T and DO during thermal stratification

关 键 词：热分层 水温 溶解氧 垂直扩散系数 

分 类 号：X524[环境科学与工程—环境工程]