金沙江下游梯级水库夏冬季垂向水体理化特征研究  

Study on vertical physicochemical characteristics of water of cascade reservoirs in lower reaches of Jinsha River in summer and winter

作　　者：管义伟 李银波 陈露欣 肖艳[1] 李哲[1] 鲁伦慧[1] GUAN Yiwei;LI Yinbo;CHEN Luxin;XIAO Yan;LI Zhe;LU Lunhui(Chongqing Institute of Green and Intelligent Technology,Chinese Academy of Sciences,Chongqing 400714,China)

机构地区：[1]中国科学院重庆绿色智能技术研究院,重庆400714

出　　处：《人民长江》2024年第12期54-63,共10页Yangtze River

基　　金：国家自然科学基金项目(U2340222,51979262);中国长江三峡集团有限公司科研项目(202103493,202403005);中国科学院西部之光“西部青年学者”计划项目;重庆交通大学研究生科研创新项目(62789093)。

摘　　要：大坝建设与水库蓄水明显改变了河流的水文条件,使得坝前区域流速减缓、水位显著升高,进而影响库区物质循环模式。然而,目前关于金沙江下游梯级水库调度影响下的垂向水体理化特征变化情况仍不清晰。为此,2022年1月(冬季)和7月份(夏季)分别对乌东德、溪洛渡、向家坝3座水库坝前垂向水体进行分层采样,分析坝前垂向梯度下水温和溶解氧浓度的分布特征,并探究不同时期垂向光、热、氧特性差异的成因。结果表明:①垂向光、热、氧特性表现出明显的季节性特征,而入库和出库流量是决定梯级水库中垂向分层特性的关键因素。在夏季,垂向水温梯度变化不明显,3座水库均未形成稳定的温跃层,且库区水体垂向掺混均匀,混合层深度与水深相当;冬季水库中出现了稳定的热力分层,但受水位波动和库区水体交换的影响,主要集中在表层0~10 m水体中。此外,梯级水库中热分层稳定指数(RWCS/H)则是夏季要远大于冬季。溶解氧浓度受水温和浮游植物共同影响,在夏季表层水体中出现实测值要远高于理论饱和值的现象,并伴有氧跃层的出现。②相关性分析结果显示,夏季叶绿素a浓度与水温、溶解氧、pH、电导率、总氮和光照条件(水体透明度和真光层深度)显著正相关,冬季叶绿素a浓度则与水体透明度显著正相关,表明库区水温适宜,且光照和营养盐充足的条件下,会显著促进浮游植物的生长,进一步增加水体中饱和溶解氧浓度。因此,夏季溶解氧浓度和氧跃层厚度要明显大于冬季。冬季的真光层深度显著大于夏季,通过相关性分析发现,真光层深度主要受表层水体透明度影响,与上游来水中的泥沙含量和暴雨径流密切相关。研究成果可为水库生态的适应性调度提供参考。Damming and reservoir impoundment significantly alter riverine hydrological conditions,leading to reduced flow velocity and elevated water levels in upstream areas,subsequently influencing material cycling patterns in reservoir zones.However,the vertical variations in physicochemical characteristics of water bodies under cascade reservoir operation in the lower Jinsha River remain poorly understood.This study investigated these variations through stratified sampling of vertical water bodies at the front of three reservoirs(Wudongde,Xiluodu,and Xiangjiaba)during winter(January)and summer(July)2022.We analyzed the distribution patterns of water temperature and dissolved oxygen concentrations along vertical gradients,and explored the driving mechanism of seasonal differences in vertical light,thermal,and oxygen characteristics.The results revealed two key findings:①Vertical light,thermal,and oxygen characteristics exhibited distinct seasonal patterns,primarily controlled by reservoir inflow and outflow rates.The waters didn′t show obvious vertical temperature gradients in summer,and stable thermocline formations weren′t formed in all three reservoirs.The water was mixed evenly in the vertical direction,and the depth of mixing lay was almost equivalent to the whole water depth.In winter,the water exhibited stable thermal stratification predominantly observed in surface waters(0~10 m),influenced by water level fluctuations and reservoir flow exchange.The thermal stratification stability index(RWCS/H)was substantially higher in summer compared to winter.Surface waters during summer showed dissolved oxygen concentrations exceeding theoretical saturation levels,accompanied by oxycline formation,reflecting the combined influence of water temperature and phytoplankton activity.②The concentration of chlorophyll-a was found to be significantly positively correlated with water temperature,dissolved oxygen,pH,conductivity,total nitrogen,and light conditions(water transparency and euphotic depth)in the summer,but only w

关 键 词：水体理化特征 分层特性 热分层稳定指数 真光层深度 调度运行 梯级水库 金沙江下游 

分 类 号：P333[天文地球—水文科学] TV697.21[水利工程—水文学及水资源]