平原型水库水体热分层的水质响应特征与水质改善成效

针对平原型水库热分层特征及其对水质的影响问题,采用CE-QUAL-W2模型建立了立面二维水温模型,模拟了2018年全年的水温变化特征,三个率定断面的绝对平均误差分别为0.53℃、0.35℃和0.14℃。基于模拟结果和监测数据,分析了水库热分层的季节性变化及水质响应特征。在轴流泵混合曝气技术的基础上提出了一种移动式扬水器用以增加水库底层DO浓度,基于监测数据初步分析了移动式扬水器对垂向水质的改善效果。结果表明:水库全年呈现单循环混合模式(5月-11月为分层期,12月-4月为混合期),夏季形成稳定的热分层结构,底层形成厚度约为8m的缺氧区(DO浓度低于2mg/L);厌氧环境下底层污染物(铁、锰、总氮、总磷、COD、氨氮等)的释放量远大于表层和中层,底层水质较差;移动式扬水器能够有效提高底层DO含量,弱化热分层结构(工作中心的DO浓度由0.2mg/L提高至0.8mg/L,温跃层厚度减少了4m)。     

西安黑河金盆水库季节性热分层的水质响应特征

以西安市金盆水库为对象,通过对水温、水化学及水生生物因子的连续监测,初步探明其动态水体分层过程与季节性水质迁移分布的内在相关性.研究表明:水库于每年3—12月间形成并保持热分层状态,水温梯度的稳定存在有效限制了垂向水层间氧的传质交换,加速库底向厌氧状态过渡,滞水层溶解氧(DO)平均浓度随时间呈明显线性衰减趋势,水层呼吸速率高达0.0356~0.0372mg/(L·d)(O2);缺氧/厌氧环境下,沉积物中N、P、Fe等大量释放并向上覆水扩散,底层水质污染加剧.同温混合期后(1—2月),分层结构破坏,全库处于好氧(DO大于8mg/L)、微碱性(pH为7.1~7.3)状态,垂向水质分层异质特征消失.监测期间,水库湖泊区稳态叶绿素a含量(基于Lois Elle稳态假设前提)随混合深度增大而降低,两者存在显著指数负相关.热分层效应的稳定存在是加速金盆水库富营养化进程的重要因素;而其周期性结构失稳所带来的水质突发性污染风险将伴随水库运行时间的延长而上升.     

北方河道峡谷型水库季节性分层的水质响应特征

以西安市J-P水库为研究对象,通过水温、水化学及水生生物因子的连续监测,初步探明了其动态水体分层过程与季节性水质分布变化的内在相关性。研究表明：水库于每年3~12月间形成并保持热分层状态,温度梯度的存在有效限制了垂向水层间的氧传质交换,加速库底向厌氧状态过渡,滞水层中DO平均浓度随时间呈明显线性趋势衰减,水层耗氧呼吸速率高达0.0356~0.0372O2 mg/(L•d);缺氧/厌氧环境下,沉积物中N、P、Fe等大量释放并向上覆水体扩散,底层水质污染加剧。进入同温混合期后（1~2月）,热分层结构破坏,全库处于好氧（DO>8mg/L）、微碱性（pH:7.1~7.3）状态,垂向水质趋于均一。监测期间,水库湖泊区稳态叶绿素a含量（基于Loiselle稳态假设前提）随混合深度的增大而降低,两者存在较强的指数负相关性（y=4.2664e-0.0323x,R2=0.8036）。热分层效应的稳定存在是加剧J-P水库富营养化的重要因素;而其周期性结构失稳所带来的水质突发性污染的风险将伴随水库运行时间的增长而上升。     

基于分层监测的水库水质时空变化特征研究

为解决以往水质监测数据多是针对表层水体采样,难以完整的反映水库水质状况的问题,本文以碧流河水库为研究对象,根据其水文及地形条件从水库上游至坝前依次选取六个监测断面,采用分层监测的方式对水库水质进行监测,利用GIS地统计学方法和图片展示功能对碧流河水库的温度、溶解氧、总氮及总磷的垂向分层分布状态进行分析,直观的展示出动态水位下的水库垂向深度变化及其相应的水质属性。结果表明水库总氮呈现均匀混合状态;水库总磷呈现汛期大,汛后小,冬季最低的变化特征,平面分布上呈现水力推移的特征,随着水力方向逐渐减少,垂向上则无明显分层现象。     

基于水质现场监测参数的于桥水库水体分层特征初步研究

于桥水库是跨流域供水的水库,研究各项水体现场监测参数随水深变化规律,结果表明:于桥水库表层(0~4 m)是水体交换活动频繁的区域,水下(4~10 m)为于桥水库的温跃层,水下(10 m)为下层水体。在温跃层,水温、p H值、电导率、溶解氧等指标发生了剧烈的变化,氧化还原电位受水体深度影响较明显,叶绿素a受水体深度影响也较明显。     

大型水库三维水质模型研究

针对大型水库水质要素分布呈现明显三维效应的特点,建立了一种考虑温度分层影响的DO,CODCr,TP,TN三维水质预测模型。采用二滩鱼感鱼河支库原型观测资料对模型进行验证,并分析了模型误差产生的原因及模型的适用性。分析结果表明,所建模型可以用于对DO,CODCr,TP,TN等水质要素的数值模拟,模拟成果可为大型水库修建的环境影响评价提供科学依据。将该模型应用于某在建大型水库,成功模拟预测了该水库水质要素的三维分布特性。     

寒旱区某浅型水库热分层特征及供水影响

文章连续监测不同深度水质变化趋势,阐明寒旱区某浅型水库热分层特征。在夏季水库出现热分层现象,水深较深的库区形成活性反应带,底层溶解氧达到缺氧区阈值2mg/L以下,铁和锰超标,水库内源污染是形成活性反应带的重要因素。描述了水生动植物代谢活动、动植物残体及排泄物、沉积物带来的内源污染因素,水体循环较慢是出现热分层的重要条件。提出了浅型水库热分层现象对供水安全的影响,为保证供水安全提供了科学依据和防治措施。     

洋河水库热成层对水质的影响

洋河水库在７ 月末到９ 月初之间存在明显热成层，造成表、底层水质差异，“水华”严重时，表层ｐ Ｈ 高达９１６ ，溶解氧达１２４８ｍｇ／ Ｌ，亚硝酸盐氮达０１３２ ｍｇ／ Ｌ，藻类细胞密度达６２３ 万个／ Ｌ，均显著高于底层水体。对水质分层的原因和部分水质指标的相互影响进行了初步分析，并探讨了相应的取水对策。     

南方某水库底层溶解氧分布特征及低氧成因分析

以南方某水库为例,通过2013年4月至2014年3月的监测数据研究底层溶解氧(bottom dissolved oxygen,BDO)和底层水温(bottom temperature,BT)、p H值、电导率、浊度(TU)、TP、TN、COD、总有机碳(TOC)、Chl-a间的关系,以阐明该水库BDO的时空分布特征及低氧成因。结果表明,BDO春、夏季浓度低,秋、冬季(枯水期)浓度较高,进水口附近的DO浓度普遍高于库中、库心;低氧现象主要发生在夏季(5—8月);水越深、水温越低,BDO下降趋势显著(P0.05);浊度、TOC与BDO为正相关关系。BDO与叶绿素a呈现显著正相关,在底层浮游植物中,蓝藻门占绝对优势,BDO浓度与蓝藻的垂直迁移有关。表明水库BDO在时间上的变化趋势受温度的影响,而空间上的变化受到水动力的影响,低氧现象的发生受到水体垂直密度分层的影响。     

Modelling approach for characterizing thermal stratification and assessing water quality for a large tropical reservoir

The dynamics of water temperature, dissolved oxygen and total dissolved solids concentrations in Aguamilpa Reservoir was analysed by considering horizontal and water column variations. The reservoir model, CE‐QUAL‐W2, was used to simulate the temporal variations calibrated with data gathered every 2 months from June 2008 to June 2009. Temperature depth profiles indicated a typical asymmetry of reservoirs exhibiting a large stratification in the lower part near the dam. Dissolved oxygen concentration profiles exhibited some degree of anoxia in the bottom water during the rainy season (May through October). This is most likely due to decomposition vegetation and organic matter via soil erosion and run‐off from the basin accumulating at the bottom of the reservoir. The reservoir stratification is clearly seasonal, occurring during the rainy season, especially in the lowest reservoir zones. The CE‐QUAL‐W2 model results provided a comprehensive understanding of the temporal behaviour of the study variables during the modelling study period. Application of this water quality model is directed to water resource managers to help them better understand the dynamics of physico‐chemical processes, and how they vary temporally and spatially in the reservoir, and to propose the best management practices for preserving or improving the water quality of the system.     

Water quality characteristics of two reservoir lakes in eastern Connecticut, USA

The Mansfield Hollow Lake (MHL) and Willimantic Reservoir (WR) are two reservoirs located in eastern Connecticut in the north‐eastern USA. The MHL was constructed by the US Army Corps of Engineers in 1952, being primarily fed by the Fenton, Mount Hope and Natchaug Rivers. The WR lies downstream from the Mansfield Hollow Dam. The physical and chemical characteristics of MHL, WR, and the three streams discharging into them were intensively evaluated during four sampling quarters in 2001 and 2002. This study focused on possible sources of eutrophication, and occurrence of trace amounts of selected priority pollutants, in the sediments and waters of MHL and WR. Analytical results for total dissolved nitrogen and phosphorus and chlorophyll‐a indicated that, in terms of eutrophication status, the waterbodies can be classified as mesotrophic. Comparison of the analytical results in this study to historical limnological data reported for lakes in southern New England and eastern Connecticut indicates that the median levels of total nitrogen, total phosphorus, dissolved inorganic carbon, calcium, magnesium, and iron measured in this study were higher than previously reported median values.     

河道型深水库的温度分层模拟

本文建立了计入浮力影响的立面二维水温模型，用二滩的实测资料对模型进行了验证，再将该模型应用于另一待建的河道式深水库，精细地模拟出斜温层的形成、发展和消失，分析了水库全年的温度分层结构。     

Statistical assessment of water quality seasonality in large tropical reservoirs

A statistical assessment was used to assess if a tropical reservoir had reached a stable condition, permitting the use of water quality models to predict the water quality dynamics of a water system under different climatic or management scenarios. This approach was applied to Aguamilpa Reservoir in western Mexico, one of the largest tropical reservoirs in the world. Water quality data collected by the National Water Commission, and hydrological and climatic data from the Federal Electricity Commission from the period of January 2000 to December 2007 served as the data base. Time‐series analysis identified three distinct homogeneous seasonal groups: (i) warm dry season, (ii) rainy season and (iii) cold dry season. The seasonal responses of water quality parameters (temperature, electrical conductivity, total suspended solids concentration, biochemical oxygen demand and total coliforms) were demonstrated through analysis of variance of the principal components.     

分层型水库取水水温量纲分析及其影响因素研究

水温分层作为影响库区水生生态系统的重要因素逐渐成为研究热点。影响下泄水温的主要因素包括:坝前水温梯度、取水水头、取水流量、取水口宽度、温跃层厚度、重力加速度等。通过量纲分析法,基于π定理尝试建立了溢流式分层取水下泄水温估算模型。采用SAS 9.3统计软件对实验数据进行了回归分析,提出了下泄水温估算方程,相关系数达到95.6%。研究结果表明,水温梯度项为下泄水温估算的最主要因素,其次为取水水头项,最后为流量项;随着坝前水温温跃层强度增大,下泄水温升高,且强度越大,对下泄水温的影响越显著;下泄水温随取水水头的增加而降低,下泄水温降低幅度明显小于取水水头变幅;当取水流量逐渐增大时,下泄水温逐渐升高,但取水流量大于临界值时,下泄水温转而表现出缓慢下降趋势;在本文研究范围内,估算方程可以用于较好地预测下泄水温,预测结果与实验数据的相关系数为99.4%。     

大型水库功能演变对水库水质的影响——以河南省某大型水库为例

水库水质污染是水库利用过程中比较普遍发生的现象,与水库功能演变直接相关。河南省某大型水库目前集防洪、灌溉、城市供水、旅游、养殖、发电、航运等多种功能于一体,在区域社会发展中作用重大。以该水库为例,运用相关分析法,探讨了该水库自1997年以来的水质波动状况与其功能演变之间的关系,发现旅游经济、养殖业经济发展与水库总氮、总磷、石油类等水质指标之间存在比较显著的正相关关系,表明该水库发展旅游、养殖功能存在环境容量限制性,对大型水库功能调整必须注意其生态环境承载能力。