Efficiency and mechanism of pretreatment on water supply in reservoirs of Yellow River by subsurface constructed wetlands

In order to improve the source water quality of drinking water and mitigate the load of drinking water treatment plant, a pilot test was conducted with integrated horizontal flow constructed wetlands to pretreat the water supply in the reservoirs of Yellow River. Resuhs show that under the hydraulic loading rate of 4 m^3/（ m^2 · d）, the average removal rates of chemical oxygen demand （COD）, total nitrogen （TN）, ammonium nitrogen （ NH4 ^＋ - N）, nitrate nitrogen （ NO3 ^- - N）, nitrite - nitrogen （ NO2^ - - N） and total phosphorus （TP） in the horizontal flow constructed wetlands are 49. 68% , 53.01%, 48.48%, 53.61% , 62. 57% and 49. 56%, re- spectively. The study on purifying mechanism of the constructed wetlands indicates that the disposal of contamination by subsurface wetlands is the combined actions of physical chemistry, plants and microorganism.

Equilibrium sediment transport in lower Yellow River during later sediment-retaining period of Xiaolangdi Reservoir

The Xiaolangdi Reservoir has entered the later sediment-retaining period, and new sediment transport phenomena and channel re-estab- lishing behaviors are appearing. A physical model test was used to forecast the scouring and silting trends of the lower Yellow River. Based on water and sediment data from the lower Yellow River during the period from 1960 to 2012, and using a statistical method, this paper analyzed the sediment transport in sediment-laden flows with different discharges and sediment concentrations in the lower Yellow River. The results show that rational water-sediment regulation is necessary to avoid silting in the later sediment-retaining period. The combination of 3 000 m^3/s 〈 Q 〈 4 000 m^3/s and 20 kg/m^3 〈 S 〈 60 kg/m^3 （where Q is the discharge and S is the sediment concentration） at the Huayuankou section is considered an optimal combination for equilibrium sediment transport in the lower Yellow River over a long period of time.

Characteristics and influencing factors of greenhouse gas emissions from reservoirs in the Yellow River Basin:A Meta-analysis

Reservoir construction and operation profoundly alter the hydrological,hydrodynamic,and carbon and nitrogen cycling processes of rivers.However,current research still lacks a systematic understanding of the characteristics of greenhouse gas(GHG)emissions from reservoirs in arid/semi-arid regions.This study integrates existing monitoring data to discuss the characteristics of GHG emissions from reservoirs in the Yellow River Basin and illustrate the controlling factors and underlying mechanism of these processes.The results indicate that while CO_(2) emission flux from reservoirs is lower than that from river channels,the emission fluxes of CH_(4) and N_(2)O are 1.9 times and 10 times those from rivers,respectively,indicating that the emission of GHG with stronger radiative effect is significantly enhanced in reservoirs.Compared to the reservoirs in humid climates(e.g.,the Three Gorges Reservoir),reservoirs in the Yellow River Basin exhibit relatively lower emissions of CO_(2) and CH_4 due to lower organic matter concentrations,but significantly higher N_(2)O emissions due to higher nitrogen loads.Monte Carlo simulations for 237 reservoirs in the Yellow River Basin showed that total emission of the three GHGs is 3.05 Tg CO_(2)-eq yr^(-1),accounting for 0.39% of the total emission from global reservoirs and lower than the area percentage of the basin(0.53%).This study has important implications on revealing the GHG emission characteristics and control mechanisms of reservoirs in arid/semi-arid regions.

Water renewal time of the Yellow River mainstream based on reservoir action

This note analyzes the change in water renewal time characteristics based on res- ervoir action and then establishes calculation models for the water renewal time in the Yellow River mainstream. The results indicate that the amount of renewable water with reservoir action can meet the annual water demand and that water flows naturally at the Lijin station near estuary. Initial storage dynamics is an important factor in water resource renewable capacity at a certain time, and rational reservoir action can promote sustainable water re- source utilization. When the initial storages in the Longyang Gorge reservoir are 9,343 and 5.343 billion m3, the water renewal times are 28 and 33.9 d, respectively. Flow stoppage appears in April and May.

Adjustment in the main-channel geometry of the lower Yellow River before and after the operation of the Xiaolangdi Reservoir from 1986 to 2015

Based on the measured discharge,sediment load,and cross-sectional data from 1986 to 2015 for the lower Yellow River,changes in the morphological parameters(width,depth,and cross-sectional geomorphic coefficient)of the main channel are analyzed in this paper.The results show that before the operation of the Xiaolangdi Reservoir(XLDR)from 1986 to 1999,the main channel shrunk continually,with decreasing width and depth.The rate of reduction in its width decreased along the river whereas that of depth increased in the downstream direction.Because the rate of decrease in the width of the main channel was greater than that in channel depth,the cross-sectional geomorphic coefficient decreased in the sub-reach above Gaocun.By contrast,for the sub-reach below Gaocun,the rate of decrease in channel width was smaller than that in channel depth,and the cross-sectional geomorphic coefficient increased.Once the XLDR had begun operation,the main channel eroded continually,and both its width and depth increased from 2000 to 2015.The rate of increase in channel width decreased in the longitudinal direction,and the depth of the main channel in all sub-reaches increased by more than 2 m.Because the rate of increase in the depth of the main channel was clearly larger than that of its width,the cross-sectional geomorphic coefficient decreased in all sub-reaches.The cross-sectional geometry of the main-channel of the lower Yellow River exhibited different adjustment patterns before and after the XLDR began operation.Before its operation,the main channel mainly narrowed in the transverse direction and silted in the vertical direction in the sub-reach above Aishan;in the sub-reach below Aishan,it primarily silted in the vertical direction.After the XLDR began operation,the main channel adjusted by widening in the transverse direction and deepening in the vertical direction in the sub-reach above Aishan;in the sub-reach below it,the main channel adjusted mainly by deepening in the vertical direction.Compared with the rates of decrease in the width and depth of the main channel during the siltation period,the rate of increase in channel width during the scouring period was clearly smaller while the rate of increase in channel depth was larger.After continual siltation and scouring from 1986 to 2015,the cross-sectional geometry of the main-channel changed from wide and shallow to relatively narrow and deep.The pattern of adjustment in the main channel was closely related to the water and sediment conditions.For the braided reach,the cross-sectional geomorphic coefficient was negatively correlated with discharge and positively correlated with suspended sediment concentration(SSC)during the siltation period.By contrast,the cross-sectional geomorphic coefficient was positively correlated with discharge and negatively correlated with SSC during the scouring period.For the transitional and meandering reaches,the cross-sectional geomorphic coefficient was negatively correlated with discharge and positively correlated with SSC.

The Impacts of Different Bromide Concentrations and Advanced Oxidation Ways on the Bromate Generation

Taking reservoir water diverting from Yellow River as raw water, and using 5 m^3/h of pilot device, the impacts of different bromide concentrations and advanced oxidation ways on bmmate generation in effluent of ozone -upward flow BAC -sand filtration technology. Results showed that when bromine ion of raw water was about 100 μg/L, and ozone dosage was 2 mg/L, bromate exceeding risk existed in the effluent of ozone - upward flow BAC technology, and bromate content in the effluent reached 10 μg/L. Moreover, generation amount of bromate had certain linear rela- tionship with bromine ion of influent. Both dosing hydrogen peroxide and potassium permanganate could effectively inhibit bromate production, and there was no bromate generation in final effluent of the technology. Moreover, it also could improve the removal of major pollutants in the water by the combined process. Compared with advanced oxidation of hydrogen peroxide, potassium permanganate pre-oxidation could better control production costs.

黄河下游花园口以上河段滞沙能力分析

黄河下游河床调整主要取决于来水来沙和河床边界条件,河床调整沿程不均衡特征明显,花园口以上河段床演变对水沙条件的变化响应尤为突出,泥沙冲淤调整幅度最大。基于河道冲淤及水沙演进特性、滞沙可行性、河槽几何特性等分析,提出了花园口以上河段可作为泥沙天然反调节“库”概念,结合黄河下游实测洪水资料,采用水力计算方法,计算了花园口以上河段的河槽排洪能力及不同河槽规模条件下河槽允许滞沙量,提出了反调“库”滞沙能力,可为小浪底水库排沙指标的确定提供依据,对维持小浪底水库有效库容、弥补后续清水河床沙源不足、改善黄河下游河槽冲淤不均衡现象具有重要意义。

Boosting spring runoff into the sea by reservoir regulation and its potential for estuarine fishery recovery

With global surge in reservoir construction over the past decades,river systems worldwide have been profoundly fragmented.Consequently,flow manipulation by reservoirs has altered the natural hydrological processes,resulting in extensive modifications of fluvial-marine ecosystems.Mitigating the adverse ecological consequences of reservoirs has become a global concern and has garnered increasing attention.The Yellow River,as one of the most extensively manipulated river systems globally,has experienced substantial changes in the amount and timing of water discharge due to the presence of numerous reservoirs scattered throughout its catchment area.These alterations have caused physicochemical changes in the estuary and subsequent modifications to the estuarine ecosystem.In recent years,the Yellow River Conservancy Committee initiated the release of water through the Xiaolangdi Dam during the major spawning period of fisheries,specifically in the spring,with the aim of improving the estuarine ecological environment.From 2011 to 2020,a total of 84.05 km^(3)of water was discharged from the Xiaolangdi Reservoir during spring seasons,of which 40%(33.16 km^(3))constituted water impounded within the reservoir during preceding months.Correspondingly,the spring water discharge from the Yellow River to the sea increased significantly from 1.50 km^(3)/yr to 3.46 km^(3)/yr in the past decade,leading to a decrease in estuarine salinity by 1.6 PSU.The estuarine fishery resources,such as fish eggs in the Yellow River estuary,have demonstrated evident improvement.The reservoir regulation in the Yellow River,which has successfully enhanced spring water discharge and subsequently restored estuarine fishery resources,presents an effective attempt for mitigating the adverse ecological effects associated with reservoirs.

黄河百年径流系列连续枯水段识别和用水特征分析

连续枯水给黄河流域水资源安全造成了严重威胁。采用黄河干流兰州断面和花园口断面1920—2019水文年系列,通过距平法和标准化径流指数识别了百年系列连续枯水段,分析了枯水段的用水特征。结果显示:两断面均经历了1922—1932水文年和1990—2002水文年连续枯水段,均表现出连续枯水段和极端枯水年叠加的特征;1990—2002水文年连续枯水显著减少了入海水量;在1990—2002水文年连续枯水段初期,枯水对黄河流域及供水区用水量影响不明显,但在后期用水总量及农业用水量均大幅度减少;1990—2002水文年连续枯水段后期遭遇短期极端枯水对用水造成重大影响;龙羊峡水库在连续枯水段发挥了多年调节作用,支撑了流域供水安全。但是龙羊峡水库年际补水能力有限,未来在国家水网建设背景下,应通过建设古贤水库和跨流域调水工程提升应对连续枯水的流域水资源安全保障能力。

新形势下黄河调水调沙“丰调枯蓄”运用方式

调水调沙是黄河保护治理的重要举措。近年来,黄河水沙情势以及水库和河道边界条件发生了明显变化,现状调水调沙运用方式不能满足新形势下水沙调控多目标协同的需求。基于黄河水沙特性以及多年调度经验,提出“丰调枯蓄”的调水调沙思想和运用方式,即根据来水条件变化灵活地调整当年调水调沙策略,丰水年多开展调水调沙以使水库多排沙、河道多输沙,平水年适当开展调水调沙以满足多目标需求,枯水年不开展调水调沙以蓄水兴利。数字模型计算结果表明,相较于现状运用方式,“丰调枯蓄”运用方式可实现调水调沙的年际调度,使小浪底水库排沙、供水、生态、发电效益得到全面提升,计算期50 a水库累计淤积量减少5.78亿m^(3),不满足下游供水的年均时间少1.1 d,出库含沙量大于80 kg/m^(3)的年均时间少0.9 d,年均发电量增加1.2亿kW·h。

基于长时序稠密遥感数据分析黄河流域大中型湖库水域面积动态变化特征

黄河流域在我国经济社会发展和生态安全中具有重要地位。但从全流域的角度,基于长时序稠密遥感数据对黄河流域大中型湖库开展的研究却较少。本文基于MODIS 8天合成数据,提取了2000—2020年黄河流域大中型湖库长时序的水域信息,分析其时空变化特征,结果表明:从月际变化看,3—5月为水域面积第一个快速增长时期,6—10月为第二个增长时期,在10月达到最大值,10月之后逐渐下降,至次年2月达到最小值;从年际变化看,近20年上、中、下游湖库水域面积均呈现增长趋势,其中上游地区对全流域面积增长的贡献度最大,中游次之;湖库水域空间分布不均衡,上、中、下游近20年湖库水域面积平均占比分别为69.27%、25.02%、5.72%。

小浪底水库调控后黄河下游冲淤规律与水沙调控指标

为科学指导黄河调水调沙调度实践,根据小浪底水库调控后黄河下游冲淤规律对水沙调控指标进行优化。选取2011—2022年黄河下游实测121场不同含沙量级水沙过程,分析黄河下游水沙特点及其冲淤效率与水沙条件的响应关系,以黄河下游不淤积以及主槽过流能力不降低为总体目标提出水沙调控指标。结果表明:①小浪底水库对黄河下游水沙过程具有两极分化的调控作用,高含沙量水流(平均含沙量S av>10 kg/m^(3))的沙量全年占比为94%,清水水流(S av<1 kg/m^(3))的水量全年占比为85%。②高含沙量水流的淤积效率与平均含沙量呈正相关线性关系。③清水水流的冲刷效率与平均流量呈正相关对数关系。④对于高含沙量水流,丰水年调控水量为80亿m^(3),平均流量为2000~4600 m^(3)/s,平均含沙量为50 kg/m^(3);平水年调控水量为10亿m^(3),平均流量为2000~4600 m^(3)/s,平均含沙量为150 kg/m^(3);枯水年水库不排沙。对于清水水流,需要避免下泄平均流量在800~1800 m^(3)/s范围内的水流过程。

银川“西线供水”工程污染物水动力—水质传递模型

文章采用实地测量、实验和数值计算的方法,利用分析化验、实测数据建立并验证引水管道一维水动力—水质数学模型,建立西夏水库二维水动力—水质数学模型并对水流和水质进行数值模拟。利用FLUENT软件,根据实测水文和水质数据,建立并验证适合西线供水工程的数学模型,利用建立的数学模型进行水流和水质指标浓度的数值模拟研究,验证结果基本符合实际情况,为后续以黄河水为水源的西夏水库在污染物扩散机制、预防、处理等方面开展研究提供了良好的理论保障。

不同水源特征水库中溶解性有机物的光学特性对比

为考察A水库(“引黄工程”水源水库)与B水库(普通类型水库)的溶解性有机物(DOM)在相对分子质量大小、组成特征及来源方面的差异,采用紫外-可见光谱技术以及三维荧光光谱技术结合平行因子分析法,针对A水库和B水库水体中DOM的吸收参数特征和荧光特征进行了研究。结果显示:A水库和B水库的DOM均有较强的自生源特征,但两水库的DOM在组成特征和来源上存在一定差异。B水库样本中存在长波类腐殖质C1(E_(x)=350 nm,E_(m)=454 nm)、类色氨酸物质C2(E_(x)=300 nm,E_(m)=361 nm)和类色氨酸C3(E_(x)=220 nm/250 nm,E_(m)=347 nm)3个荧光组分,而A水库样本中存在长波类腐殖质C1、类色氨酸物质C2两个荧光组分,说明A水库的组成特征相对更加简单。DOM吸收参数特征分析显示,A水库水质状况良好,其DOM相对分子质量较大,主要来自自生源;而B水库处于富营养状态,其DOM相对分子质量较小,富里酸成分和水体芳香性较高,水生环境中维管束植物输入较为丰富,主要来自入库河流和自生源。光谱指标差异性分析显示,A水库DOM外源输入比例小于B水库,同时A水库的水质污染源更多以陆源输入为主。研究揭示了水库中DOM的光学特性,可反映水库的环境污染程度和富营养化程度,为进一步探究DOM在不同水源特征水库的环境行为特征及水库水质保护等提供参考。

55年来黄河下游逐日水沙过程变化及其对干流建库的响应

以55年来(1950—2004年)黄河下游花园口和利津水文站逐日水沙资料为依据,将黄河下游水沙变化分为5个阶段,分别与4个黄河干流水库的开始运作时间对应,分析和对比了花园口和利津两站5阶段逐日水沙记录和图谱特征和变化。结果显示黄河下游逐日水沙特征在干流水库的运作下发生显著的阶段性改变,至小浪底水库建成后发生了根本性变化,主要是洪峰和沙峰消失,传统汛期与非汛期季节划分趋于模糊,调水调沙短期内的输沙量占全年输沙量的2/3以上,下游由淤积变为冲刷、可能产生泥沙异重流的天数大幅度减少。下游河道有显著的削峰、滞洪和淤沙作用,花园口/利津站3—6月逐日水沙量差距分阶段快速加大,最大可达20倍,表明下游耗水增加并集中在春灌时段,是入海水量减少的主因之一。目前,水库联合调水调沙期间是河口异重流发育的最佳时段。55年来黄河下游逐日水沙过程的变化表明,黄河逐日水沙特征发生了受控于人类活动的根本性变化。

龙羊峡水库水温结构演变及其对下游河道水温影响

多年调节水库由于年际运行过程的差异引起水库水温结构变化,探明其规律及对下游河道水温响应具有重要意义。以黄河龙羊峡水库为研究对象,利用水库蓄水后的1988～2008年运行过程及水温观测资料,分析了水库运行方式与水温结构变化关系,探讨了水库不同运用过程对下游河道水温的影响。研究结果表明:龙羊峡水库水温结构演变及其对下游河道水温影响程度与水库运用过程密切相关。12～3月,水温结构为弱分层或等温分布,较高水位的蓄热增温效应明显,下游河道水温与水库水位变化具有同相位关系;5～10月,水温结构为分层分布,水位是决定分层形态变化最主要因素,下游河道水温与水库水位变化具有反相位关系,同时,水位与河道水温在不同的出入库水量条件下,呈现不同的线性相关关系。11月和4月,水温结构近乎为等温状态,也是水温结构变化的转折点。研究成果为分析大型水库在不同运行条件下水温结构及下游河道水温提供一定的参考依据。

黄河上游水沙变化及成因分析

利用黄河上游的实测资料,以头道拐断面为主要研究对象,从径流泥沙的年际变化、年内分配、洪水特征等方面分析了上游水沙变化特点,突变点为刘家峡和龙羊峡水库投入运用时间。对不同影响因素的研究认为,天然径流量的减少和耗水量的增加是造成上游水量减少的直接原因,龙羊峡和刘家峡水库的调节使天然的年内径流量重新分配,水库的削峰作用和调节流量过程,造成了水库下游洪峰流量的大幅度减小和流量过程的均匀化,从而对河道输沙产生十分不利的影响。正确认识水沙变化产生的原因及其带来的负面影响,可为水资源的合理开发、上游宁蒙河道的综合治理提供参考。

黄河中下游水库汛限水位与防洪体系风险分析

黄河中游四库(三门峡、小浪底、陆浑和故县水库)在中下游的防洪体系中有着重要的地位,也对黄河中下游的水资源分布产生很大的影响。根据黄河中下游水库及黄河中下游防洪工程体系的运行调度规则,考虑设计洪水典型选择、洪水预报误差和水库调度滞时的不确定性影响,利用蒙托卡罗法模拟洪水过程,实现了洪水典型选择、洪水预报及调度滞时不确定性因素影响的定量转化,分别计算了前、后汛期8种汛限水位方案下的黄河中下游水库及下游的防洪风险指标值,在对各方案的风险进行比较和评价的基础上,推荐了小浪底水库、陆浑水库和故县水库前、后汛期相对合理的汛限水位方案,为定量考察水库防洪调度及下游防洪风险率、合理选择动态的汛限水位提供参考依据。

无机-有机复合混凝剂处理夏季引黄水库水的对比研究

合成了具有不同Fe（Al）/聚二甲基二烯丙基氯化铵（PDMDAAC）质量比的无机-有机复合混凝剂PFC-PDMDAAC和PAC-PDMDAAC,并对夏季引黄水库水进行混凝处理.考察了复合比例、投药量、pH值和投加方式对浊度、有机物和叶绿素-a的去除效果;并通过混凝过程中形成絮体的Zeta电位的变化分析了2种混凝剂的混凝机理.结果表明,无机-有机复合混凝剂处理夏季引黄水库水的效果好于2种单独成分的复配使用;复合比例对PFC-PDMDAAC和PAC-PDMDAAC处理夏季引黄水库水的效果影响较大,Fe（Al）/PDMDAAC质量比为4：1,投药量为4mg/L时混凝效果最好;与无机混凝剂相比,复合混凝剂的最佳pH值范围较广,可在5.0~8.0的pH值范围内取得良好的混凝效果;2种混凝剂相比,PAC-PDMDAAC对浊度和叶绿素-a的去除效果较好,而PFC-PDMDAAC对有机物的去除效果更佳.

黄河调水调沙调控指标及运行模式研究

分析了小浪底水库运用以来黄河调水调沙运用效果及出现的新情况,从充分发挥调水调沙水流输沙效率出发,研究提出了黄河调水调沙调控指标,即调控流量为2 500～4 000m3/s,洪水历时不小于6d,汛前调水调沙洪水峰型宜采用矩形峰,在调水调沙水量充足的条件下,调控流量在保障下游滩区安全的前提下取大值;根据当前小浪底水库所处的运用阶段和水沙调控运用的要求,提出小浪底水库调控目标应转向水库适度拦调泥沙,尽可能长期维持黄河下游4 000m3/s左右中水河槽,调水调沙运用应综合考虑小浪底库区淤积和下游河道主槽过流能力变化等因素,选用适宜的调水调沙运用模式。