MIXING OF SALT WATER AND FRESH WATER IN THE CHANGJIANG RIVER ESTUARY AND ITS EFFECTS ON SUSPENDED SEDIMENT

Using field hydrological data, the relationship between the mixing of salt water and fresh water and the tidal range/ high tidal level in the Changjiang (Yangtze) River estuary is discussed, and the transporting and concentrating of suspended sediment in the estuary were also analysed in respect to the circulation, flocculation and stratified interface resulting from mixing.The calculation results by two-dimentional box model have confirmed the effects of the circulation on the concentrating of suspended sediment in the estuary. The conclusions derived from this work have deepened the understanding on the mixing in the Changjiang River estuary and are of significance in bo’th theory and practice.

Three Dimensional Baroclinic Numerical Model for Simulating Fresh and Salt Water Mixing in the Yangtze Estuary

For simulating fresh and salt water mixing in estuaries, a three dimensional nonlinear baroclinic numerical model is developed, in which the gradients of horizontal pressure contain die gradient of barotropic pressure arising from the gradient of tidal level and the gradient of baroclinic pressure due to the gradient of salinity. The Eulerian-Lagrangian method is employed to descretize both the momentum equations of tidal motion and the equation of salt water diffusion so as to improve the computational stability and accuracy. The methods to provide the boundary conditions and the initial conditions are proposed, and the criterion for computational stability of the salinity fields is presented. The present model is used for modeling fresh and salt water mixing in the Yangtze Estuary. Computations show that the salinity distribution has the characteristics of partial mixing pattern, and that the present model is suitable for simulation of fresh and salt water mixing in the Yangtze Estuary.

A method for estimating the fresh water-salt water interface with hydraulic heads in a coastal aquifer and its application

Examining the descriptions of piezometric heads at two points in both the salt water and fresh water zones reveals that when the groundwater flow system is in steady state and satisfies the Dupuit assumption, the location of the fresh water-salt water interface in a homogeneous, isotropic, and unconfined coastal aquifer can be estimated based on a piezometric head of fresh water at a point in the fresh water zone （from the water table to the interface） vertically lined up with a piezometric head of salt water at a point in the salt water zone （from the interface down）. Research shows that the new method is a general relation and that both the Hubbert relation describing the location of the interface and the Ghy- ben--Herzberg relation are special cases of this method. The method requires two piezometric wells to be close to each other and each tapping into a different zone. Measurements of piezometric heads at a well cluster consisting of piezometric wells tapping separately into fresh water and salt water zones near Beihai, China at 5-day intervals for 15 months are used to illustrate the estimation of interface location. The depth of the interface for well H5 ranges from 32 to 72 m below the sea level.

Seawater Intrusion and Salinization Processes Assessment in a Multistrata Coastal Aquifer in Italy

This paper presents the results of the investigations, driven by different techniques, including environmental tracers and geophysical methods, in the aim of better understand the causes of the current salt-water intrusion in the Pontina Plain, in the south of the Lazio Region (Italy). In the last 50 years many investigation campaigns have been carried out to evaluate the evolution of salt-water intrusion. This is an area with a strong man-made residential and tourist impact and, in the some cases, it is characterized by intensive agricultural practices. Therefore, it can be affected not only by salt-water intrusion, but by the salinization of its groundwater also due to other factors. All these factors have led the Pontina Plain to a groundwater situation which makes the groundwater resource management and the planning of their future exploitation very difficult.

Hydrochemistry of the Gasikule Salt Lake,Western Qaidam Basin of China

The Qaidam Basin is a large intermontane depression in Qinghai Province,China,which located on the northern margin of the Tibet plateau,and surrounded by the Qilian,Kunlun and Aljun mountains which rise to more than 5000m.Some 27 salt lakes occur within the basin,occupying an area of approximately 1500 km2.Additionally,there are extensive areas of dry playas.Together,the playas and salt lakes cover about one quarter of the total basin area.Whereas the western

一种核电厂重要厂用水泵房环境温湿度高处理方法

高温高湿气候时,东南沿海核电厂重要厂用水泵房频发温度高报警或设备凝露问题,影响泵电机运行安全,降低核电厂冷源安全可靠性。因此,在不改变当前通风方式情况下,提出在泵房进风风室增加一种新风混风制冷机组进行空气温湿度处理的方法。机组采用两路新风,将经制冷除湿后的新风与外界新风混合。通过计算确定进风参数。该方法无需冷却所有新风,无需再热段,通过混风升温降低相对湿度,可以彻底解决所有工况下泵房环境温度、湿度超标问题,且兼顾经济性。

SALT-FINGERING OF POLLUTANT VERTICAL MIXING IN STATIC THERMAL-STRATIFIED WATER

Pollutant vertical mixing in stratified waters is a key factor that affects the vertical pollutant distribution in deep thermal-stratified reservoirs. This article presents an experimental study of the vertical mixing in thermal-stratified waters and an analysis of the retarded tracer jet diffusion in the thermocline layer. In the experiment, Reynolds number rapidly decreases from 104 to 10I. The stronger the stratification, the more seriously retarded the mixing will be. Some small tracer blobs may penetrate the thermocline layer into the hypolimnion layer even the main tracer cloud is retarded. According to its appearance, it can remain with salt-fingering, where the blobs are isolated away from the main cloud and mixed with the surround cold water in the hypolimnion layer. Therefore, the vertical distribution of the tracer under the thermocline layer would take larger values than expected. According to measurements, the isolated blob contents are accounted for about 5%-20% of the main tracer cloud, and are decreased with the increase of the stratification intensity. Results also show that the stronger the stratification, the smaller finger width would be. The averaged width of the incipient fingers is proportional to -0.3272 of the thermal Rayleigh number, Rat, in the turbulent jet fluid. power of the temperature gradient, AT/Az, or - 0.2823 power

超采引起的河北平原东部地下淡水和地下咸水变化--以廊坊市东部和沧州市东部为例

自1975年以来,河北平原东部地下水严重超采引起一系列地质环境问题。基于河北平原东部(廊坊市东部和沧州市东部)2017年高密度地下水位统测数据、地下水开采量数据,判断河北平原东部地下水开发现状。通过分析研究区深浅层地下水水位数据、开采量和资源潜力,认为近年来河北平原东部地下淡水存在严重超采情况。通过对研究区深层地下水取样分析数据与水质历史背景数据开展对比分析,同时布设高密度电法进行物探解译,得出现状地下咸水底界,将之与20世纪70年代研究区的地下咸淡水分界数据对比认为,研究区地下淡水超采,引发地下咸淡水分布产生较大变化,同时对引起变化的主导因素进行了分析。研究有助于深入认识河北平原东部咸水区地下水开发利用条件,为推动河北平原东部咸水区的地下淡水资源合理开发提供科学依据。

电阻率测深法在咸淡水界面探测中的应用

通过电阻率测深法探测沧州献县的地下咸淡水界面,首先结合水文地质条件的综合研究,通过小四极测试法对工作区内不同岩性地层做了物性测试;根据地下咸淡水界面两侧存在着明显的电阻率差异这一地球物理前提条件,布置了7条测线,并进行反演和解释,查明了研究区地下0~250 m深度咸淡水分布情况。结果表明,区域内咸淡水分界线近NE走向,其西北区面积约1/3范围为淡水区,分界线东南大片面积略超2/3范围为咸水区;咸水区内有3个面积较小的淡水区,咸水与淡水分界面深度总体呈现西浅、逐渐向东变深的趋势,并存在4个下凹幅度不等、影响面积及特征不同的漏斗区。研究证明电测深方法在地下水勘查、咸淡水界面勘查中具有良好的有效性。

氯化钾浮选尾盐溶矿回收钾相图分析及工艺研究

通过对冷分解—正浮选工艺生产氯化钾排出尾盐的研究,针对不同氯化钾含量的尾盐,利用水盐相图进行尾盐分解最佳需水量的确定,并对尾盐分解液蒸发分析,对在相图中处于钾石盐结晶区的尾盐分解液进行兑卤研究,确定最佳兑卤比例,兑卤完成液经盐田摊晒可得到生产氯化钾所需光卤石,提高钾资源利用率,为企业创造可观的经济效益。

Sea water intrusion and salt water intrusion in the coastal area of Laizhou Bay

The characteristics, pattern, hydrodynamic and hydrochemical features, and the movement pattern of the salt water-fresh water interface of the sea water intrusion and the salt water intrusion, which occur in the coastal area of Laizhou Bay in Shandong Province, are analysed. The characteristics of the two kinds of intrusion are compared as well. A three-dimensional sea water intrusion model to describe the sea water intrusion with a transitional zone 1.56.0 km wide in the phreatic aquifer and a solute transport model describing the behavior of cations exchange in the process of sea water intrusion are established.

醇-水混合溶剂中水盐体系相平衡研究进展

水盐体系相平衡的研究是无机盐化工的理论基础,对于盐湖资源的开发和利用有着非常重要的意义。概述了甲醇-水、乙醇-水、多元醇-水混合溶剂体系中的相平衡研究,总结了各混合溶剂体系的特点和研究进展。

连续混配耐盐型压裂液的性能评价

制备了一种缔合聚合物型耐盐速溶减阻剂(MRFF),并搭配小分子阳离子防膨剂(RF-03)和油水双亲润湿剂(DE-01)组成滑溜水压裂体系。室内实验评价结果表明,MRFF溶解速度快,在质量分数0.8%时,5 min增黏速率达96.8%;在8.5×10^(4)mg/L盐水中仍具有黏度,盐水中的减阻率为70.5%;滑溜水压裂体系配伍性良好,满足连续混配要求。物理模型实验结果表明,该压裂破胶液的岩心渗透率恢复可达90.85%,提高采收率为26.86%。

2022年长江口压咸补淡调度实践及成效

2022年长江流域出现罕见的“汛期反枯”现象,径流量显著偏少,长江口咸潮入侵发生时间早、持续时间长、入侵程度严重。开展水工程群联合调度是压咸补淡、保障供水安全的重要举措。针对长江口咸潮入侵特点,基于长江流域水文预报调度体系,通过搭建长河系、远距离、多类水工程综合影响的一维水力学模型进行多工况场景模拟,并结合原型资料分析,从调度时机和调度目标两个角度提出了适应长江流域现状水工程群的压咸补淡调度策略。通过开展水工程群压咸补淡调度,明显抬升了中下游沿程水位,减轻了长江口咸潮影响,基本缓解了供水紧张的局面,取得了显著的社会效益和生态效益。提出的策略可为今后长江口地区的压咸补淡调度提供技术参考。

河沙与有机肥对盐碱土改良效果及作物生长指标的影响

为寻求适宜黄河三角洲地区盐碱地改良方案,通过室内盆栽试验,探讨了河沙与有机肥单施及二者耦合作用对盐碱土水盐分布及作物生长指标的影响。试验共设置CK(对照)、M1(5 t/hm^(2)有机肥)、M2(10 t/hm^(2)有机肥)、M3(15 t/hm^(2)有机肥)、S(15%河沙)、M1S、M2S和M3S八个处理。结果表明:有机肥和河沙单施均使土壤含水率增加,两者配施处理对土壤含水率的提升效果更为显著,以M1S处理效果最优,较CK增加9.47%;与有机肥处理相比,掺沙更有利于降低土壤含盐量,S处理脱盐效果最优,较CK降低8.25%,肥沙配施的M1S处理略低于S处理;有机肥单施和肥沙配施均降低了土壤pH值,其中M2S处理改良效果最好,M1S略小于M2S;各处理均增加了小麦株高和干物质量,其中M1S处理促进作用最大,较CK增加20.17%和14.28%。本研究肥沙配施的M1S(5 t/hm^(2)有机肥+15%河沙)为改良黄河三角洲地区中度盐碱土的最佳方案。

潮间带地热田水化学特征及成因机制分析

广东省江门台山汶村潮间带地热田地热资源储量丰富,研究其水化学特点、成因机制和热储温度可为后续开发利用提供参考。通过Piper三线图分析地热水水化学特点,根据代表组分离子比例系数和其日变化、年变化规律分析地热水成因机制;通过氢氧同位素分析并定量估算丰水期与枯水期地热水中咸水-淡水混合比例;利用Na-K-Mg三角图和地热温标公式法估算地热田热储温度。结果表明:研究区地热水属海相沉积地热水,热储温度约150℃,为深部热源沿断层上升过程中受浅表淡水和海水混合作用的结果,丰水期和枯水期的淡水比例分别为77.60%和58.76%。

莱州湾地下卤水资源利用与相图分析

介绍了莱州湾地下卤水的水质特征,简述莱州湾地下卤水的资源利用情况和典型生产利用过程;以水盐体系相图理论为指导,对莱州湾地下卤水水质的长周期变化进行分析,说明现有原盐生产中面临的困境;对莱州湾地下卤水资源利用中兑卤法生产硫酸钾的生产过程进行典型系统分析,介绍工业化中的技术特点及资源回用的工艺;对膜分离技术在卤水纳滤精制过程中的工业化应用过程进行了相图理论的解析,并从水盐体系相图的角度,对利用不同选择性纳滤膜组合进行多段纳滤生产硫酸镁的技术路线的可能性进行分析;简述了沸石离子筛提钾技术应用于地下卤水的可能性,对沸石离子筛技术提钾工艺的后端分离技术的相图利用进行分析,演示了硝酸钾产品的蒸发结晶分离的可能工艺技术路线。

蜡油加氢热高分气/混合氢换热器腐蚀泄漏分析及防护

某公司蜡油加氢装置热高分气/混合氢换热器E5102在运行9 a后发生内漏,导致装置被迫紧急停工检修。检修结束后,对管束的腐蚀泄漏原因进行分析。通过宏观观察、管束测厚、元素分析及离子分析,结合工艺模拟计算、腐蚀机理分析和注水情况分析,认为管程NH_(4)Cl结盐导致垢下腐蚀、注水冲洗不彻底及注水方式不合理是引起换热器腐蚀泄漏的主要原因,并提出了改进措施及建议,希望对各企业预防加氢装置热高分气/混合氢换热器的腐蚀泄漏有一定帮助。