Numerical modeling of solute transport in deformable unsaturated layered soil

The effect of soil stratification was studied through numerical investigation based on the coupled model of solute transport in deformable unsaturated soil. The theoretical model implied two-way coupled excess pore pressure and soil deformation based on Biot's consolidation theory as well as a one-way coupled volatile pollutant concentration field developed from the advection-diffusion theory. Embedded in the model, the degree of saturation, fluid compressibility, self-weight of the soil matrix, porosity variance, longitudinal dispersion, and linear sorption were computed. Based on simulation results of a proposed three-layer landfill model using the finite element method, the multi-layer effects are discussed with regard to the hydraulic conductivity, shear modulus, degree of saturation, molecular diffusion coefficient, and thickness of each layer. Generally speaking, contaminants spread faster in a stratified field with a soft and highly permeable top layer; soil parameters of the top layer are more critical than the lower layers but controlling soil thicknesses will alter the results. This numerical investigation showed noticeable impacts of stratified soil properties on solute migration results, demonstrating the importance of correctly modeling layered soil instead of simply assuming the averaged properties across the soil profile.     

Micropaticle transport and deposition from electrokinetic microflow in a 90° bend

In this study, the irreversible deposition of microparticles from electrokinetic microfluidic flow in a 90° bend was examined both computationally and theoretically. The flow and electric fields were firstly simulated by the finite volume method, and then a large number of microparticles were injected and traced by the one-way coupling Lagrangian model, incorporating the electrical, hydrodynamic and near-wall repulsive forces exerted on the microparticles. The simulation results indicate that the microparticles with larger size are repelled to close to the upper region of the outer wall under the effect of dielectrophoresis (DEP) force, and the near-wall repulsive force which prevented particles from colliding with the wall would decrease the particles’ ultimate deposition efficiency. In addition, the specified exponential relationship between the particle deposition efficiency and its relaxation time or particle Stokes number are theoretically derived when the near-wall repulsive force is considered or not.     

Influences of coastal underground reservoir construction and utilization on saltwater and freshwater transport law in aquifersEI北大核心CSCD

In order to reveal the impact of underground reservoir construction and extraction methods on the saltwater and freshwater transport law in coastal aquifers, a 300m × 900m × 30m conceptual numerical model was established. The variable density current simulation method of unconfined aquifer was used to analyze the saltwater and freshwater transport law in coastal aquifer under different extraction scenarios before and after the construction of underground dam. The results show that the construction of underground dam can significantly reduce the scope and degree of seawater intrusion. Groundwater extraction can accelerate the intrusion and diffusion of residual saltwater in underground reservoirs within a certain time range. The coefficient of saltwater intrusion is exponentially related to extraction scale and the distance between extraction wells and underground dams. Reasonable layout of the location and scale of extraction wells can effectively reduce the negative impact of groundwater extraction on water salinity in the reservoir area. © 2023, Editorial Board of Water Resources Protection. All rights reserved.     

Nonpoint source reduction to the nearshore zone via watershed management practices: Nutrient fluxes,fate, transport and biotic responses — Background and objectives

Studies that evaluate the linkages between watershed improvement through Best Management Practices (BMPs) and downstream outcomes are few. Water quality of coastal waters is often impacted by soil and nutrient loss from watersheds in agriculture. Mitigation of these impacts is of concern in the Great Lakes, the Finger Lakes Region of New York State, and generally in water bodies of North America. In this issue, we report on hypothesis-based research at the watershed level evaluating the impact of BMPs on mitigation of nonpoint sources of nutrient and soil loss to streams and the nearshore zone of a lake. Specifically, we hypothesize not only reductions in nutrient and soil losses from watersheds but also a resultant decrease in metaphyton (filamentous algae), coliform bacteria, and macrophyte populations in the nearshore at stream mouths draining sub-watersheds where BMPs were introduced. Small experimental sub-watersheds, predominantly in agriculture (> 70%), were selected to ensure that effects on downstream systems would not be confounded by other land use practices often observed in large watershed approaches. In this introductory paper, we provide background information on Conesus Lake, its watershed, and the Conesus Lake watershed project, a large multi-disciplinary study evaluating agricultural management practices. The series of papers in this volume consider the effect of BMPs designed to control nonpoint sources on water chemistry, metaphyton, macrophytes, and microbial populations in the coastal zone of a lake. Ultimately, this volume expands the basic understanding of the ability of BMPs to control nonpoint source pollution while contributing toward the goal of improving water quality of downstream systems including streams, embayments, and the nearshore of large lakes.     

The progress in the verification of key technologies for floating structures near islands and reefs

In 2019 a Scientific Research&Demonstration Platform was deployed near islands and reefs in South China Sea by a joint research group of 7 institutes and universities in China.It is a simplified small model of a two-module semi-submersible-type VLFS.The test on site has continued for more than one and half years since then for long-term observations to validate the developed key technologies for design and behavior predictions of floating structures deployed near islands and reefs.An integrated information system was set up to continuously collect and inspect the data of the encountered waves,structure responses,connector forces,mooring line forces,anti-corrosion status of the platform,the performance efficiencies of a floating breakwater nearby and a wave energy converter attached on the breakwater.In this paper,the status of the on-site measurements and validations of the key technologies are briefly described.     

全力以赴抗震救灾水利部门在行动

北京时间2008年5月12日14时28分,四川省汶川县发生里氏8级大地震. 地震发生时,全国除吉林、黑龙江和新疆维吾尔自治区没有震感外,其他省、自治区、直辖市和周边许多国家都有不同的震感,我国四川、重庆、甘肃、陕西、云南、青海、宁夏等地震感强烈,破坏特别严重的地区达10万平方公里.     

在全国违规水电站清查整改工作座谈会上的总结讲话

同志们: 全国违规水电站清查整改工作座谈会就要结束了,上午胡四一副部长作了一个非常重要的讲话,全面肯定了清查整改工作成绩,对下一步工作提出了明确的任务要求并进行了全面部署;国家安监总局王力争副司长通报了全国一季度安全生产情况,传达了国务院领导同志关于安全生产工作的最新指示,提出了下阶段安监部门进一步配合水利部门做好违规水电站清查整改工作的意见和建议;国家电监会吴晔副处长提出了进一步理顺体制机制,加强市场监管,从根本上消除违规水电站的意见;福建、湖南、广东、广西、重庆水利厅(局)和贵州铜仁地区水利局介绍了他们的做法和经验,会议还就贯彻胡四一副部长的讲话精神、进一步做好清查整改工作进行了讨论,大家提出了许多好的意见和建议.应该说,这次会议时间虽短,但开得紧凑,效果很好.     

密云南山滑雪场建设的水土流失防治对策

近几年郊外游玩成为都市人热衷的休闲项目之一,尤其是冬季滑雪.目前仅北京周边郊区就有大小规模不等的滑雪场13家,分布在密云、怀柔、延庆、昌平、顺义等郊区县.     

国家发展改革委关于印发可再生能源发展"十一五"规划的通知(上)

各省、自治区、直辖市及计划单列市、副省级会城市、新疆生产建设兵团发展改革委、经贸委(经委),国家电网公司、南方电网公司、中国华能集团公司、中国大唐集团公司、中国国电集团公司、中国科学院、中国工程院:     

辽宁农村水电的发展现状及问题研究

本文对辽宁省农村水电发展的现状及存在的问题进行了分析,从行业自身、市场和社会、生态环境等方面进行研究,提出建议.     

潮白河供水管理所水务信息化建设的思考

通过阐述水务信息化建设的重要意义,分析目前潮白河供水管理所信息化建设的现状和存在问题.针对实际情况,提出信息化建设的方法和建议.     

地震诱发的堰塞湖

堰塞湖是一种自然界经常发生的自然现象。主要是在一定的地质与地貌条件下，由于火山喷发物、滑坡体、泥石流、冰川堆积物等形成的自然堤坝横向阻塞河谷后，造成上游段壅水而形成的湖泊．随着成因的不同可分为火山堰塞湖、冰川堰塞湖等。其中．由于地震引发河道两侧山体滑坡或崩塌、滑坡体或崩塌体落人河道形成拦水堤坝、河水聚集成湖的现象称为地震堰塞湖。     

孙子与水:水无常形 兵无常势

在先秦诸子中,兵家是最受诸侯欢迎的一家。历史为兵家提供了驰骋的舞台;而战争,则为兵家提供了锻造的熔炉。春秋战国之际,一大批军事家走上历史的前台。但大浪淘沙,有兵圣之誉者,唯孙子一人。     

搜聚珍玩的癖好

与博弈投骰、登高远游、泛舟湖上、吹箫抚琴、吟诗作画、饮酒狂舞等娱乐活动相比,玩抚自己多年搜集的历代珍玩实在是充满静谧雅趣的消遣,它可使人心畅神怡,     

自序

苏天赐先生生前曾经写过一篇画集自序,本刊亦刊发在此,以飨读者。自从我进入这个绘画世界,就不能自拔!天地之宽广无垠比我所能感受到的超出太多,而我所能画出的比之于我所感受的又实在太少,于是     

房管科长如何把办证变成“摇钱树”

近年来,房价节节攀升,开发商赚了,炒房人发了,房屋中介火了,围绕房屋的产业链商机无限,谁料负责办理房产证的房产局工作人员也抓住这一机遇,联合地     

基于GIS的北京顺义区水环境评价

按照单指标评价法、肯得尔检验法、综合指标评价法等方法对顺义区进行了水质环境评价.结果表明:大部分地表水体(除潮白河)已经不能满足Ⅴ类水体(GB 3838-2002)的使用功能;大部分地下水体仍能满足Ⅲ类水体(GB/T 14848-93)的使用功能;废水排放量较大且以工业废水为主,并且农药化肥使用量也较大.在评价过程中充分利用了GIS的空间分析能力,有效地提高了分析的效率、准确性,形象地给出了分析结果.