Modeling Flow,Nutrient, and Sediment Delivery from a Large International Watershed Using a Field‐Scale SWAT Model

A large international watershed, the St. Clair‐Detroit River System, containing both extensive urban and agricultural areas, was modeled using the Soil and Water Assessment Tool (SWAT) model. The watershed, located in southeastern Michigan, United States, and southwestern Ontario, Canada, encompasses the St. Clair, Clinton, Detroit (DT), Sydenham (SY), Upper, and Lower Thames subwatersheds. The SWAT input data and model resolution (i.e., hydrologic response units, HRUs), were established to mimic farm boundaries, the first time this has been done for a watershed of this size. The model was calibrated (2007–2015) and validated (2001–2006) with a mix of manual and automatic methods at six locations for flow and water quality at various time scales. The model was evaluated using Nash–Sutcliffe efficiency and percent bias and was used to explore major water quality issues. We showed the importance of allowing key parameters to vary among subwatersheds to improve goodness of fit, and the resulting parameters were consistent with subwatershed characteristics. Agricultural sources in the Thames and SY subwatersheds and point sources from DT subwatershed were major contributors of phosphorus. Spatial distribution of phosphorus yields at HRU and subbasin levels identified locations for potential management targeting for both point and nonpoint sources and revealed that in some subwatersheds nonpoint sources are dominated by urban sources.     

长江上游地区泥石流灾害敏感性量化评价研究

泥石流敏感性分析对灾害分析评价预测具有重要作用。文章以长江上游为研究区,选择坡度、相对高差、地层岩性、年降雨量、地震烈度等5方面因素为评价因子,探讨运用GIS技术管理分析泥石流灾害信息和区域泥石流敏感性分析的方法。量化评价因子的作用分值大小,有效表达泥石流敏感性指数(DFSI),进而,结合空间分析与条件概率模型,实现了区域泥石流敏感性分析并制作了泥石流敏感性专题图。长江上游地区泥石流敏感性区域具有一定的规律性,高度敏感区主要分布在第一级阶梯与第二级阶梯的过渡地带,比较集中的区域有雅砻江中下游、安宁河、小江、普渡河、大渡河中下游、理塘河、白龙江、岷江上游、涪江上游等干支流的5～10 km范围内;中度敏感区主要分布在高度敏感区的外围约10～30 km范围内。利用历史泥石流资料验证,表明已经发生的泥石流主要分布在泥石流敏感性指数较高地区,说明敏感性分析的结果基本反映出研究区泥石流敏感性特性。     

低渗透介质中轻非水相流体迁移转化规律

本文利用COMSOL软件建立轻非水相流体(LNAPL)纵向迁移转化模型,采用有限单元法进行求解,预测污染物分布规律,并利用局部分析法进行参数敏感性分析.结果表明,大部分LNAPL会在水面以上聚集形成高的质量分布峰值区域,少部分克服毛细压力向下迁移,在自由相迁移范围内,其溶解相浓度达到或接近饱和溶解度;当顶部污染源消失后...     

基于物质流分析的中国减物质化趋势及循环经济成效评价

物质流分析通过测量经济活动物质投入的数量、强度及其变化即物质化或减物质化趋势,能够反映可耗竭自然资源损耗和环境退化的总体情况,也是评价循环经济发展成效尤其是资源综合利用对物质消耗影响的一个有效工具。论文运用统计学和计量经济学方法,分析了中国2000-2013年直接物质投入及其与特定经济特征的关系,确定了资源利用强度变化趋势,评价了中国循环经济实践尤其是资源综合利用的成效。发现2000-2013年中国直接物质投入总量持续增加、单位GDP直接物质投入先上升后下降,说明中国已进入了相对的减物质化阶段;第二产业比重先增加后下降的变化趋势是直接物质投入强度变化的格兰杰原因;中国的资源综合利用总量增加但综合利用率仍很低,未对直接物质投入强度产生统计学意义上的显著影响;未来中国直接物质投入总量和人均值在很长时间内还将继续增加。     

脉冲式流量波动对厌氧氨氧化UASB反应器的影响

通过试验模拟不同幅度、不同频率的脉冲式进水流量波动,研究脉冲式流量波动对已稳定运行的厌氧氨氧化UASB反应器性能的冲击影响.结果表明,在脉冲波动幅度小于60mL/min（上升流速1.33cm/min）范围内,厌氧氨氧化UASB反应器表现出良好的适应性和承受力,甚至对于高频率的波动冲击,出水也可达到一级A标准,NH₄⁺-N和NO₂^--N去除率都基本维持在80%以上,总氮去除率维持在70%以上.而当脉冲的波动幅度为100mL/min（上升流速2.22cm/min）时,则UASB反应器的出水水质波动性大,随着波动频率的增大,反应器的适应时间增长,一直到波动频率为1.5h时,反应器出水NH₄⁺-N和NO₂^--N浓度难以稳定在5mg/L以下.随着波动幅度由40mL/min增大到60,100mL/min,反应器内污泥中厌氧氨氧化菌的丰度值和厌氧氨氧化菌占全细菌的百分含量均呈现先增多后减少的趋势,在波动幅度为60mL/min时均为最大,可能是由于此时污泥和基质的混合与接触更为高效,氮去除效率高,更有利于厌氧氨氧化菌的生长.     

北方地区受污染河湖水体潜流湿地净化技术研究与工程应用

结合实验研究和工程应用实践,在湿地填料选择、水力负荷变化、植物特性、结构优化、越冬运行等方面,对我国北方地区潜流人工湿地设计、建设、运行管理中的关键技术问题开展了系统、深入研究.结果表明:石灰石、粗砂等脱氮除磷综合效果较好,且取材方便、价格便宜,应是人工湿地主选填料,钢渣、褐铁矿除磷效果良好、沸石的氨氮吸附能力强,可作为辅助材料;湿地植物对水质净化贡献约为5%～15%,其地上部分的生物量移除贡献不足5%,湿地植物对系统水力负荷维持、冬季保温、生态景观等还具有较大贡献;以植物保温为主,结合冰下取水、水位管理等可实现北方地区潜流湿地冬季正常运行;优化提出了竖向复合流湿地结构,具有节约用地、硝化-反硝化作用效果显著、抗淤堵等特点.研究成果已在工程实践中得到成功应用,对人工湿地在我国北方地区的推广应用具有重要借鉴意义.     

Transverse approach between real world concentrations of SO2, NO2, BTEX, aldehyde emissions and corrosion in the Grand Mare tunnel

With regard to automotive traffic, a tunnel-type semi enclosed atmosphere is characterized by a higher concentration of gaseous pollutants than on urban traffic roads and highlights the gaseous effluent species having an impact on material degradation. Therefore, a transverse approach between air quality and its consequences upon the longevity of materials is necessary, implying better knowledge of tunnel atmosphere and a better understanding of material degradation inside a tunnel for operating administration. Gaseous pollutant measurements carried out in a road tunnel in Rouen (Normandy) give the real world traffic concentrations of experimental exposure conditions. The sampling campaigns, achieved in summer and winter include SO₂, NO₂, BTEX and aldehyde analyses. Effluent profiles in the upward and downward tubes have been established. The current work shows that SO₂, NO₂, formaldehyde, acetaldehyde, propanal and butanal must be considered in the degradation process of materials in a stuffy environment. As regards NO₂, its concentration depends on the modification of the automotive fleet. The total aldehyde concentrations indicate no particular trend between the two bores. Formaldehyde, acetaldehyde, propanal, butanal and acrolein species are the most abundant species emitted by vehicles and represent 90% to 95% of the total aldehyde emissions.     

钙、镁离子在水流作用下对铜绿微囊藻生长的影响

为了解在"引江济太"过程中大量钙、镁离子的引入对铜绿微囊藻生长的影响,本实验在控制温度和光照条件下,室内模拟不同钙、镁离子浓度在两个特征流速5 cm/s和15 cm/s下微囊藻的生长。实验结果表明,微囊藻藻密度随钙、镁离子浓度的增加而增加,流速在15cm/s下微囊藻最大藻密度(9 236.4×104cell/mL)是流速为5 cm/s下最大藻密度(2 873.72×104cell/mL)的3倍,流速为15 cm/s下微囊藻最大比增长速率均较5 cm/s下的高。这可能是在水流产生的剪切力作用下藻细胞胞外多糖增加,粘附更多的钙、镁离子更利于钙、镁离子迁移到胞内,同时胞外附着的钙、镁离子尤其钙离子形成桥联,使微囊藻细胞形成群体产生微环境利于微囊藻的生长。水流对微囊藻利用钙、镁离子有重要的影响,这为有效调水抑制蓝藻生长提供科学依据。     

新疆“三十里风区”输电线路复合绝缘子故障分析

复合绝缘子是超高压输电线路中的关键设备之一,确保其可靠运行是维护电网安全的前提。新疆乌鲁木齐至吐鲁番750kV输电线路途径"三十里风区",当地10米高度处最高设计风速为42m/s,这对复合绝缘子的长期运行是一个巨大挑战。强风下的绝缘子伞裙摆动导致其根部材料疲劳,进一步产生微观裂纹,最终导致绝缘子撕裂故障。本文通过气候环境调研,分析了当地气候环境特征;通过故障分析,初步探明乐儿复合绝缘子伞裙撕裂过程;通过风洞实验研究,得到了伞裙在流体中的动态现象。通过以上分析,对于这项特殊微气候环境下的外绝缘典型故障,本研究探明强风下伞裙动态过程,并在伞裙故障产生原因方面进行一定探索,为最终解决该问题提供了有力的技术参考。     

Minimizing disruptions caused by damming and ensuring the health of downstream ecosystems

In view of the Brazilian Ten‐Year Energy Expansion Plan 2021, this article presents a discussion on environmental flow (e‐flow). The authors analyze the literature to show the evolution of publications concerning e‐flow releases from the perspective of ecosystems services preservation considering results from different case studies from throughout the world. Finally, two main recommendations are drawn regarding e‐flow are: (1) performing a holistic approach to e‐flow planning, including hydrological, hydraulic, water quality, habitat, and riparian zone considerations; and (2) installing in new structures adequate bottom outlets to allow a range of adjustable e‐flow from reservoir dams to reproduce natural flow variations.