不流动水对包气带溶质运移的影响研究进展

本文对考虑不流动水影响下的溶质运移模型、可动-不动区溶质运移模型、考虑吸附与降解作用的不流动水溶质运移模型进行了综述。指出对不流动水的研究已从盲端水扩展到内聚体间不动的水和远离流动区的水。其中，用可动-不动区模型可解释溶质运移中穿透曲线不对称的现象；用压力圆盘渗透仪可直接测量不动区的含水量使上述模型易于操作。并指出今后不流动水研究的方向应为不流动水分类的完善、不流动水对包气带水流的影响研究、参数的不确定性和尺度效应研究。     

基于遗传算法的田间尺度土壤水力参数与溶质运移参数优化

合理确定田间尺度土壤水力参数和溶质运移参数是保证农田土壤水盐动态模拟正确性的重要前提。本文开展了基于遗传算法(Genetic Algorithms,GA)与农田水文模型SWAP(Soil-Water-Atmosphere-Plant)耦合进行土壤水力参数和溶质运移参数优化的方法研究。在已有GA基础上引入了子体优生策略,并以完全嵌入方式耦合GA与SWAP模型。采用河套灌区曙光实验站的土壤剖面分层含水率(θi)和溶液浓度(cmli)、表土含水率(θsur)、实际腾发量(ETa)等观测资料,开展了田间尺度土壤水力参数和溶质运移参数优化的数值试验与相应分析。结果表明:(1)采用土壤分层信息(θi和cmli)作为观测数据,GA参数优化效果很好;(2)仅采用ETa作观测数据时,参数优化效果相对欠佳,需慎重使用,而结合ETa与θsur后可提高优化精度;(3)引入子体优生策略可提高GA的参数优化效率和精度。综上,结合GA与SWAP模型是优化田间尺度土壤水力参数和溶质运移参数的一种实用方法。     

基于遗传算法的田间尺度土壤水力参数与溶质运移参数优化

合理确定田间尺度土壤水力参数和溶质运移参数，是保证农田土壤水盐动态模拟与预测正确性的的重要前提。本文开展了基于遗传算法（Genetic Algorithms, GA）与农田水文模型SWAP（Soil-Water-Atmosphere-Plant）耦合进行土壤水力参数和溶质运移参数优化的方法研究。GA以选择、交叉和突变三个算子为基础，融入小生境技术、精英保留策略、Micro-GA算子、蠕式突变等改进算法，同时我们引入了子体优生策略。本研究以完全嵌入方式耦合了GA与SWAP模型，以河套灌区曙光实验站为背景，采用土壤剖面分层含水率(θi)和溶液浓度(cml i)、土壤表层含水率(θsur)、实际土壤蒸腾蒸发量(ETa) 作为观测资料，开展了田间尺度土壤水力参数和溶质运移参数优化的数值试验与相应分析。结果表明：(1) 采用土壤分层信息 (θi和cml i) 作为观测数据，GA参数优化效果很好；(2) 仅采用ETa作观测数据时的参数优化效果欠佳，需慎重使用，而结合ETa与θsur后可提高优化精度； (3) 引入子体优生策略可提高GA的参数优化效率和精度。综上，结合GA与SWAP模型是优化田间尺度土壤水力参数和溶质运移参数的一种实用方法。     

非稳定流条件下非饱和均质土壤溶质运移的传递函数解

根据溶质运移的传递函数模型Tromsfer Function Model, TFM理论，研究了非稳定流条件下非饱和均质土壤中表施和原有NO-3 N及原有Cl-的运移。由极大似然法估算了模型参数μ和σ2，求出了溶质运移的概率密度函数，计算了NO-3 -N的淋失量，并利用土壤中原有Cl-的动态，对NO-3 N的迁移过程进行了模拟，同时还估算了溶质的中值迁移时间tm和均值迁移时间相应的运移体积θst和θst。     

渗透系数的非均质性对地下水溶质运移的影响

本文应用贝叶斯推断方法和随机模拟技术,定量研究了渗透系数的非均质性对地下水溶质运移的影响,并进行了二维理想流的分析计算。计算时分别考虑了随机模拟引起的不确定性和随机模型中参数的不确定性的影响。计算结果表明,贝叶斯推断的参数后验分布是不对称的;当条件数据较多时,参数后验分布的标准方差较小,参数分布的集中趋势较明显;地下水溶质运移的不确定程度随着时间的推移而增加,随着条件数据数量的增多而减少;当考虑参数不确定性时,溶质运移的不确定程度明显增加。     

土壤中溶质运移的特性及模型研究

综述近年来土壤中溶质运移的机理、溶质的吸附模型和溶质运移数学模型等方面的研究现状,并在现有数学模型的基础上,探讨了这些模型目前需要解决的问题及未来发展趋势.     

基于Bayes理论的田间层状土壤水分运动参数识别及不确定性分析

土壤水分运动参数是非饱和带水分及污染物运移研究的核心参数,根据点尺度土壤样本的室内稳态试验得到的水分运动参数往往不能准确反映天然条件下田间尺度土壤水分运动特征。本文基于为时2年的田间土壤含水量观测数据(2013年为率定期,2014年为验证期),通过土壤转换函数得到了VGM(van Genuchten-Mualem)模型水力参数的先验分布,建立了反演层状土壤持水和导水特征的贝叶斯模型,采用自适应差分演化(DREAMZS)的采样方法,结合Hydrus_1d模型,对田间尺度土壤水分含量预测模型进行优化及不确定性分析,获得了水分特征参数的后验分布,分析了最优参数组的模拟效果及模型预测的95%的置信区间。结果表明,基于DREAMZS采样的Bayes方法可以实现田间尺度层状土壤水分特征参数的率定及土壤水分动态的模拟预测。率定结果显示饱和导水率Ks最不敏感,饱和含水量θs最为敏感,可识别性较高,室内试验反演得到θs可用于田间土壤水分运动的模拟。随着土壤含水量模拟深度的增加,PUCI(单位平均相对宽度所包含的实测点数据比例)值越大,模型预测的性能越高。模拟结果的不确定性主要由模型结构所引起,所以对模型结构的修改完善是未来提高模型预测的关键。     

VG模型参数对灌溉补给系数的敏感性分析

运用模型手段,计算灌溉补给系数时,VG 模型中水力参数的不确定性严重影响了灌溉入渗补给系数的可靠性,且目前针对非均质岩土层入渗及其水力参数敏感性的研究较少。基于新疆伊犁霍城县原位试验场灌溉试验,运用 HYDＲUS－2D 软件建立二维饱和－非饱和带水分运移数值模型,利用EFAST 法和 Morris 筛选法分析了 VG 模型中水力参数对灌溉补给系数的敏感性,并分析比较两种方法的一致性。研究表明: 当包气带岩性为均质结构时,θs( 土壤的饱和含水率) 及 n( VG 模型的形状参数) 共同影响着灌溉补给系数。当包气带岩性处于上粗下细的结构时,θs 对灌溉补给系数影响最大,即表明 θs 最为敏感,而且细颗粒 θs 相对于其他水力参数的耦合程度最大。n 直接影响着土壤水分特征曲线的整体形状。同时 EFAST 法和 Morris 筛选法对参数敏感性分析结果呈现较高的相关性。由于VG 模型中水力参数数量适中,EFAST 法较 Morris 筛选法工作量合理,同时对模型参数敏感性分析更加贴近实际。研究成果对获取包气带水分运移模型参数有着重要意义。     

奎河周边浅层地下水流及溶质运移数值模拟

根据典型地区地下水动态和溶质运移情况,结合水文地质条件和其他资料,建立了相应的水文地质概念模型。利用有限元数值模拟软件FEFLOW实现了对研究区地下水流系统和溶质运移的模拟。在水位过程线拟合、水位误差分析和溶质相关性分析的基础上,对地下水流系统和溶质运移模型进行了识别、校验,并利用所建立的数值模型预测了研究区地下水溶质运移演化情况。     

河流潜流带氮素迁移转化数值模拟研究进展

系统归纳了描述潜流带氮素迁移转化行为的水动力、溶质运移、微生物生长数学模型及其耦合关系,分析了耦合模型的主要参数及其影响因素,探讨了试验数据获取、过程耦合关系建立、模型参数识别对数值模拟不确定性的影响。针对现有研究的不足,提出了未来应加强潜流带原生环境监测、热传输过程与其他过程耦合、多维度多过程耦合模型优化计算等方面的研究。     

地下厂房施工过程的三维非线性数值模拟分析

根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。     

Call for Papers

正As the eldest and most distributed professional journal of water industry,Water Wastewater Engineering(W WE)gained very wide acceptance from the colleagues working in this field in this country since start publication in 1964.Now it is administrated by the Ministry of Construction of the People’s Republic of China and sponsored by the China Civil Engineering Society etc.     

Serial discontinuities in a Rocky mountain river. I. Distribution and abundance of plecoptera

Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m^?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m^?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m^?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m^?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m^?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river.     

Evaluation of freshwater mussel relocation as a conservation and management strategy

The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects.     

Impacts of Microcystis on algal biodiversity and use of new technology to remove Microcystis and dissolved nutrients

Cyanobacteria often dominate eutrophic lakes, outcompeting green algae that are required by fish and zooplankton. This study was undertaken to ascertain the impact of the cyanobacterium, Microcystis, on algal biodiversity. Under laboratory conditions, we found that the presence of Microcystis decreased phyla richness by 58%, phyla evenness by 47%, genera richness by 66% and genera evenness by 51%. Analysis by mixed anova s demonstrated a significant interaction between treatment and time and confirmed a significant reduction in richness and evenness of phyla and genera. We also conducted a phosphate restriction assay on the algae in Mason Lake (Irvine, CA, USA) and found that the threshold needed for algal growth there was 0.02 mg L^?1 PO₄. A pilot study was then conducted to test the effectiveness of the Blue Pro? water treatment facility in removal of this colonial organism from Mason Lake, in addition to removal of dissolved nutrients required for its growth. We measured a 97% reduction in Microcystis cells, a 72% reduction in chlorophyll‐a, and a 96% reduction in phosphate after just one 10 min cycle through the unit. Our study demonstrated that removal of Microcystis colonies may allow green algae to increase in numbers. This may improve algal biodiversity, which will benefit zooplankton and fishes.     

基于模型试验的河床砂砾石层基本特性研究

为了经济可靠地确定深厚覆盖层的基本特性参数,以大渡河双江口水电站坝基河床砂砾石层基本特性研究为工程背景,进行大尺寸模型试验,研究河床砂砾石层的旁压模量和动探击数随密度、级配以及上覆压力的变化规律。根据室内模型试验结果,结合现场旁压试验及钻孔试验成果,推断出坝址区河床砂砾石相关层位的密度,并依此进行砂砾石室内力学试验,获得设计所需力学参数。研究成果可为深厚覆盖层基本特性测试提供新的方法。     

SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN AQUATIC HABITATS OF A CULTIVATED FLOODPLAIN

The floodplains of lowland rivers contain diverse aquatic habitats that provide valuable ecosystem services but are perturbed when intensively cultivated. Hydrologic, water chemistry and biological (fish) conditions in five aquatic habitats along the Coldwater River, Mississippi, were measured for more than 4 years: the river, two severed meanders that functioned as backwaters, a managed wetland and an ephemeral channel draining cultivated fields. Off‐channel habitats were connected to downstream regions 0.10% to 32% of the dry season and 24% to 67% of the wet season. The median temperatures for the five monitored sites ranged from 18°C to 23°C, the median total solids concentration for all sites was 135 mg L^?1, the median total phosphorus was 0.29 mg L^?1 and the median total nitrogen was 1.56 mg L^?1. Chemical and physical water quality displayed strong seasonal differences between the wet winter/spring and the dry summer/fall periods so that temporal variation consisted of gradual seasonal trends superimposed on strong diurnal variations. All off‐channel habitats exhibited periods of hypoxia and temperatures >30°C during the dry season. Between‐site gradients of water and habitat quality were strongly coupled to water depth and runoff loading. The rehabilitation of one backwater by increasing water depth and diverting agricultural runoff was associated with improved water quality and fish species richness relative to an adjacent untreated backwater. The diversion of polluted runoff and the use of water control structures to maintain greater water depth were observed to be effective management tools, but the former reduces the water supply to habitats that tend to dry up and the latter reduces connectivity. Published in 2011 by John Wiley & Sons, Ltd.     

簸箕李引黄灌区水沙分布及优化调度的经验

灌区利用水沙观测所取得的资料和试验数据，运用水沙运动力学理论，总结分析和揭示了灌区水沙分布的规律和特点。在此基础上，结合灌区的实际运行情况，围绕减少骨干渠道的淤积进行探讨、研究，进而，优化水沙调度方案。该方案实施后，骨干渠道减旅伴效果明显，取得了成功的经验。     

小湾水库大坝防渗面板及其裂缝的加固处理

小湾水库大坝防渗面板整体抗渗性能差,且存在多条裂缝,通过对面板钢丝网喷涂丙乳砂浆加固处理及其裂缝修补,大坝渗漏量明显减少,且左岸上灌浆廊道内及大坝下游坝面92～93 m高程下廊道入口处原有小股射流全部消失.     

Spatio‐temporal variation of gross CO2 and CH4 diffusive emissions from Australian reservoirs and natural aquatic ecosystems,and estimation of net reservoir emissions

Carbon dioxide (CO₂) and methane (CH₄) diffusive emissions were measured during two field surveys in Queensland and Tasmania, Australia, using the floating chamber method. Bubbling and degassing emissions in 2010 were estimated in Koombooloomba Dam reservoir using only inverted funnels and gas concentrations, respectively. A total of 14 reservoirs and 16 rivers and lakes were sampled from 2006 to 2010. Spatial variation was substantial within each water body, as well as between them. The main drivers of diffusive emission variation were physiographic region and climate, with a clear demarcation being observed between diffusive emissions from tropical Queensland and temperate Tasmania, and between the humid West Coast Range (Tasmania) and dry Central Plateau (Tasmania). Higher CO₂ and CH₄ diffusive emissions were observed during the dry season, when long water residence times would promote organic matter degradation. Estimated total gross emissions, including diffusive, bubbling and degassing emissions, for Koombooloomba Dam reservoir were about 1.5 × 10⁶ t CO₂eq km² per year, or 24 × 10⁶ t CO₂eq per year. This corresponds to a plant emission factor of 3.18 kg CO₂eq MWh^?1. Using an estimate of terrestrial emissions derived from literature data for the Tully River catchment area, rough estimated net emissions from the catchment area are about 44 kt CO₂eq per year, or 5.83 kg CO₂eq MWh^?1, which is in the lower range of the studied reservoirs.