大坝安全评价模型与预警系统试验研究

根据大坝安全监测发展的需要,开展了大坝安全评价模型与预警系统的研究。安全评价模型采用物理模型。该系统在湖北省英山县张家咀水库大坝安全监测中得到应用,运行结果表明,系统操作简便、显示直观,能实时分析和评价大坝安全。     

基于灰色尖点模型的混凝土坝裂缝转异判据研究

大坝混凝土裂缝稳定性分析是大坝安全监测的一项重要研究内容。将传统统计模型与突变理论相结合，利用传统的统计模型方法提取裂缝的时效变形，在此基础上建立裂缝的灰色尖点突变模型，得到了裂缝的转异判据。以两个大坝工程为例，利用所提出的裂缝转异判据研究了大坝裂缝的稳定性。研究结论与实际监测情况相吻合，证明了该方法的有效性。     

飞来峡大坝变形性态分析与预报模型研究

通过对飞来峡大坝的水平位移进行分析，建立相应的统计模型，并通过统计模型与BP神经网络模型进行比较，建立相应的预报模型，为飞来峡大坝的安全监测提供依据．通过分析比较得到结论：飞来峡大坝目前变形性态正常，水平位移年变幅主要受温度荷载的影响，BP神经网络模型虽然拟合精度较统计模型高，但是其预测能力并不优于统计模型，而且统计模型能对监测数据作分解和成因解释，所以采用统计模型对飞来峡大坝建立了预测模型。     

大坝安全监测统计模型的精度和实效

大坝安全监测资料综合分析是大坝安全监测工作重要组成部分，综合分析包括各种定性、定量的分析，而定量分析中多元逐步回归统计模型分析应用最为广泛。统计模型的组成一般包括水压分量、温度分量、降水分量和时效分量，模型建立是否精确直接影响到回归模型的精度和实效，温度因子、降水因子、时效因子的合理选用对回归模型精度有较大影响。针对不同类型大坝各个阶段运行情况，优选多种函数的组合作为模型的降水、时效等因子，通过多元逐步回归可获得较理想的效果，提高统计模型的精度和实效。图4幅。     

中低混凝土重力坝位移监测模型因子探讨

位移监测统计模型在大坝安全监测中应用已久,但其分析模型的选取存在多样性。列出了常见混凝土大坝监测分析过程中模型因子的多种形式,并对其进行了分析比较。同时,结合工程实例,对中低混凝土重力坝位移监测回归分析中模型因子的选取提出了参考性意见。     

茅坪溪土石坝安全复核

利用施工期的现场监测资料，应用非线性粘弹性有限元仿真分析，对茅坪溪土石坝进行了安全复核。采用邓肯E-μ模型作为坝体填料的本构关系模型，沥青混凝土材料参数根据监测资料反演求得。大坝的安全复核分析结果揭示了分区填筑的高沥青混凝土心墙的变形和应力特性。结论认为：水库蓄水后沥青混凝土心墙不会产生水力劈裂，大坝是安全的。     

浅析组合模型在大坝安全监测中的应用

文中简要阐述了几种组合模型在水库大坝安全监测与管理中的应用,通过线性组合模型及非线性组合模型的分析,针对大坝安全指标参数存在相关性以及因变量随时间城变化等问题,详细论述了建立组合模型,解决上述问题的方法,对大坝的长期安全运行管理有一定的借鉴作用.     

大坝变形监控数据处理的粗差识别方法及应用效果分析

正大坝安全监控的核心就在于通过各种监控理论与方法对监测资料进行分析,建立各类监控模型及监控指标,据此定量分析大坝及坝基的安全状态,监控大坝的安全运行,使大坝在安全运行的前提下充分发挥工程效益。大坝安全监测资料是大坝运行状态的直接反应,监测值的变化与大坝运行的环境荷载以及大坝本身结构形态有关,同时监测系统的稳定性也是重要的影响因素。大坝监测数据的异常一般由结构形态变化、环境量异常、系统改造、人为误测、误计或系统故障等     

基于领域驱动设计的大坝安全监测信息系统

针对传统数据驱动开发模式的局限性,提出通过领域驱动设计,合理分离大坝安全监测的领域知识,用软件开发人员和大坝安全监测专家都能理解的统一模型表达业务逻辑,使大坝安全监测信息系统中的模块耦合度降低,核心业务脉络清晰,更好地适应需求的变更和功能的扩展。     

某大坝安全监测资料分析研究

正确地预报大坝安全监测量,对指导大坝安全运行和辅助决策具有重要的作用。文中在分析传统的大坝监控统计模型基础上,将无线传感器网络,自回归模应用于大坝安全监测资料分析上,以解决日益突出的大坝安全问题,大坝安全监测资料分析及安全监测模型的建立是安全监测工作的最终价值体现。     

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.     

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.     

Serial discontinuities in a Rocky mountain river. II. Distribution and abundance of trichoptera

River regulation in the headwaters and middle reaches of the Gunnison River, Colorado, significantly altered distributions and abundances of Trichoptera fauna. Twenty-five species were collected from mainstream samples, with the greatest species richness occurring at an unregulated, rhithron segment above the central reach dams. At sites immediately below the three hypolimnial-release dams and a reregulation dam, species richness was reduced 35–90 per cent and abundance > 95 per cent. Net-spinning caddisflies were the dominant trichopterans at unregulated sites; Arctopsyche grandis in the upper reaches (218 organisms, 586 mg dry mass m^?2) and Hydropsyche cockerelli, H. occidentalis and Cheumatopsyche pettiti in the lower river (9041 total organisms, 6621 mg m^?2), downstream from the last dam. The observed distributional pattern of low trichopteran densities in dam tailwaters and high hydropsychid densities at sites 60–80 km below the central reach dams is a classic expression of continuum resets and adjustments in response to stream regulation as predicted by the Serial Discontinuity Concept.     

Surveying for Water Resources

Abstract

A professional Land Surveyor (Geomatician) describes the Hydrogeologists' survey requirements of a major water resources assessment for the government of The Sultanate of Oman (1992 to 1996). The need for objective specifications is stated. Specialist terms like geoid, spheroid, Mean Sea Level are explained and how to relate spheroidal levels to the geoid. Methods like traditional survey, satellite survey, and photogrammetry are introduced. The paper encourages coordinated working for the benefit of water resource assessment and recommends employment of the professional land surveyor for major studies.     

The Impact of Economic Development on Water Pollution: Trends and Policy Actions in Malaysia

The paper examines the impact of development activities on water pollution in Malaysia. Hence, the main objective of this paper is not just to examine the trends of development-induced water pollution around the region of the country but to know where the problems are and the policy measures taken by the government. It evaluates the probable causative relationship between problems introduced due to technology employed in water pollution control and governmental policy measures. It examines the relationship between development indicators as sources of pollution and polluted rivers over a period of 12 years. The findings of the paper have shown that despite the policy enforcement actions against the identified sources of water pollution, all the three development indicators (chosen based on those identified sources) still accounted for high percentage of river pollution in Malaysia. The findings of the paper were used to identify the central fact of the location of the problem. Some crucial conclusions of where the problems likely to be, as reflected in the findings, are: (a) the issue of interactive-effects between pollutants that many policy-makers are not aware of. This is when policy measures concentrate only on one source of water pollution; (b) the enforcement strength and/or effectiveness of policy measures themselves; (c) financial constraints to invest in appropriate technology especially sewerage systems for controlling human source of water pollution in the country; as well as those confronting small polluting industries (d) finally, lack of cooperation between government and private business firms to comply with regulatory policies for water pollution control.     

浅淡溢洪道改扩建方案与选择

溢洪道改扩建和进行溢洪道方案布置，要择优选取溢洪道进口型式、防冲消能工，以使其工程量省、施工快、运行管理方便     

Intangible Flood Damage Quantification

Flooding is a natural disaster that may cause tremendous tangibleand intangible damage to the national economy. The tangible damage assessment, i.e. the monetary value of all direct and indirect physical damages, has already been studied, whileintangible damages have not yet been taken into account. Thisarticle, therefore, is the first systematic attempt to assess bothtangible and intangible damages. The new proposed Anxiety-Productivity and Income Interrelationgship Approach (API) has been developed to quantify the intangible damage in monetary terms. The Bangkok area has been selected as the research area because several severe flood events have occurredthere over the last two decades. The 1983 Bangkok flood caused 6600 million baht in damage, according to estimates by the National Statistical Office (NSO). This article examines the totalflood damage (including the intangible damage) at different flood magnitudes. Case studies with and without flood mitigation projects are studied and compared. Furthermore, thisarticle also discusses the improvements over the conventional approach offered by the new API methodology.     

Seasonal variation in nutrient retention during inundation of a short‐hydroperiod floodplain

Floodplains are generally considered to be important locations for nutrient retention or inorganic‐to‐organic nutrient conversions in riverine ecosystems. However, little is known about nutrient processing in short‐hydroperiod floodplains or seasonal variation in floodplain nutrient retention. Therefore, we quantified the net uptake, release or transformation of nitrogen (N), phosphorus (P) and suspended sediment species during brief periods (1–2 days) of overbank flooding through a 250‐m floodplain flowpath on the fourth‐order Mattawoman Creek, Maryland U.S.A. Sampling occurred during a winter, two spring and a summer flood in this largely forested watershed with low nutrient and sediment loading. Concentrations of NO increased significantly in surface water flowing over the floodplain in three of the four floods, suggesting the floodplain was a source of NO. The upper portion of the floodplain flowpath consistently exported NH, most likely due to the hyporheic flushing of floodplain soil NH, which was then likely nitrified to NO in floodwaters. The floodplain was a sink for particulate organic P (POP) during two floods and particulate organic N and inorganic suspended sediment (ISS) during one flood. Large releases of all dissolved inorganic N and P species occurred following a snowmelt and subsequent cold winter flood. Although there was little consistency in most patterns of nutrient processing among the different floods, this floodplain, characterized by brief inundation, low residence time and low nutrient loading, behaved oppositely from the conceptual model for most floodplains in that it generally exported inorganic nutrients and imported organic nutrients. Published in 2007 by John Wiley & Sons, Ltd.     

Experience in the Introduction of Steam-Water-Oxygen Cleaning, Passivation, and Preservation at the TÉTs-23 Cogeneration Plant of the Mosénergo Company

Conditions of the process of steam-water-oxygen cleaning, passivation, and conservation (SWOC, P, and C) of internal heating surfaces of the boiler and the high-pressure feed heater (HPFH) piping over the steam side are presented. The process produces partial cleaning of the internal heating surfaces from scale and yields a corrosion-resistant protective film that hinders corrosion processes both in the operation of the boiler and in the idle period.     

钢筋混凝土三点弯曲梁断裂韧度计算模型

基于虚拟裂缝模型,针对钢筋混凝土试件在三点弯曲作用下开裂截面的受力特征,在合理假定的前提下,给出了一种计算钢筋混凝土三点弯曲梁的失稳断裂韧度的解析方法。然后,应用该方法计算了初始缝高比 α₀（初始裂缝长度与试件高度的比值）分别为0.2,0.3,0.4,0.5的三点弯曲试件的最大荷载和临界有效裂缝长度,进而求得了钢筋混凝土三点弯曲梁的失稳断裂韧度。通过对计算结果与试验数据的误差分析,发现失稳断裂韧度最大误差为4.915%,说明这种方法可以较为准确地预测三点弯曲梁的失稳断裂韧度。在此基础上研究了初始缝高比 α₀对失稳断裂韧度的影响,发现失稳断裂韧度基本上不随 α₀ 变化,失稳断裂韧度可以作为材料常数,应用于裂缝扩展状态的判断。