一般形式的挟沙力公式及其分析

将浑水潜流动量方程延拓到整个含沙水流水深的范围,在稳定条件下,推出平衡含沙量的表达式,在此基础上采用水流最小能耗率原理,得到一般形式的挟沙力公式,挟沙力系数与阻力系数成正比。论证了在不同条件下,公式可以与刘家驹、韩其为、维利卡诺夫、窦国仁和张瑞瑾等公式的形式一致,并指出各公式表达形式的不同是由于阻力系数与水流雷诺数的不同依赖关系导致的。从理论上说明了各公式的适用范围,其中张瑞瑾公式中的指数范围应为0.67~1,韩其为公式指数11/12即0.92对应为紊流过渡区水流流态;刘家驹公式适用于淤泥质底床,且其系数不是常数;维利卡诺夫公式和窦国仁公式适用于紊流粗糙区水流,维利卡诺夫公式的系数是相对糙率的函数,与雷诺数无关。通过河流及近岸实测资料对文中导出的公式进行了验证,结果表明计算值与实测值吻合很好。     

水流挟沙力公式的理论剖析与检验

为提升河流动力学学科水平,给学术研究及工程应用选取水流挟沙力公式提供依据,本文系统回顾典型水流挟沙力公式的研究进展,针对各公式依据的原理、推导过程、技术细节、影响因子等环节进行阐释分析,指出其亮点与不足,修正了水流挟沙力的定义。结合大量实测资料检验和公式适用性的评价,发现尽管资料率定能提高公式精度,但对于理论有缺陷的公式却不能体现河床和水流的自动调整作用。进一步分析认为,张红武挟沙力公式合理地将挟沙效率系数与水流阻力系数作为综合系数处理,能避免不少公式存在的水流挟沙力同水流阻力呈正比的理论错误,并通过挟沙系数为c(a+bS_v)^m的形式,体现了不同大小含沙量对挟沙效率的影响,能够保证公式具有普遍的适用性和高精度。     

明渠水流阻力系数计算公式分析与比较

按不同流态及流区对明渠水流阻力系数的计算公式进行了归纳和总结。以实测资料为依据,利用不同的阻力系数计算公式按明渠均匀流理论分别计算了实际输水明渠的过流能力,并将计算流量与实测流量进行对比,其相对误差在-7.9%～2.68%之间。其中,以紊流粗糙区的指数型公式和对数型公式的相对误差为小（-2.0%～2.68%）。在粗糙系数一定的条件下,不同阻力计算公式求得的阻力系数相差不大。从工程实用和计算方便的角度考虑,指数型公式较其它形式有更好的适应性,其计算的精确性往往取决于粗糙n的选择,用阻力平方区的公式计算过渡粗糙区的流量仍有较好的结果。     

低含沙量条件下张瑞瑾挟沙力公式中参数确定及其在荆江的应用

水流挟沙力公式及其参数选取的合理性,直接影响到悬沙输移及河床冲淤变形的计算精度。在少沙河流,张瑞瑾水流挟沙力公式被广泛应用,但其系数和指数在不同研究中取值差异较大。本研究首先选取长江中游相对冲淤平衡状态下的水流含沙量资料共计573组,将其近似等于水流挟沙力;然后点绘水流挟沙力和水沙综合参数的关系,从而确定参数k和m的计算关系;最后将完善后的水流挟沙力公式嵌入到一维水沙动力学模型中,模拟了长江中游荆江段2016年的水沙输移过程。计算结果表明:当挟沙力公式中参数采用计算式确定时,各水文站计算和实测含沙量平均相对误差在26%～36%之间;而这些参数取为常数时,含沙量平均相对误差范围为39～49%。因此当采用计算式确定张瑞瑾挟沙力公式中的参数时,相较于取值为常数,水沙输移过程的计算精度更高。故该方法解决了以往在低含沙量条件下不易确定挟沙力公式中关键参数的难题,提高了水沙数学模型的计算精度。     

水流挟沙力的统计理论计算方法及其应用

将水流挟沙力作为二维问题处理是水流挟沙力研究的重要方向,采用非均匀沙水流挟沙力的统计理论方法,根据泥沙状态概率和有效床沙级配,推导了悬移质挟沙力、推移质输沙率和推悬比统计理论公式,利用黄河下游水沙资料对公式进行验证,并与半经验悬移质挟沙力和推移质输沙率公式进行计算对比验算。计算结果表明,采用统计理论公式计算中、低含沙水流非均匀沙悬移质挟沙力较为准确,统计理论方法计算的推悬比较为稳定,黄河下游底悬比在0.06~0.11之间变化,可以采用统计理论方法的推悬比公式计算黄河下游的漏测底沙量。     

非均均沙水流挟沙力公式的初步研究

本文以“制紊假说”为理论基础，从能量平衡出发，考虑了浑水相对粘滞性、上游来水来沙条件及床沙级配等因素对水流挟沙力的不同影响，建立新的非均匀沙分组水流挟沙力公式。收集天然河道实测水文资料对公式中的系数进行率定，并验证所建立的公式，结果表明，使用本文建立的非均匀沙流挟沙力计算公式。能计算一般含沙量及高含沙水流的挟抄能力，准确性较高。     

基于两相流模式的水流挟沙力研究

水流挟沙力是泥沙研究中一个重要课题,是指在一定水流和边界条件下单位水体能够输移的饱和含沙量。当水流挟带的泥沙量与挟沙能力匹配时,河床不冲不淤;当水流挟带泥沙量与挟沙能力不匹配时,水中泥沙将与河床泥沙发生动态交换,床面淤积或冲刷,对河流床面高程产生影响。作者从考虑悬移质含沙浓度的水沙两相流基本方程出发,导出两相流瞬时能量方程并由此建立新型水流挟沙力公式,收集水流挟沙力水槽试验资料对公式中的系数进行率定。采用另外一些水槽试验资料及河流观测资料对所推求挟沙力公式进行验证,结果表明本文建立的水流挟沙力公式对低含沙水流有较高的适用性。     

长江下游河道不同时段水流挟沙力探讨

长江下游河道上起安徽省池州市梅埂(大通),下迄江苏省江阴市鹅鼻咀,属于分汊型河道,干流长约694 km.张瑞瑾水流挟沙力公式形式简单,计算方便,但式中的参数k、m确定比较困难.根据大通水文站多年来实测水文泥沙资料,推导出了长江下游河道在汛、枯期张瑞瑾水流挟沙力不同的表达式.同时,通过分析认为划分长江下游悬移质中床沙质和冲泻质的分界粒径以泥沙粒径级配曲线下脚拐点为宜.     

黄河水流挟沙力公式的验证

在评述已有水流挟沙力公式验证资料选取方法的基础上，从河床变形的基本概念出发，提出了天然河道强烈冲淤的判别指标。采用该指标选取水流挟沙力公式验证资料，对各家公式验证结果进行了相关性分析和误差分析。结果表明，6组代表性水流挟沙力公式中，张红武公式的计算值与验证资料最为接近，因此建议分析河床演变和数值模拟时选用该水流挟沙力公式。     

水流挟沙力公式检验方法的评价

由于水流挟沙力公式众多,对水流挟沙力公式的检验显得尤为重要。本文对水流挟沙力公式的检验方法进行了评述,并利用实测资料及有关计算公式,对常用的几种检验方法进行了比较分析。结果表明,对于相同检验资料,不同检验方法得到的结果并不相同。产生差异的主要原因有两点：其一,不同检验方法考虑的侧重点不同 其二,差别较大的检验资料对检验结果的影响权重不同。目前,建议同时运用相关系数法和集中系数法综合检验水流挟沙力公式。     

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.     

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. 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.     

库水波动下库岸边坡地下水浸润线解析解及误差分析

解析法是库岸边坡地下水浸润线计算中便于实际应用的方法,但该方法须基于若干假定并对潜水运动基本方程线性化后才能求解。针对各假定和线性化过程建立不同的地下水渗流数学模型,用解析法和有限元法解答上述数学模型,分析各误差大小及其规律。结果表明：库岸垂直处理带来的误差要小于方程线性化处理和不考虑非饱和渗流带来的误差,而且它们都随渗透系数变大而减小;在三峡库区库水调度情况下,假定库水位等速变化带来的误差对大多岸坡而言可以忽略;计算库岸边坡地下水浸润线时,解析法只适用于水位变化幅度相比含水层厚度较小,且几何边界规则、岩土结构简单、岩土体渗透性较好时的情况。     

Changes in Summer Irrigated Crop Area and Water Use in Southeastern Turkey from 1993 to 2002: Implications for Current and Future Water Resources

Changes in summer irrigated cropland acreage and related water use are estimated from satellite remote sensing and ancillary data in semi-arid Southeastern Turkey where traditionally dry agricultural lands are being rapidly transformed into irrigated fields with the help of water from the Euphrates-Tigris Rivers. An image classification methodology based on thresholding of Landsat NDVI images from the peak summer period reveals that the total area of summer irrigated crops has increased three-fold (from 35,000 ha to over 100,000) in the Harran Plain between 1993 and 2002. Coupled analysis of annual irrigated crop area from remote sensing and potential evapotranspiration based estimates of irrigation water requirements for cotton indicate a corresponding increase in agricultural water use from about 370 million cubic meters to over one billion cubic meters, a volume in accordance with the state estimates. These estimates have important implications for understanding the rapid changes in current agricultural withdrawals in Southeastern Turkey and form a quantitative basis for exploring the changes in future water demands in the region. For example, expansion of irrigated lands have led to a steady decrease in potential evaporation due to increased roughness and decreased humidity deficit in the Harran Plain. Assuming that the changes in future evaporation conditions will be of similar nature, water use for irrigation is expected to decrease over 40 percent in future irrigation sites. Incorporating this decrease in overall planning of the irrigation projects currently under construction should lead to improved management, and by extension, sustainability of water resources in the region.     

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.