聚合分解随机动态规划模型在梯级水库群发电调度中的应用研究

本文首先采用聚合分解思想将梯级水库群来水量和库容聚合等效为单库，从而简化水库群径流过程的描述和降低高维计算空间，使随机动态规划模型（SDP）在梯级水库群的应用中可以考虑更多的信息来提高模型效率；然后在径流预报中考虑美国全球预报系统（GFS）发布的未来10天降雨预报信息，来提高中期径流预报精度；最后在考虑径流预报不确定性的基础上建立了聚合分解贝叶斯随机动态规划模型（AD-BSDP）。同时与传统调度图、聚合来水量的随机动态规划模型（AF-SDP）和聚合来水量、库容的聚合分解随机动态规划模型（AD-SDP）进行了对比分析来验证模型的有效性，分析结果表明考虑预报信息不确定性的AD-BSDP模型比其他模型具有更高的效率和稳定性。     

基于降雨预报信息的梯级水电站不确定优化调度研究Ⅱ：耦合短、中期预报信息

基于聚合分解思想将梯级水库群聚合为“虚拟单库”,降低了随机动态规划（SDP）模型的计算量,从而使SDP模型可以考虑更多预报信息。为了更近一步充分利用预报信息和降低预报信息不确定性对调度的影响,将降雨预报和径流预报的不确定性考虑为随预见期延长而不断增加的过程。首先将浑江流域的10d预报径流划分为前5d和后5d,并将前5d预报径流视为较准确的部分,而后5d预报径流视为不确定性较大部分;然后建立短、中期径流预报信息相套接的分段聚合分解贝叶斯随机动态规划（Two-Step-BSDP,TS-BSDP）,为浑江梯级水库群制定前5d、后5d和10d的预报调度图;最后以5d为调度时段分别决策未来5d发电和10d发电计划。模拟调度结果表明,该模型中决策长度为5d的滚动决策具有更好的效果,该决策方式充分地利用了预报信息并有效地提高了发电效益。     

基于短、中期径流预报信息套接的水库群发电优化调度模型研究

在水库发电调度决策中，考虑径流预报信息是提高水库群发电效益减少弃水的有效措施。目前通过数值气象预报信息已可获得流域未来10天预报降雨量，但降雨预报信息和径流预报模型随预见期延长不确定性增加，即直接采用10天径流预报信息将会给水库发电调度决策带来较大的不确定性，而只采用预报较准确的短期预报信息又会缩短调度的预见期。因此本文首先以美国全球预报系统（GFS）发布的浑江流域未来10天预报降雨信息来预测未来前5天和后5天径流量，并将前5天预报径流视为较准确的部分，而后5天预报径流视为不确定性较大部分，然后采用聚合分解贝叶斯随机动态规划模型为浑江梯级水库群制定前5天和10天的预报调度图，最后以5天为调度时段向后滚动决策未来5天发电和10天发电计划。模拟调度结果表明该模型充分利用了预报信息，并有效提高了发电效益。     

径流贝叶斯概率预报在水库发电优化调度中的应用

为了充分考虑降雨、径流预报的不确定性和降低水库发电调度模型的复杂性,采用贝叶斯概率水文预报系统(BFS)耦合降雨预报的不确定性和径流预报模型本身的不确定性来定量描述径流预报的不确定性,发布径流确定性预报、概率预报和概率预报期望值;结合随机动态规划(SDP)模型和贝叶斯随机动态规划(BSDP)模型来制定发电调度图;以浑江桓仁水库流域为背景,采用美国国家天气局的全球预报系统(GFS)发布的10d降雨预报信息作为预报模型输入,模拟桓仁水库的发电调度过程。模拟结果表明基于径流贝叶斯概率预报的水库发电调度能有效提高水库的发电效益和保证率。     

梯级水库群联合防洪预报调度方式风险分析

目前,梯级水库群防洪调度风险的研究存在仅考虑单一风险因子或缺乏考虑防护点风险等问题。针对上述问题,在识别梯级水库群联合预报调度方式风险源和风险的基础上,建立了考虑多种不确定性影响下的水库群自身及防护点的综合风险分析模型,采用蒙特卡洛随机模拟法由上游至下游计算其风险率。昭平台-白龟山梯级水库群的实例表明,联合预报调度方式的实施不会增加额外风险。     

一种考虑径流预报及其不确定性的水库优化调度模型

鉴于纯随机径流描述或确定性径流预报的水库(群)优化调度模型,未考虑径流预报及其不确定性,导致优化计算结果与水库实际运行情况存在较大差异.本文提出了一种利用后验的径流状态转移概率和径流预报的可预测性概率来描述径流预报及其不确定性的优化调度模型.依据二滩水电站径流及其预报的实际状况,考虑不同预见期的径流预报信息,建立了考虑...     

长江上游水库群调蓄对下游电站发电能力影响分析

随着长江上游水利工程的陆续兴建投运，干流年来水量和径流年内分配过程发生显著变化，势必对下游水库群调度运行造成较大影响。以长江上游干支流水库群为研究对象，建立上游干支流水库群运行模拟模型以及金沙江下游-三峡梯级水库群联合发电优化调度模型，重点分析中长期尺度上游干支流水库群调蓄对金沙江下游-三峡梯级电站发电能力的影响。研究结果表明：上游干支流水库群调蓄极大地改变了溪洛渡及三峡水库来水年内分配，提高了枯期来水占比，进一步提高了梯级电站发电能力；丰水年条件下，梯级总发电量增加了1.22%,总弃水量减少了14.11%;枯水年条件下，梯级总发电量增加了3.16%,总弃水量减少了15.67%。     

水电站水库群防洪补偿联合调度模型研究及应用

针对具有下游防洪任务的水电站水库群，提出基于预报及库容补偿的水库群防洪补偿联合调度逐次渐进协调模型，推求水库汛期防洪库容动态控制方案。该模型运用了大系统分解协调理论及贝尔曼的逐步逼近思想，以各水库为独立的子系统建立3层递阶结构，针对库间水力、电力联系及防洪库容限制等复杂的约束条件进行不同层次的协调。模型经过多次迭代计算，得到最佳的水库群防洪库容协调方案。该模型应用于清江流域梯级水库，计算结果表明，在不降低水库及梯级原有的防洪标准前提下，能有效利用上游水布垭水库的防洪库容，分担隔河岩水库部分防洪任务，并显著提高梯级水库发电量。     

长江上游控制性水库群联合调度及水资源影响分析

针对长江上游控制性水库群联合调度问题,建立了大规模混联水库群联合优化调度模型,并提出离散微分动态规划(DDDP)和逐步优化算法(POA)相结合的混合方法,实现大规模混联梯级水库群联合优化调度问题的高效求解。在此基础上,结合流域长系列历史径流资料,进行了长江上游控制性梯级水库群调度模拟,分析了联合调度的发电效益;并在此基础上,结合相关研究成果,探究并分析了梯级水库群建成投运后,联合调度对流域水资源的影响。成果表明,梯级水库群的建成及联合调蓄对于长江中下游枯水期的流量补偿效益十分明显,供水、航运以及压咸补淡等综合效益十分显著。     

利用长期气象预报资料进行水库优化调度

黄龙滩水电厂位于汉江流域上游的堵河干流上，坝址流域面积11140km^2，多年平均径流理60．2亿m^3。利用历史资料和现有气象预报条件，建立降雨径流之间确定性模型，利用中长期降雨预报资料来推求径流，再引用动态规划法计算和制定长期调度计划，选用丰水年（2000）巫溪气象台、枯水年（1999）十堰气象台两个代表年份的预报降雨资料推求水库径流过程，应用动态规划法编制水库优化调度计划，与综合法编制的水库调度计划以及实际调度过程作对比分析。预报法编制的优化调度计划较综合法更为科学合理，能够指导生产实践。     

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.     

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.     

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.     

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.     

浅谈优化Vray渲染在制作三维场景的应用研究

用Vray三维渲染引擎来渲染三维场景,其质量和速度是由一些影响因素和参数设置决定的,不同的参数和因素,可以得出不同的三维渲染效果.因此,分析、优化三维渲染质量和速度的影响因素,正确、合理的选择参数对提高Vray最后渲染阶段的质量和速度非常重要.     

固结、渗流和沉积控制方程研究

本文从两相流体动力学的守恒方程出发，考虑固相、液相的相对运动，推导了可以考虑场的不均匀性和流体压缩性的统一形式的控制方程，并对方程所基于的物理概念和相互联系进行了必要的分析。通过对方程适当形式的表达，可导出用于大、小变形固结、渗流和沉积的简化方程，显示了在不同领域的三个理论存在一定的统一性。方程推导过程并未对本构关系加以限制，适用范围较广。依据实际问题的要求，作了不同形式的简化。     

四川省及重庆市中型水电站效益分析

该文分析了四川省及重庆市几座中型水电站的调查材料表明：四川省及重庆市中型水电站不仅在川渝主网和地方电网中起着很大的作用，并具有巨大的社会效益，同时还有综合利用效益，说明修建中型水电站的优越性．