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101.
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三峡水库动态汛限水位与蓄水时机选定的优化设计 总被引:16,自引:2,他引:14
阐述了三峡水库运行初期的调度规则,建立了实时调度模型。提出了防洪、发电和航运等指标体系,在此基础上,建立了用于动态汛限水位和蓄水时机优化的混合规划数学模型,并设计了一种混合编码方式,运用遗传算法对该模型进行优化求解。利用宜昌站1882~2001年实测日流量资料进行模拟优化,生成了一系列非劣解;然后运用模糊决策的方法,得到了相对合理的动态汛限水位与蓄水时机方案。结果表明,优化设计能权衡防洪与兴利之间的关系,充分挖掘汛初与汛末的潜力,提高三峡水库运行初期的综合效益。 相似文献
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在高压厂用电系统中保护真空断路器操作过电压有几种方式,本文提出在工程设计中采用何种保护方式的建议。 相似文献
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地下水的合理开发利用在南水北调中的作用 总被引:11,自引:1,他引:10
张蔚榛 《南水北调与水利科技(中英文)》2003,1(4):1-7
在系统阐述地下水资源概念和地下水含水层特点的基础上,分析了南水北调受水区地下水开采现状,探讨了解决城市和农村地下水超采的措施,利用地下水超采形成的地下库容调蓄当地降雨径流和引江水、合理开发利用地下水提高水资源利用率和利用改造咸水、防止土壤盐碱化等在南水北调中的作用。 相似文献
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调水工程对环境利弊影响综合分析 总被引:13,自引:3,他引:10
介绍古今中外主要的跨流域调水工程 ,着重进行了跨流域调水对环境利弊影响分析 ,并列举国外已建同类工程所发现的重大问题。阐述了南水北调工程的紧迫性和保护生态环境的重要性 ,建议采取与跨流域调水并行不悖的节水和治污措施 ,如 :流域性农业改革 ,工业用水资源化 ,城市污水再生化 ,城乡囤积雨水 ,调整水价 ,运用经济杠杆规律节流等。最后指出 ,跨流域调水是水资源优化配置和可持续利用的战略措施 ,它的实施是以水权为基础的。水资源是有价值的商品 ,水资源和水权的有偿交易 ,将形成水交易市场 相似文献
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《Journal of Great Lakes research》1999,25(3):468-481
A procedure for producing daily cloud-free maps of surface water temperature in the Great Lakes has been developed. It is based on satellite-derived AVHRR (Advanced Very High Resolution Radiometer) imagery from NOAA's CoastWatch program. The maps have a nominal resolution of 2.6 km and provide as complete as possible coverage of the Great Lakes on a daily basis by using previous imagery to estimate temperatures in cloud covered areas. Surface water temperature estimates derived from this procedure compare well with water temperatures measured at the eight NOAA weather buoys in the lakes. The mean difference between the buoy temperature and the satellite-derived temperature estimates is less than 0.5°C for all buoys. The root mean square differences range from 1.10 to 1.76°C.As one example of the possible applications of this product, the daily surface water temperature maps for 1992 to 1997 were analyzed to produce daily estimates of average surface water temperature for each lake. Results are compared to the long-term (28 year) mean annual cycle of average surface water temperatures. The average surface water temperatures vary from as much as 4°C below climatology in 1993 to 2 to 3°C above climatology in 1995. The new analysis procedure also provides a more realistic depiction of the spatial distribution of temperature in the springtime than the climatological maps. 相似文献
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Colour aerial photography and multi‐spectral imagery acquired from airborne platforms for the River Tummel, Scotland, was used in conjunction with field survey to assess the feasibility of monitoring hydromorphology and human alteration within the river corridor. The study was undertaken to investigate the possibility of remotely sensing the physical status of a nation's rivers at the national scale to comply with the requirement of the European Water Framework Directive. Visual assessment and unsupervised and supervised automated classifications of the imagery were undertaken and compared with field survey data. In the absence of overhanging vegetation canopies most features above the water line of interest were visible on the imagery. Below the water line, morphology and substrate composition together with bank materials on vertically cut banks are less easily detected. The overall accuracy of automated classification procedures, compared to field survey, was 60% for the colour aerial photography and 68% for the multi‐spectral imagery. Supervised classification was superior to unsupervised classification procedures. Sun glint on water surfaces and shadows caused by high banks, trees and buildings were observed as the cause of most misclassification of features. Overall, the study demonstrates that remotely sensed digital imagery has the potential to allow panoptic mapping of river hydromorphology and human impacts. The possibilities and constraints, in light of the findings of this study, are discussed. In the context of new legislation which requires environmental protection agencies to have robust tools for monitoring the physical status, as part of meeting the objective of good ecological status, of rivers across an entire nation, remote sensing appears to provide a way forward. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献