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基于长江中游四大家鱼发江量历次调查数据,采用宜昌站作为长江中游水文情势变化分析的控制站,基于其1900~2004年共105年的日径流资料,采用每年5~6月涨水过程数、总涨水日数、平均每次涨水过程日数等3项生态水文指标,分析了四大家鱼发江量与3项生态水文因子的变化关系,认为产卵场所处江段每年5~6月的总涨水日数是决定家鱼苗发江量多寡的一个重要环境因子。根据IHA方法,对宜昌站105年来的生态水文指标分析表明,长江宜昌站生态水文过程的改变并不明显,5~6月总涨水日数变化趋势不显著,显示长江中游影响四大家鱼苗发江量的生态流量过程改变不明显,与前人得出的葛洲坝枢纽修建后四大家鱼的产卵条件和卵苗江汛规律没有变化这一认识一致。但是,随着三峡水库的运行,下游河道的生态环境流量过程会有较大改变,本文建议三峡水库的调控以保障长江中游每年5~6月的总涨水日数维持在22.1±7.2范围内为生态水文目标,即可从生态环境流量过程方面补偿水利工程对中游四大家鱼鱼苗发江量的影响。  相似文献   

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Abstract

In Europe the implementation of the Water Framework Directive (WFD) will have major implications for water resources management. Part of the Directive requires Member States to implement a comprehensive system of controls (licences) on the allocation and abstraction (withdrawal) of surface and groundwater resources. This paper describes the development of a procedure to help assess and set abstraction licences for agricultural irrigation. The methodology is described with reference to Scotland, a country with limited abstraction control previously and where irrigation is supplemental to rainfall. The methodology combines spatial climatic information using a Geographical Information System (GIS) with data derived from a water balance computer model. The procedure enables the volumetric irrigation demand in a ‘design’ dry year for a given site to be estimated, taking into account local variations in climate, soil type, land use and irrigation practices. The approach provides a scientifically robust framework to allow the regulatory authority to assess the ‘reasonable’ water requirements of individual irrigators and hence develop allocations to satisfy the range of competing demands (e.g. agriculture, industry, and environment) on water resources. The methodology is applicable in other temperate countries where water abstraction controls are required and where appropriate datasets are available. The application of the procedure and its methodological limitations are described.  相似文献   

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There is currently debate within the international hydrological community on whether hydrological science should give priority to providing measurements, knowledge, and understanding pre-determined as being needed by stakeholders, or priority to more basic enquiry-driven science that will stimulate the continued health and growth of hydrology as an important Earth science discipline. Two recent major international initiatives in hydrology reflect these two perspectives. One, the Hydrology for the Environment, Life, and Policy (HELP) program, is primarily fostered by UNESCO-IHP and is focused on stimulating the stakeholder-driven hydrological science required in specific catchments that have become members of a global network. The second, the decade on Prediction in Ungauged Basins (PUB), which is appropriately managed by IAHS, is primarily driven by scientific enquiry and is focused on creating new scientific methods and understanding, albeit with practical application ultimately in mind. This paper summarizes the nature, origins, growth, and progress of these two international programs but also describes the subtly different approach that has been adopted by the U.S. National Science Foundation's (NSF's) Center for Sustainability of semi-Arid Hydrology and Riparian Areas (SAHRA). NSF is a federal agency whose primary goal is to ‘enable the future’ by stimulating novel science. Because SAHRA is a federally-funded entity supported by an agency with this goal, the Center clearly cannot operate in stakeholder-driven, response mode in competition with the already effective private U.S. consultancy industry. Nonetheless, SAHRA's mission is to create knowledge and build understanding that will enhance the prospects of sustainable water management in semi-arid regions, especially the southwestern U.S. To resolve this apparent conflict, SAHRA looks ahead to future stakeholder needs and builds its research agenda around selected critical stakeholder-relevant questions that require substantial and sustained investment in basic, multidisciplinary, enquiry-driven science. This paper describes SAHRA's approach and reports on associated research and outreach activities.  相似文献   

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Predominant age-groups in the Lake Erie freshwater drum Aplodinotus grunniens population were 3, 4, and 5 as determined from gill net, trap net, bottom trawl, and midwater trawl samples. Age and growth calculations indicated that females grew faster than males. However, the length-weight relation did not differ between sexes and was described by the equation: log W = ?5.4383 + 3.1987 log L. Some males became sexually mature at age 2 and all were mature by age 6. Females matured 1 year later than males. Three sizes of eggs were present in ovaries; the average total number was 127,000 per female for 20 females over a length range of 270 to 478 mm. Seasonal analysis of the ovary-body weight ratio indicated that spawning extended from June to August. A total annual mortality rate of 49% for drum aged 4 through 11 was derived from catch-curve analysis. Freshwater drum were widely distributed throughout Lake Erie in 1977–1979, the greatest concentration being in the western basin. They moved into warm, shallow water (less than 10 m deep) during summer, and returned to deeper water in late fall. Summer biomass estimates for the western basin, based on systematic surveys with bottom trawls, were 9,545 t in 1977 and 2,333 t in 1978.  相似文献   

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在总结水-能源-粮食纽带关系研究中, 使用频率较高或潜力较大的 8 种水-能源-粮食纽带关系定量研究方法为: 水-能源-粮食纽带关系工具 2.0( WEF Nexus Tool 2.0) ; 生命周期评价( LCA) ; 可计算的一般均衡模型( CGE) ; 系统动力学模型( SD) ; 气候、土地、能源与水资源策略( CLEWS) ; 基于社会生态系统代谢的多尺度综合评价( MuSIASEM ) ; 市场配置/ 市场配置系统集成模型( MARKAL/ TIMES) 和水资源评价规划模型-长期能源替代规划系统 ( WEAP2LEAP) 。通过总结各研究方法的产生、发展及特性, 并引用案例讨论其适用范围, 分析其优缺点和在使用 时需要注意的问题。在此基础上, 对未来水2能源2粮食纽带关系定量研究方法的发展趋势进行讨论, 认为伴随可持 续发展问题关注度的上升与水-能源-粮食纽带关系内在机理的挖掘, 未来的水-能源-粮食纽带关系定量研究方法将 更加注重量化的精确性和数据的互通以及跨学科研究和多方法的耦合。本文可为水-能源-粮食纽带关系定量研究方法的选择和更新优化提供参考。  相似文献   

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Ecologists estimate vital rates, such as growth and survival, to better understand population dynamics and identify sensitive life history parameters for species or populations of concern. Here, we assess spatiotemporal variation in growth, movement, density, and survival of subadult humpback chub living in the Little Colorado River, Grand Canyon, AZ from 2001–2002 and 2009–2013. We divided the Little Colorado River into three reaches and used a multistate mark‐recapture model to determine rates of movement and differences in survival and density between sites for different cohorts. Additionally, site‐specific and year‐specific effects on growth were evaluated using a linear model. Results indicate that summer growth was higher for upstream sites compared with downstream sites. In contrast, there was not a consistent spatial pattern across years in winter growth; however, river‐wide winter growth was negatively related to the duration of floods from 1 October to 15 May. Apparent survival was estimated to be lower at the most downstream site compared with the upstream sites; however, this could be because in part of increased emigration into the Colorado River at downstream sites. Furthermore, the 2010 cohort (i.e. fish that are age 1 in 2010) exhibited high apparent survival relative to other years. Movement between reaches varied with year, and some years exhibited preferential upstream displacement. Improving understanding of spatiotemporal effects on age 1 humpback chub survival can help inform current management efforts to translocate humpback chub into new locations and give us a better understanding of the factors that may limit this tributary's carrying capacity for humpback chub. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.  相似文献   

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淮河治理与河湖江海的关系   总被引:1,自引:1,他引:0       下载免费PDF全文
根据淮河近千年演变记录、近百年实测的河床演变资料以及治淮的经验教训,论述黄河夺淮使淮河中下游发生本质性变化,加重了洪涝灾害和治理的难度,治淮不仅要研究淮河自身,还应研究和处理淮河与黄河、洪泽湖、长江和大海的关系。认为保留洪泽湖一定的蓄水功能,实施河湖分开,扩大入海通道,消除洪泽湖作为中游侵蚀基准面的负面效应,利用疏浚和溯源冲刷调整淮河中游河床纵剖面等措施,是提高已有治淮工程防洪标准、减轻洪涝灾害的治本方向。  相似文献   

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We measured patterns of river channel migration and cutoff between 1904 and 1997 on a 160 km meandering alluvial reach of the Sacramento River by intersecting a sequential set of river channel centrelines mapped from a field survey and aerial photography. We identified approximate dates and locations of cutoffs and quantified cutoff dimensions. Twenty‐seven chute and 11 partial cutoffs occurred over this 93‐year time interval, with an average of one cutoff approximately every 2.5 years or 0.0029 cutoffs per kilometre per year. The average rate of lateral channel change was over the study period was 5.5 ± 0.6 m year?1 (approximately 0.02 channel widths per year) due to progressive migration and cutoff combined. An average of 5% of the total channel length moved laterally via chute cutoff at a rate of 22.1 ± 3.3 m year?1 versus 94% of channel length that moved via progressive migration at a rate of 4.7 ± 0.5 m year?1. The remaining 1% of channel length migrated via partial cutoff at a rate of 13.0 ± 2.8 m year?1. Although channel cutoff was less predominant mode of channel change than progressive migration in terms of channel length, an average of 20% of the total floodplain area change between successive centrelines was attributable to cutoffs. Peak cutoff frequency was concentrated temporally between 1964 and 1987 and was also spatially clustered in specific active sub‐reaches along the valley axis over the entire study period. We hypothesize that the probability of channel cutoff is a function of both channel geometry and discharge. Bends that experienced chute cutoff displayed an average sinuosity of 1.97 ± 0.1, an average radius of curvature of 2.1 ± 0.2 channel widths and an average entrance angle of 111 ± 7°, as opposed to average values for bends migrating progressively of 1.31 ± 0.01, 2.8 ± 0.1 and 66 ± 1°, respectively. The sinuosity of Sacramento River bends experiencing chute cutoff appears to have been consistently declining from 2.25 ± 0.35 channel widths in 1904 to 1.54 ± 0.23 channel widths in 1987. We hypothesize that this trend may be due in part to the influence of land‐use changes, such as the conversion of riparian forest to agriculture, on the ‘erodibility’ of bank and floodplain materials. For the post‐dam flow regime (1937 on), cutoff frequency was significantly correlated with an estimate of cumulative overbank flow. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

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今天《河北水利水电技术》期刊创刊25周年出刊100期之际,我代表省水利厅向《河北水利水电技术》全体同仁表示衷心的祝贺,并向支持本刊的各级领导致以崇高的敬意。向多年来热爱本刊的同行专家、读者和作者、历届编委以及曾在本刊工作过的同志致以由衷的谢意。《河北水利水电技术》原名《海河科技》,创刊于1977年11月。1992年更名《河北水利水电技术》,并由内部发行变更国内外公开发行,是持有国家统一刊号和国际刊号的技术性期刊。创刊25年来,《河北水利水电技术》与我省水利事业息息相关,她真实地记录和见证了我省2…  相似文献   

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结合潮州供水枢纽地质条件及枢纽的特点,介绍了潮州供水枢纽西溪拦河水闸变形系统的布置、监测技术及数据处理方法。  相似文献   

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In the Ministry of Power and Electrification of the USSR

Design, construction, and operation chronicle  相似文献   

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