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1.
During the past 100 years, most large rivers in North America have been altered for flood control, hydropower, navigation or water supply development. Although these activities clearly provide important human services, their associated environmental disturbances can profoundly affect stream‐dwelling organisms. We used dynamic multi‐species occupancy models combined with a trait‐based approach to estimate the influence of site‐level and species‐level characteristics on patch dynamic rates for 15 darter species native to the Elk River, a large, flow‐regulated Tennessee River tributary in Tennessee and Alabama. Dynamic occupancy modelling results indicated that for every 2.5 °C increase in stream temperature, darters were 3.94 times more likely to colonize previously unoccupied stream reaches. Additionally, large‐bodied darter species were 3.72 times more likely to colonize stream reaches compared with small‐bodied species, but crevice‐spawning darter species were 5.24 times less likely to colonize previously unoccupied stream reaches. In contrast, darters were 2.21 times less likely to become locally extinct for every 2.5 °C increase in stream temperature, but high stream discharge conditions elevated the risk of local extinction. Lastly, the presence of populations in neighbouring upstream study reaches contributed to a lower risk of extinction, whereas the presence of populations in neighbouring downstream study reaches contributed to higher rates of colonization. Our study demonstrates the application of a trait‐based approach combined with a metapopulation framework to assess the patch dynamics of darters in a regulated river. Results from our study will provide a baseline for evaluating the ecological consequences of alternative dam operations. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
2.
基于Google Earth的河流模拟地形前处理新方法 总被引：2，自引：0，他引：2
本文首先阐述了河流模拟地形前处理的常规方法,然后探讨了利用Google Earth进行地形初步处理的新方法,介绍了基于Google Earth的高程数据提取技术,说明了部分Google Earth API接口的功能,指出并解决了其中一类API调用过程中存在的问题。研究证明,利用Google Earth进行河流模拟地形初步处理,可以显著提高河流模拟过程中的地形处理效率。 相似文献
3.
J. B. Atha 《河流研究与利用》2014,30(7):857-864
Fluvial wood has long been known to enhance stream complexity by creating aquatic habitat and by increasing complexity in channel hydraulics and morphology. Although the presence and dynamics of large wood in river floodplains have been studied in a multitude of settings due to its importance in monitoring and managing ecohydrologic systems, limitations occur when studying fluvial wood on a basin scale. I postulate that with the employment of Google Earth, satellite images may be used to identify large wood and measure floodplain width across broader spatial scales previously inhibited by expensive and incomplete geospatial data. In this study, large wood was correctly identified within the floodplain of the Queets River, Washington, USA, through Google Earth; however, correct identification within the wetted channel was only possible during low flow if at least 50% was above water level. Within the study area, fluvial channel widths are measured as well. Google Earth proves to be an effective tool to discern large wood across greater spatial scales if the high‐resolution imagery is available for the study area. Results of statistical analyses derived from the downstream hydraulic geometry of the river reveal that this channel is influenced by bankfull width, the orientation of the wood to the channel, and whether it is located on a bar or within the wetted channel. In addition, wood counts analyzed in the context of the geometry of the river indicate that the fluvial wood has an influence on overall channel behavior. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
4.
Rivers regulated by dams are typically characterized by altered biotic communities and habitat structure in downstream reaches. In the Jackson River (Alleghany Co., VA), a relatively constant flow regime below Gathright Dam and anthropogenic nutrient loading have apparently contributed to nuisance levels of periphyton (>300 mg chlorophyll a m?2). These nuisance growths cause low dissolved oxygen concentrations in the water column and altered benthic habitats in the Jackson River. The use of periodic pulsed flows has been suggested as a restoration practice that could potentially reduce periphyton biomass. We investigated the effects of increased flow on periphyton chlorophyll a (chl a), ash‐free dry mass (AFDM), % organic matter (%OM) using streamside channels in which periphyton‐colonized tiles were subjected to near‐bed velocities ranging from 20 (control) to 240 cm s?1. Analysis of variance (ANOVA) and regression were used to examine periphyton responses to velocity treatments. There was a significant decrease in chl a and AFDM, and significant increase in %OM in velocity treatments of 150, 180 and 240 cm s?1 (p < 0.001), but not in lower velocity channels. Regression analyses showed a significant positive relationship with %OM (r2 = 0.88) and significant negative relationship with chl a (r2 = 0.77) and AFDM (r2 = 0.63). Algal taxa were dominated by Cladophora glomerata, Melosira varians and Pleurosira laevis. There was a significant positive relationship between treatment velocity and % C. glomerata (p = 0.007, r2 = 0.87) as diatoms were differentially removed with increasing treatment velocity. Our results demonstrate that pulsed flows can reduce periphyton standing crops in the Jackson River, but the discharge required to achieve this reduction would probably need to produce near‐bed velocities >100 cm s?1. Further study is needed to establish specific flow targets and evaluate the direct and indirect effects of pulsed flows on ecological conditions in the Jackson River. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
5.
为解决无实测资料地区的河道地形数据获取问题,提出了一种基于Google Earth影像提取河道地形数据的方法,利用该方法提取了鉴江流域的河道地形数据并将其应用于水动力模型的构建。结果表明:利用该方法提取的河道地形数据所构建的水动力模型,其模拟过程与实际过程基本一致,其中模拟的最大、最小流量与实测对应的最大、最小流量的相对误差分别为14.3%和7.8%,流量模拟的整体相对误差为13.2%;模拟的最高、最低水位与实测对应的最高、最低水位的相对误差分别为5.5%和3.9%,水位模拟的整体相对误差为5.2%;基于Google Earth影像提取河道地形数据是解决无河道地形资料地区的一种便捷且行之有效的方法。 相似文献
6.
生态输水是干旱区内陆河流域退化生态系统恢复的主要措施,而流域下游的河水漫溢直接关系到绿洲的恢复成效。基于1987—2021年全球地表水体数据集,结合流域内自然环境和人类活动等数据,通过GEE平台构建的水体频率,即像素点在特定时间段内观测到水体的次数与总观测次数的比率,分析了黑河下游生态输水前、后河水漫溢的时空演变及其影响因素。结果表明：分水前1987—2001年正义峡、哨马营和狼心山的年均径流量分别为8.86×108、5.28×108、4.27×108 m3,分水后2002—2021年分别为11.99×108、8.12×108、6.70×108 m3,狼心山-东居延海段的年均径流量（即绿洲可利用水资源量）为6.17×108 m3,时间上主要集中在4—5和9—10月;分水后永久性水体面积逐渐增加且主要集中在东居延海,2004年后东居延海出现永久性水体,水体频率最高出现在哨马营-狼心山段河道两侧,其次是东居延海及其外围区域,东河、西河及西居延海水体频率相对较低;分水前河水漫溢主要是由自然水文过程引起的,同时也受到中游人类活动的较大影响,分水后河水漫溢与生态输水量呈显著正相关（P<0.01）,下游年蒸发量和人类活动均与河水漫溢呈显著负相关（P<0.01）。建议兴建和修缮黑河下游水利设施,改善下游河水漫溢的时空分布不均性,保障下游生态系统的健康与安全。 相似文献
7.
Nicholas Pinter James Brasington Angela Gurnell G. Mathias Kondolf Klement Tockner Geraldene Wharton Sarah M. Yarnell 《河流研究与利用》2019,35(6):768-775
Rivers flow across national borders, unfettered by political distinctions, and the ecological health of rivers is closely linked to their degree of connectivity. River research today is more global than it has ever been, but we show that river research, engineering, and management still operate within homegrown local paradigms. As a basis for this discussion, we studied the citation networks surrounding the most widely cited papers in our field, assessing the degree to which researchers have collaborated across geographical boundaries and fully drawn from the international literature. Despite gains over time, our field remains surprisingly and pervasively provincial. The likely explanation for provincial bias is that researchers are generally more familiar and comfortable with their own research methods, sites, and agendas. However, local focus has tangible consequences. For example, contrasting paradigms and differing approaches to river restoration and to flood‐risk management show that opportunities are lost when we fail to learn from the successes and failures of other regions. As we look to the future, increased engagement across political and intellectual and physical borders should propel the field of river science into new and exciting directions. 相似文献
8.
端木雪妍;拾兵 《水利水运工程学报》2025,(2):24-37
湿地植被是黄河三角洲生态系统的重要组成,然而植被分布混杂,且光谱特征相近,还有可能由于不定期被水体淹没导致同种地物之间光谱差异较大,遥感分类识别工作难度较大,效率也有待提升。基于Google Earth Engine （GEE）云计算平台,结合Harmonic Analysis of Time Series （HANTS）算法提取植被物候特征确定了植被分布提取的最优时相,利用实地勘测数据和多源遥感影像,设计了4种分类方案,采用机器学习算法实现2016—2023年各年多时相植被分类制图。分类总体精度均在93.38%以上,Kappa系数均高于0.92,其中采用面向对象分类加上雷达极化特征的方案所得分类结果精度最高,尤其是在芦苇和互花米草的区分上,精度均超过97%,碱蓬低于前两者,但精度也近92%。对多年植被时空演变特征进行分析,发现互花米草面积由35.6 km2持续增加至52.2 km2,刈割后大幅降低至不足10 km2,芦苇面积随互花米草变化呈先降后升趋势,面积最小时仅有74.3 km2,碱蓬面积波动下降;芦苇和碱蓬分布与河道走向基本一致,刈割遏制了互花米草向保护区南侧的扩张且整体清除效果较好,整体植被生长演变状况受人类活动影响较大。应用本文方法获取典型植被的分布范围,有着精确度高、运算速度快、占用内存小的优点,适用于黄河三角洲湿地植被监测,可为该地区生态保护和高质量发展提供理论依据。 相似文献
9.
Understanding of geomorphic processes and the determination of geomorphic diversity in catchments are prerequisites for the sustainable rehabilitation of river systems and for reach‐scale assessment of river health. The Ganga River system in India is a large, complex system consisting of several long tributaries, some >1,000 km, originating from 2 distinct hinterlands—the Himalaya to the north and the cratons to the south. Traversing through a diverse climatic regime across the Plain and through precipitation zones ranging from 600 mm/year near Delhi to 1,200 mm/year in the eastern plains, the Ganga River system has formed very diverse landform assemblages in 3 major geomorphic domains. We have recognized 10 different river classes for the trunk river from Gangotri (source) to Farakka (upstream of its confluence with the Brahmaputra) based on (a) landscape setting, (b) channel and active floodplain properties, and (c) channel planform parameters. The mountainous stretch is characterized by steep valleys and bedrock channels and is dominated by large‐scale sediment production and transport through hill slope processes. The alluvial part of the river is characterized by 8 different river classes of varying reach lengths (60–300 km) many of which show sharp transitions in landscape setting. We have highlighted the application of this approach for the assessment of habitat suitability, environmental flows, and flood risk all of which have been significantly modified during the last few decades due to large‐scale anthropogenic disturbances. We suggest that the diversity embedded in this geomorphic framework can be useful for developing a sustainable river management programme to “work with” the contemporary character and behaviour of rivers. 相似文献
10.
The Basic Flow is a methodology used to calculate environmental flow needs for river regulation. It has gained increased recognition in Spain for hydrological planning. It is based on the study of irregularities in hydrological series of daily mean flows using the simple moving average model as a tool to extract the relevant information. The Basic Flow Methodology (BFM), beyond providing a unique minimum flow value, constitutes a complex management proposal for regulated rivers which includes other management aspects affecting the biological functioning of a river (such as the necessity of flow variability, bankfull flows or varying flow rates) through the establishment of monthly instream flow requirements. This paper presents a practical application of the BFM in the Silvan stream, a natural mountain stream impacted by a hydroelectric regulation project. Results are discussed in terms of physical habitat created and compared to those obtained from the application of another method based on the Instream Flow Incremental Methodology, using a set of computer programs (RHYHABSIM) for physical habitat simulation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
11.
The ecosystem concept should be reappraised as a basic model for rivers, with regard for flow as an organizing variable. This would facilitate comparisons between the large rivers of humid climates, where flow regimes are comparatively regular, and those of arid and semi-arid areas, where river regimes are highly variable. Ecosystem processes might be modelled by combining the river continuum and flood pulse concepts, with refinements to accommodate a complex flood pulse (e.g. variations in stage amplitude, timing, duration, rates of rise and fall). Patch boundaries (ecotones) such as the riverine littoral zone warrant close study because they strongly influence the structure and dynamics of the ecosystem. The general model needs a quantitative basis, perhaps focused on the balance of processes involved in the physical transport and biological transformation of carbon. The ultimate test of such a model will be in its capacity to predict the effects of flow regulation. Further development, however, is limited by data. In both research and management monitoring programmes need to be established to provide information and to develop a sustained, comprehensive approach to dryland rivers as ecosystems. 相似文献
12.
介绍中国国际河流管理的现状,分析中国国际河流管理存在的主要问题,并针对这些问题提出以下建议:实现合作共享、优势互补,可持续与环保,带动区域经济发展是中国国际河流合作开发管理的宗旨;中国国际河流管理应向多边合作、区域综合合作、流域整体开发和管理的方向发展;健全、完善并创新现有与国际河流管理有关的法律法规,促使各法律法规协调运行;建立多层次、多主体参与的国际河流管理协商机制。 相似文献
13.
利用Google Earth遥感影像,测量了拉萨河流域451个局部河段的河流水面宽度,得出了10个主要河段的平均河宽。研究中,分别点绘了10个主要河段的平均河宽与5种地形结构因子(河流纵比降、弯曲度、凹度、河流上游集水面积、流域平均坡度)的相关图,采用线性函数、指数函数、对数函数以及幂函数4种函数对其进行相关性分析。结果发现,在5种因子中,河流水面宽度与上游集水面积相关性最好,当用线性函数拟合时确定性系数达到了0.81;河流的纵比降与河宽的相关性也较好,当采用指数函数与幂函数拟合时,两者的确定性系数均为0.76。研究探讨拉萨河流域河宽和地形结构因子的相互关系对认识青藏高原河流地貌特征规律以及提高无资料流域河流流量和总水量预测的能力等均有重要意义。 相似文献
14.
冲积河流航道整治线宽度的研究 总被引：4，自引：1，他引：4
作者通过回顾以往研究 ,从泥沙运动和河床演变理论出发 ,分析讨论了整治线宽度的几个概念问题 ,提出了浅滩“整治前后多年平均年内输沙总量相等”的观点 ,推导了相应的整治线宽度公式 ,并根据概化水槽试验及多条天然河流的实测资料进行验证 ,还讨论了整治线宽度公式形式、参数确定、来水来沙影响、悬沙造床情况、整治水位与整治线宽度关系等问题 ,得出了新的认识和论点。研究成果较以往研究在理论上有进步 ,为今后深入研究打下了良好的基础 ,也可供有关浅滩航道整治工程设计所参考 相似文献
15.
Floodplain waterbodies are reputed to enhance recruitment of riverine fish populations via provision of spawning and nursery habitat, refuge from floods, and increased availability of planktonic food resources compared with main river channels. Notwithstanding, there have been few parallel studies of fishes and their food resources at both main river and floodplain sites. Thus, this study investigated the 0+ fishes, zooplankton and phytoplankton (chlorophyll a) at four main river and four (man‐made) floodplain sites on the lower River Trent, England, between May 1999 and October 2004 inclusive. All sites shared the same key fish species, and there were no consistent differences in the densities, growth or condition of 0+ fishes from main river and floodplain sites. Similarly, all sites shared the same key zooplankton taxa. However, zooplankton densities, notably of large‐bodied cladocerans, and chlorophyll a concentrations, were significantly higher at floodplain sites than at main river sites. Thus, connection of man‐made waterbodies has the potential to enhance recruitment of riverine fish populations via provision of important spawning and nursery habitat, and superior feeding opportunities for 0+ fishes compared with main river channels. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
16.
The lower reaches of the River Dyje were heavily modified between 1975 and 1985. The river was straightened, isolating its meanders and reducing its length by 22%. As a consequence, the river bed showed a markedly lower diversity in both hydrological and morphological characteristics. Because the River Dyje forms the state boundary between the Czech Republic and Austria, fluvial activity of the lower reaches is excluded. Along the River Dyje an active alluvium has been preserved, with approximately 1300 hectares in the Czech Republic and somewhat less in Austria. The flow regime in the lower reaches is regulated by 19 water reservoirs and a number of fishponds, with a total capacity of approximately 45% of the annual drainage. These modifications have distinctly impacted the living conditions of the indigenous ichthyofauna. Based on the results of our ichthyological investigations from 1994 to 2000, we have recommended a number of modifications that could improve the environmental conditions for fishes: (i) controlled flooding of the alluvial meadows, aimed at creating conditions for the spawning of phytophilous fish species; (ii) restoration of permanent connections between separated river meanders and the River Dyje to increase the hydrological and morphological diversity in the river bed; (iii) creation of artificial pools in the floodplain to provide more suitable habitats for fishes. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
17.
通过自然模型实验的方法,借助模型小河模拟了自然界中顺直河道洪水情况的演变和正常情况下河流弯曲与分汊的演变过程,针对自然河流的形态特征,弯道的形成条件以及河湾的演变趋势进行了研究.实验再现了自然河流的演变过程,通过数据分析得到了自然河流的演变规律. 相似文献
18.
Mauro Carolli Francesca Gelmini Stefano Pellegrini Micaela Deriu Guido Zolezzi 《河流研究与利用》2021,37(1):17-32
We discuss the prioritization of river reaches to be selected for restoration measures under the constraints of financial resource limitation. We propose and apply a simple approach based on the quantification of major hydro‐morphological alterations and the critical comparison with locally proposed restoration actions. The available hydro‐morphological and ecological data for the approach do not go beyond the requirements posed by the implementation of the EU Water Framework and Floods Directives. We describe an example that refers to a heavily regulated Alpine river (Sarca River, NE Italy). The results indicate hydropower facilities as a key source of hydrological alteration, with sediment retention and grade control structures on lateral tributaries playing an additional relevant role in reducing sediment supply. The frequency and duration of sediment‐transporting floods have dramatically decreased, and the bed sediment composition has been markedly altered and become highly compacted. Habitat improvement has been achieved after the implementation of minimum environmental flows. The comparison between the results of the hydro‐morphological indicators and the locally proposed restoration actions highlights that reaches with lower degree of hydro‐morphological alterations do not coincide with the areas chosen for the locally planned actions, which often miss considerations of the relevant spatial scales. In a context of limited available financial resources and data compared to other flagship river restoration projects in the European Alps, the present work suggests viable options for the choice of target restoration reaches. 相似文献
19.
Water holes characteristic of the middle sections of fragmented, lowland, semi‐arid rivers act as refuge areas for biota during low flow and drought. However, river regulation and catchment development has altered the hydrological and nutrient status of these refuges. A series of artificial ponds were used to imitate these habitats and experiments were designed to determine whether stochastically fluctuating water levels with maximum amplitude of 65 cm would counteract the influence of nutrient enrichment on the growth of three key aquatic plant species. The species (Cyperus gymnocaulos, Triglochin procerum and Typha domingensis) represented different functional groups that inhabit contrasting zones across the elevation gradient. Each species was grown at a different elevation within the experiment reflecting each species' elevation preference and supplied with the equivalent to 0, 10 or 30 g N m?2 year?1. Under a static water regime nutrient enrichment doubled the total biomass of all three species. In contrast under a fluctuating water regime, nutrient addition did not influence total biomass of either T. domingensis or T. procerum and the performance of C. gymnocaulos was reduced by ca. 30%. These data suggest that if environmental flows were managed to provide a natural stochastically fluctuating water regime, this would nullify the influence of nutrient enrichment and limit the distribution and spread of invasive species such as Typha, that exists under the current altered conditions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
20.