共查询到20条相似文献，搜索用时 31 毫秒
1.
The effects of river regulation on the hydrological cycle of a river and on the respective fish assemblage may differ according to dam operation purpose and type of river analysed. To assess the spatial and temporal variation of fish assemblages and their response to the hydrological changes caused by two different types of flow regulation, we selected three sampling sites in four rivers with different levels of regulation, two in a permanent river system and another two on a temporary one, which we sampled in four different annual seasons. In the permanent system, hydroelectrical regulation decreased hydrological variability, which affected fluvial specialist species, benefitting the generalist ones, and created a more homogeneous community that presented less intra‐annual variation. In the temporary system, agricultural regulation caused an inversion of the hydrological cycle, maintaining a moderate flow volume throughout the drought period that benefited the introduced, generalist and more tolerant species. Monthly volume was recognized, in a temporal scale, as the most important hydrological feature for assemblages’ structure, predicting the intra‐annual variation of several ecological guilds. This study provides important considerations for dam management and riverine ecosystems conservation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
2.
The diversity of fish species found in warmwater stream systems provides a perplexing challenge when selecting species for assessment of instream flow needs from physical habitat analyses. In this paper we examined the feasibility of developing habitat suitability criteria (HSC) for the entire fish community of a warmwater stream using habitat guilds. Each species was placed a priori into a guild structure and habitat data were collected for depth, velocity, Froude number, distance to cover, embeddedness and dominant and subdominant substrate. Correct guild classification was tested with linear discriminant analysis for each species. Correct classification based on habitat‐use data was highest for riffle and pool‐cover guilds, whereas the fast‐generalist and pool‐run classes, the broader niche guilds, were more frequently misclassified. Variables most important for discriminating guilds were Froude number, velocity and depth in that order. Nonparametric tolerance limits were used to develop guild suitability criteria for continuous variables and the Strauss linear index was used for categorical variables. We recommend the use of a wide array of variables to establish more accurate habitat analysis. Additionally, guild HSC can be developed with similar effort to that needed to develop HSC for a small number of individual species. Results indicate that a habitat guild structure can be successfully transferred to another river basin and that habitats for a diverse fish assemblage can be adequately described by a small number of habitat guilds. This approach represents an alternative for incorporating entire fish assemblages into habitat analyses of warmwater stream systems. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
3.
大坝运行过程中泄水会对坝下游生态系统产生负面影响,体现在河道生态环境、洪泛区生态环境和河口生态环境中水文水力情势、河道形态和地貌、水质、原有生物生存和繁衍环境等发生变化,生物种类和数量减少,生物多样性降低。因此有必要对河道区、洪泛区和河口区进行水文水质监测、地下水水位监测、鱼类及水生生物监测、动植物种类和生境调查等;同时,确保大坝下游河段环境流量、制定合理的泄水调度方案和实施坝下游生态系统恢复,以期控制负面影响,使坝下游生态系统逐渐呈良性循环。 相似文献
4.
5.
Reservoirs are sometimes managed to meet agricultural and other water demands, while also maintaining streamflow for aquatic species and ecosystems. In the Henrys Fork Snake River, Idaho (USA), irrigation-season management of a headwater reservoir is informed by a flow target in a management reach ~95 km downstream. The target is in place to meet irrigation demand and maintain aquatic habitat within the 11.4 km management reach and has undergone four flow target assignments from 1978 to 2021. Recent changes to irrigation-season management to maximize reservoir carryover warranted investigation into the flow target assignment. Thus, we created a streamflow-habitat model using hydraulic measurements, habitat unit mapping, and published habitat suitability criteria for Brown Trout (Salmo trutta), Rainbow Trout (Oncorhynchus mykiss), and Mountain Whitefish (Prosopium williamsoni). We used model output to compare habitat availability across two management regimes (1978–2017 and 2018–2021). We found that efforts to minimize reservoir releases in 2018–2021 did not reduce mean irrigation-season fish habitat relative to natural flow, but did reduce overall fish habitat variability during the irrigation season compared to streamflow management in 1978–2017. Field observations for this research led to an adjusted flow target in 2020 that moved the target location downstream of intervening irrigation diversions. Using our model output, we demonstrated that moving the location of the target to account for local irrigation diversions will contribute to more consistently suitable fish habitat in the reach. Our study demonstrates the importance of site selection for establishing environmental flow targets. 相似文献
6.
7.
Water management agencies throughout Australia are attempting to find a balance between the water requirements of ecological and socio‐economic environments as part of a holistic approach to managing flow‐dependent river ecosystems. Environmental water provisions are under consideration for the Ord River in far northern Western Australia. This river has been regulated for irrigation and there are plans for substantial expansion. Like other semi‐arid and tropical rivers, however, the hydrology of the Ord River is highly variable and unpredictable, and therefore, proportionate water release strategies for the environment that are based on average monthly flows are unsuitable. Regulation continues to produce pronounced ecological changes throughout the river system as the impacts of flow regime are negated. There is a dichotomy in optimal flow regimes for the contrasting management aspirations of ecological restoration based on low seasonal flows, and the dilution flows required for the drainage of agricultural effluent. Whilst current agricultural land and water management practices continue, the two cannot coincide, and consequently, a decision should be made regarding which environmental water allocation holds the primary value. Such a decision would guide the appropriate dry season flow regime on the lower Ord River. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
8.
本文对减水河段的水力生态修复措施进行研究,包括在横断面上设置深槽和纵向上间隔一定距离设置挡水堰。以一段120m长的河段为例,对深槽和挡水堰不同组合的修复方案进行了二维水力模拟计算。根据代表鱼类对水深、流速适宜度的曲线,计算出权重可使用栖息地面积(WUA)来分析生境改善效果,同时还对影响河段沿程增温率的水力参数进行了对比分析。在河道流量为1.65m3/s（约为多年平均流量的5%）时,采用深槽修复可增加WUA约48%,在深槽基础上设一道拦水堰后共可增加WUA约84%;同时深槽还可使河流沿程增温率下降,使水温更接近减水前的状况。采用多道拦水堰有助于尽可能多地提高WUA,但拦水堰间距也不应过小,对于该河段拦水堰间距在30米左右为宜。分析表明,采用深槽加多道拦水堰的水力生态修复措施可以起到明显改善减水河段生境状况的作用。 相似文献
9.
Hydraulic microhabitat assessment is a category of environmental flow tools (e.g., Physical Habitat Simulation system and other methodologically similar software) that, at its core, uses habitat suitability criteria (HSC) to link values of point hydraulic variables (usually depth, velocity, and substrate/cover) to habitat values for target life stages. Although this assessment tool has been used worldwide for decades, the history of the HSC curve is relatively unknown because the foundational information is predominantly contained in obscure and often unpublished reports. We review the history of the HSC concept in applied aquatic ecology to clarify its scientific pedigree, ensure its proper use, and build a foundation for future research. We begin the review with the formative decades of the 1950's through the 1970's, when consumptive‐based western USA water law conflicted with conservation traditions and natural resource management objectives, although water allocation issues date back at least to the 19th century. By analysing the history of the HSC concept, we aim to establish the biological, hydrologic, and geomorphological conditions that must be met for the HSC concept to be successfully employed. In spite of its documented assumptions and limitations, the HSC concept will likely continue to be a useful tool to help address water resources allocation issues in defined hydrologic and geomorphic settings. We conclude that HSC‐based methodologies should be considered as one of several environmental flow approaches involved in sustainable water resources management. 相似文献
10.
在对汾河水质、入河排污量监测的基础上,选取计算模型及相关参数,以掌握汾河复流前后水环境承载能力为主要目的,以各水功能区为基本计算单元,分析计算水功能区不同来水条件下的水域纳污能力,进而提出汾河复流后各行政分区的污染物限排总量及污染物削减率。结果表明:复流后各功能区COD和NH3-N限制排污总量分别为25 139 t/a和1 158 t/a,污染物削减量分别为24 704t/a和7 857 t/a,平均削减率分别为49.6%和87.2%。若各入河排污口达标排放后,COD、NH3-N仍要削减15 936 t/a和4 356 t/a。 相似文献
11.
Predictions of habitat‐based assessment methods that are used to determine instream flow requirements for aquatic biota are uncertain, but instream flow practitioners and managers often ignore those uncertainties. Two commonly recognized uncertainties arise from (i) estimating the way in which physical habitat within a river changes with discharge and (ii) the suitability of certain types of physical habitat for organisms. We explored how these sources of uncertainty affect confidence in the results of the British Columbia Instream Flow Methodology (BCIFM), which is a commonly used transect‐based habitat assessment tool for small‐scale water diversions. We calculated the chance of different magnitudes of habitat loss resulting from water diversion using a high‐gradient reach of the North Alouette River, BC, as a case study. We found that uncertainty in habitat suitability indices for juvenile rainbow trout generally dominated uncertainty in the results of the BCIFM when large (>15) numbers of transects were used. In contrast, with small numbers of transects, variation in physical habitat among sampled transects was the major source of uncertainty in the results of the BCIFM. Presentations of results of the BCIFM in terms of probabilities of different amounts of habitat loss for a given flow can help managers prescribe instream flow requirements based on their risk tolerance for fish habitat loss. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
12.
Riverine ecosystems have been altered in many large catchments by dam development to provide water, power, flood control and navigational benefits to humans. Conservation actions in these river ecosystems are commonly focused on minimum releases of water to downstream ecosystems. Increasingly minimum release approaches are being replaced with ‘experimental’ flows that mimic natural conditions in order to benefit riverine ecosystems. While these new policies are intuitive in their design, there is limited data of how riverine ecosystems actually respond to more natural flows. A test of more natural steady‐flow water release was compared with typical fluctuating hydropower flows in the adaptive management programme at Glen Canyon Dam, Arizona, during 2008–2011 to assess growth improvements of endangered juvenile humpback chub Gila cypha. Our results are counterintuitive and show that more natural steady flows reduced growth rates of juvenile humpback chub compared with fluctuating flows when both treatments occurred within the same year. Daily growth rates during steady flows of 2009 and 2010 were 0.05 and 0.07 mm day?1 slower, respectively, than fluctuating flows those same years, despite similar water temperatures. Juvenile humpback chub also grew more slowly during steady flows that occurred in the same season. During the summer, juvenile humpback chub grew 0.12 and 0.16 mm day?1 in fluctuating flow regimes in 2009 and 2010, respectively, and only 0.07 mm day?1 in the experimental steady flow regime in 2011, despite higher water temperatures. Our results suggest that optimal conservation management policies for endangered species in regulated rivers may not always be achieved with more natural flows. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
13.
以北京市南沙河为例,从河流生态和行洪安全的角度出发,对城市河流进行探讨分析,旨在确定适宜城市发展的河流平面蜿蜒形态,为城市河流的规划发展提供理论依据。基于河流生态系统结构功能整体性概念模型,选取流速、水深作为特征性指标,以AUTOCAD散点构建南沙河老牛湾附近河段的不同平面蜿蜒形态数据,利用MIKE21模型对所构建的平面蜿蜒形态进行水动力模拟,并对其模拟结果进行梳理。根据系统分析法探讨城市河流不同平面蜿蜒形态与流速水深分布多样性、所选特征鱼类适宜生存流速水深以及河流的行洪安全要求三方面之间的关系,从而确定了蜿蜒度为1.4的平面形态对南沙河老牛湾附近河段的发展建设更为有利,明确了城市河流生态适宜性平面蜿蜒度的定义。 相似文献
14.
Elevated, more constant flows characterize the current flow regime of the Great Fish River (Eastern Cape province, South Africa) following the completion of an interbasin transfer scheme (IBT) in 1977, where prior to this the winter months were often characterized by zero flows. Changes in aquatic macroinvertebrate communities, and in particular outbreaks of the pest blackfly Simulium chutteri Lewis (Diptera: Simuliidae) have been documented in response to these altered flows. Integrated control measures of pest blackfly have been advocated based on flow reductions during the winter months. In this study, a site‐specific discharge threshold of 2 m3 s?1 was identified as a flow reduction target based on the amount of hydraulic habitat available to S. chutteri larvae within a particular rapid. Hydrological analyses showed that flow conditions have created ideal blackfly larval habitat in this rapid, with prolonged uninterupted periods (>3 months) exceeding this threshold. A model was developed to predict probabilities and severities of blackfly outbreaks, based on flow periods and water temperatures, both of which determine the success and duration respectively of the aquatic phase of S. chutteri. July was identified as the critical month for flow restriction to 2 m3 s?1 for a period of 38 days, in order to reduce the winter populations of S. chutteri in the Great Fish River at the study site and avoid the typical spring outbreaks of blackfly. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
15.
Humans have altered river flows leading to a loss of connection with floodplain habitats. The expansion of agriculture in floodplains has resulted in landscapes dominated by irrigated farmland. A key challenge in water management is to conserve existing ecological communities and habitat heterogeneity, while simultaneously maintaining engineered infrastructure for agriculture. In this study, we focused on an artificial channel network for irrigation with a regulated flow regime and its function as habitat for various fish species. Differences in hydraulic conditions among channels and compositional changes in fish species were examined to clarify functional flow heterogeneity. Analyzed using pairwise Simpson dissimilarity among sampling reaches, species turnover was positively associated with Froude number (flow intensity) differences at intermediate discharges, and with differences in cross-sectional areas (flow magnitude) at low discharges. Drastic changes in inflows should be considered for the effective conservation of flow heterogeneity, even under a regulated flow regime. Improved engineering design to manage the hydraulic environment is one option for maintaining the ecological value of lateral waterbodies in human-dominated landscapes. Our findings provide insights into the importance of functional flow heterogeneity to conserve fish species diversity. 相似文献
16.
雅砻江整江水电开发由雅砻江流域水电开发公司全权负责,因而可以做到在水电开发科学、有序、和谐的同时统筹规划采取环保措施,保护河流生态环境。针对雅砻江鱼类的分布特点、生活习性,雅砻江水电开发公司制定并实施了综合保护措施以将水电开发对鱼类资源的影响降低到最小,主要措施包括:建立鱼类自然保护区、大坝分层取水、生态流量下泄、鱼类栖息地修复、过鱼设施建设、鱼类增殖站建设等。鱼类保护设施建成运行后,为了检验鱼类保护效果,进行了实地调查分析。调查结果表明,鱼类保护设施的修建和运行取得了较好的效果。在总结鱼类保护设施建设、运行经验的基础上,提出了相关建议,以利于今后工作的改进。 相似文献
17.
European river basin authorities are responsible for the implementation of the new river basin management plans in accordance with the European Water Framework Directive. This paper presents a new methodology framework and approach to define and evaluate environmental flow regimes in the realistic complexities that exist with multiple water resource needs at a basin scale. This approach links river basin simulation models and habitat time series analysis to generate ranges of environmental flows (e‐flows), which are evaluated by using habitat, hydropower production and reliability of water supply criteria to produce best possible alternatives. With the use of these tools, the effects of the proposed e‐flows have been assessed to help in the consultation process. The possible effects analysed are impacts on water supply reliability, hydropower production and aquatic habitat. After public agreements, a heuristic optimization process was applied to maximize e‐flows and habitat indicators, while maintaining a legal level of reliability for water resource demands. The final optimal e‐flows were considered for the river basin management plans of the Duero river basin. This paper demonstrates the importance of considering quantitative hydrologic and ecological aspects of e‐flows at the basin scale in addressing complex water resource systems. This approach merges standard methods such as physical habitat simulations and time series analyses for evaluating alternatives, with recent methods to simulate and optimize water management alternatives in river networks. It can be integrated with or used to complement other frameworks for e‐flow assessments such as the In‐stream Flow Incremental Methodology and Ecological Limits of Hydrologic Alteration. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
18.
Habitat associations of upper Volga river fishes are defined within a cycle of spawning, feeding and overwintering migrations. The migration cycles of resident riverine fishes are categorized as obligate rheophils, limno-rheophils and limnophils. Forty-four fish species in 14 families occurred in the upper Volga River before regulation. Four mainstem reservoirs were constructed on the upper Volga between 1937 and 1957: Ivankovo, Uglich, Rybinsk and Gorky. They are maintained in a stage of delayed and sustained annual flood pulse. Additional impacts of reservoir construction include the creation of a new pelagic habitat, replacement of floodplains by lacustrine littoral and sublittoral habitats, creation of a complex bathyal habitat from former river channels and replacement of riverine flow patterns by pelagic water mass circulations. Populations of rheophilic species declined, while a new pelagophilic fish guild developed. Forty-six fish species are now present; seven species were lost and nine introduced after impoundment. Spawning, feeding and wintering habitats are outlined for reservoir guilds. Ichthyomass increased three to four times following reservoir construction and commercial fish harvest from Rybinsk Reservoir between 1945 and 1992 ranged from 2220 to 4304 t/y. Reservoirs of the upper Volga have limited bioproductivity due to a deficiency and uneven distribution of reproductive habitats, decreasing bottom irregularity, seasonal anomalies of flooding and draining of the littoral and sublittoral and underestimating the importance of tributaries. Lack of littoral reproductive habitat can be remedied by increasing the area of protected littoral through the construction of chains of small islands, diking and reclamation of bogged areas. Improved reproduction of migrating local stocks can be achieved by removing sand bars across tributary mouths, construction of artificial spawning grounds and restoration and preservation of preferred habitats in the main channel. 相似文献
19.
C. C. Muhlfeld L. Jones D. Kotter W. J. Miller D. Geise J. Tohtz B. Marotz 《河流研究与利用》2012,28(7):940-959
Hungry Horse Dam on the South Fork Flathead River, Montana, USA, has modified the natural flow regimen for power generation, flood risk management and flow augmentation for anadromous fish recovery in the Columbia River. Concern over the detrimental effects of dam operations on native resident fishes prompted research to quantify the impacts of alternative flow management strategies on threatened bull trout (Salvelinus confluentus) and westslope cutthroat trout (Oncorhynchus clarkii lewisi) habitats. Seasonal and life‐stage specific habitat suitability criteria were combined with a two‐dimensional hydrodynamic habitat model to assess discharge effects on usable habitats. Telemetry data used to construct seasonal habitat suitability curves revealed that subadult (fish that emigrated from natal streams to the river system) bull trout move to shallow, low‐velocity shoreline areas at night, which are most sensitive to flow fluctuations. Habitat time series analyses comparing the natural flow regimen (predam, 1929–1952) with five postdam flow management strategies (1953–2008) show that the natural flow conditions optimize the critical bull trout habitats and that the current strategy best resembles the natural flow conditions of all postdam periods. Late summer flow augmentation for anadromous fish recovery, however, produces higher discharges than predam conditions, which reduces the availability of usable habitat during this critical growing season. Our results suggest that past flow management policies that created sporadic streamflow fluctuations were likely detrimental to resident salmonids and that natural flow management strategies will likely improve the chances of protecting key ecosystem processes and help to maintain and restore threatened bull trout and westslope cutthroat trout populations in the upper Columbia River Basin. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
20.
黑河流域生态输水对下游植被变化影响研究 总被引：5，自引：1，他引：4
通过对2000—2009年的MODIS/NDVI序列分析,研究了黑河下游额济纳地区实施生态输水后该地区的植被时空变化格局。基于不同时空分辨率的遥感影像和实地考察资料,分析了形成植被变化空间差异的主要原因。研究结果表明：（1）研究区内80.4%的绿洲区植被和91.5%的荒漠区植被呈恢复趋势。绿洲区内季节累积植被指数序列趋势度大于0.14a-1的区域都存在农田开垦或弃耕地复播现象;荒漠植被的显著恢复主要发生在西河中、下游和东河下游地区。（2）研究区内19.6%的绿洲区植被和5.1%的荒漠区植被进一步退化,退化区主要分布在衬砌渠系两侧和一些干涸或径流减少的自然河流两岸,植被退化主要是乔木林的退化。（3）大范围的植被恢复主要原因在于地下水环境的整体好转,以及生态保护措施的实施;地下水环境的整体好转取决于黑河中游来水量的增加和下游输水方案的实施。（4）研究区内植被退化的直接原因在于目前输水方案实施后引起的局部地表水环境恶化。因此基于植被动态监测和局部植被对全局生态的重要性评价,确定合理的输水方案,对于区域生态环境演变进入良性循环意义重大。 相似文献
