共查询到20条相似文献，搜索用时 15 毫秒
1.
Worldwide large rivers have been severely modified by human intervention. Many modifications result in disconnection of the river from floodplain and off‐channel habitats generally characterized by lower velocities and Copyright © 2016 John Wiley & Sons, Ltd. shallower depths relative to the main channel, conditions vital to many organisms. Extensive levees on the Middle Mississippi River (MMR) have cut off backwater systems and disconnected the river from 80% of its floodplain. However, the system is characterized by large side channels associated with islands. We examined a long term data set for differences in physical (e.g. depth and velocity) and water quality metrics (e.g. temperature, suspended solids, dissolved oxygen, chlorophyll, % organic matter) between the main and side channels of a 128‐km reach of the MMR. We compared variability between main and side channels using the coefficient of variation (COV). All metrics differed between habitats. Side channels were shallower with lower velocities and had greater mean and COV of % organic matter and more variable dissolved oxygen concentrations. Velocity, temperature, and suspended solids were similar in the spring. COVs were lowest in both habitats during the spring for all metrics except temperature and DO. Resource management in the MMR tends to focus on maintaining existing side channels because of the difficulty of working in the heavily used navigation channel. This study shows that these actions protect areas that function differently than the main channel for most of the year. However, our results also highlight the need for restoration activities aimed at restoring floodplain connectivity, especially during the spring. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
2.
丁坝在三屯河河道整治中的成功经验 总被引：1，自引：0，他引：1
三屯河渠首以下3km范围内的河道，东西两岸毗邻三屯河东西干渠及耕地，河道两岸多年遭受洪水的严重侵蚀破坏，直接危及到了下游东、西引水干渠的安全。2000年，对该段河道采用丁坝型式进行了总体整治设计，当年秋季竣工。经过近3a的运行，整治效果较明显，彻底根治了水患，确保了东、西引水干渠的安全，取得了巨大的防洪效益。 相似文献
3.
Even in heavily impounded river ecosystems, aquatic populations and communities retain limited connectivity via movement through dams. This connectivity has the potential to influence population dynamics but has been infrequently characterized. We used 1995–2008 paddlefish mark–recapture data to perform the following: (i) quantify rates of movement through dams and (ii) examine the influence of dam discharge on fish passing dams. We found that there are substantial one‐way (upstream to downstream) population connections maintained via fish passing dams and that dam discharge is a key driver of downstream fish movement. Results of our study suggest that population connections maintained by fish passing dams can play an important role in population dynamics depleting upstream populations and subsidizing downstream populations, particularly in years with high flow events. We suggest that the influence of hydrology on maintaining populations in fragmented ecosystems is an increasingly important consideration for conservation and management of aquatic ecosystems in the face of predicted hydrological changes from climate change. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
4.
R. Pepijn van Denderen Ralph M. J. Schielen Menno W. Straatsma Maarten G. Kleinhans Suzanne J. M. H. Hulscher 《河流研究与利用》2019,35(9):1597-1603
Side channels are commonly constructed to reduce the flood risk or to increase the ecological value of a river. Such artificial side channels generally aggrade. We categorize the development of side channels based on the sediment that is deposited in these channels. Based on this categorization, we determine the main mechanisms that affect their development, and we propose an initial framework on how to predict the long‐term development of side channels. The results can be used to design, operate, and maintain side channel systems. 相似文献
5.
John M. Nestler Charles H. Theiling Kenneth S. Lubinski David L. Smith 《河流研究与利用》2010,26(10):1199-1219
Ecosystem restoration planning requires quantitative rigor to evaluate alternatives, define end states, report progress and perform environmental benefits analysis (EBA). Unfortunately, existing planning frameworks are, at best, semi‐quantitative. In this paper, we: (1) describe a quantitative restoration planning approach based on a comprehensive, but simple mathematical framework that can be used to effectively apply knowledge and evaluate alternatives, (2) use the approach to derive a simple but precisely defined lexicon based on the reference condition concept and allied terms and (3) illustrate the approach with an example from the Upper Mississippi River System (UMRS) using hydrologic indicators. The approach supports the development of a scaleable restoration strategy that, in theory, can be expanded to ecosystem characteristics such as hydraulics, geomorphology, habitat and biodiversity. We identify three reference condition types, best achievable condition (A BAC), measured magnitude (MMi which can be determined at one or many times and places) and desired future condition (ADFC) that, when used with the mathematical framework, provide a complete system of accounts useful for goal‐oriented system‐level management and restoration. Published in 2010 by John Wiley & Sons, Ltd. 相似文献
6.
The planimetric shifts in channel location of large alluvial rivers are a critical component in the creation of diverse structures and functions in riverine habitats. Engineered management schemes must also compensate for this type of channel change to protect resources and maintain navigation channels. The stability of the Lower Mississippi River channel was assessed through an analysis of historical records of channel position produced and archived by the United States Army Corps of Engineers. Channel location was recorded for the years 1765, 1820, 1881, 1915, 1930, 1937, 1960 and 1970. Channel stability was measured by two introduced metrics on a cell‐by‐cell basis: (1) the standard deviation of Euclidean distance to a channel cell for the entire period of record, and (2) the rate of Euclidean distance change between years in the period of record. At a coarse spatial scale, channel instability increased in the downstream direction. The variability of channel stability also increased in the downstream direction. Analysis of this variability identified alternating areas of high and low stability occurring with greater frequency as distance downstream increased. These findings are validated by past studies of channel stability along the Lower Mississippi River. As a result, the proposed metrics provide a consistent, quantitative, efficient and cost‐effective means of identifying areas of channel instability at several spatial scales. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
7.
Wing dikes and other anthropogenic modifications have heavily altered riverine ecosystems. Recent efforts to reach a compromise between the needs of the river transportation industry and natural resource conservation include dike modification. Dike notching permits water flow through the landward portion of the dike and has been purported to provide suitable habitat for fish and other river biota while maintaining the navigation channel. L‐head dikes are flow‐control structures that create calm backwater‐like habitats downstream. However, few researchers have examined the actual effects of dike notching on water quality or fish communities. We compared standardized catch per unit effort and overall community structure for 50 fish species among un‐notched dikes, notched dikes and L‐head dikes in the Middle Mississippi River, sampled as part of the US Geological Survey's Long‐Term Resource Monitoring Program. There were no differences in standardized catch per unit effort for 64% of the fishes examined. Five species known to be associated with lotic habitats were most abundant near L‐head dikes. Seven species were more abundant at un‐notched dikes than notched dikes, while six species were more abundant at notched dikes than un‐notched dikes. Non‐metric multidimensional scaling suggested differences in overall fish community structure between un‐notched and other dike types. Detailed physical habitat studies should be conducted to better understand the effects of dike modification. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
8.
The Missouri River has been extensively altered as the result of channelization, bank stabilization, and the construction of six main stem reservoirs. In response to the resultant habitat loss, the US Army Corps of Engineers was tasked with restoring approximately 8100 ha of shallow water habitat (SWH), in part, for the benefit of the endangered pallid sturgeon (Scaphirhynchus albus). Construction of off‐channel habitats involves the removal and disposal of excavated alluvium either by direct discharge into the river or by secondary erosion, which raised concerns regarding the introduction of sediment and associated nutrients into the Missouri River. Soils from nine side‐channel chutes were sampled to represent nutrient concentrations from habitat restoration activities. Soils from 12 historically undisturbed sites were also sampled to represent reference conditions in the Missouri River flood plain. The results of this study indicate that nutrient characteristics of soils from selected SWH locations generally are similar to those of historically undisturbed soils. The estimated mass of total phosphorus from chutes accounted for 1.9% of Missouri River and 0.5% of Mississippi River total phosphorus loads during the 1993–2012 analysis period. The mass of nitrate, the constituent most closely related to gulf hypoxia, was 0.01% or less of the Missouri and Mississippi River nitrate loads. Sediment volumes from the chutes accounted for 3.1 and 1.5% of total suspended loads from the Missouri and Mississippi Rivers. Overall, the introduced sediment from side‐channel chute construction associated with SWH restoration accounts for a small portion of total nutrient and sediment transport in the Missouri and Mississippi Rivers. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. River Research and Applications published by John Wiley & Sons, Ltd. 相似文献
9.
The Upper Mississippi River is maintained in its current navigable state through impoundments, dredging, and other engineering projects. These stressors, along with anthropogenic impacts and natural system processes, led to declines in aquatic vegetation and the loss of fish and wildlife habitat, with a major downturn the late 1980s and early 1990s. Large‐scale restoration projects, such as the one evaluated here, are primarily designed to rehabilitate and enhance fish and wildlife habitat. We determined whether an individual restoration project, construction of an island complex, fulfilled a programmatic goal of re‐establishing diverse and abundant native aquatic vegetation. Eighteen years of aquatic vegetation monitoring data from impact and reference areas were compared to evaluate the anticipated direct effects (within 400 m of the constructed islands) and indirect effects (>400 m downstream of constructed islands) of restoration. Impact areas were also compared with an unrestored negative reference area ~200 km downstream of the project and with a positive reference area in adjacent, relatively natural backwaters. Only indirect effects of restoration were evident. Prevalence and species richness of aquatic vegetation in both of the impact areas and in the negative reference area increased prior to restoration, suggesting large‐scale improvement independent of the project examined here. Indirect effects were demonstrated as further increases in both prevalence and species richness coinciding with restoration in the area >400 m downstream of the restoration. We conclude that increased abundance and diversity of aquatic vegetation was partially achieved, with observed improvements potentially linked to reduced wind fetch. 相似文献
10.
Habitat management is a crucial aspect of fisheries management. Without knowledge of habitat associations, fisheries scientists are unable to effectively make habitat conservation or restoration recommendations. This becomes especially prominent when trying to manage commercially harvested populations and protect threatened or endangered species. To determine juvenile fishes habitat associations in the Middle Mississippi River, we analysed mini‐trawl catch data of six common juvenile fish species: blue catfish (Ictalurus furcatus), channel catfish (Ictalurus punctatus), channel shiner (Notropis wickliffi), freshwater drum (Aplodinotus grunniens), paddlefish (Polyodon spathula), and shovelnose sturgeon (Scaphirhynchus platorynchus). Overall, we conducted 2251 mini‐trawl sampling efforts between 2002 and 2013, resulting in the capture of 23,742 target specimens. Catch per unit effort was evaluated by structural habitat (i.e. velocity, depth, and substrate). Overall, these data suggest that juvenile fish species are more prevalent in shallow water and slower velocities. Ultimately the information garnered during this evaluation should be incorporated when considering habitat modifications, especially those modifications that impact the availability of shallow‐low velocity habitats. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
11.
Charles H. Theiling 《河流研究与利用》1995,11(2):227-238
Upper Mississippi River ecological integrity has been severely compromised by human activity during the last 50 years. In response to the continuing decline of natural resource values, two approaches for protecting and improving the Upper Mississippi River-floodplain ecosystem have been used. Habitat rehabilitation and enhancement projects are being constructed at 54 locations to provide site-specific rehabilitation. The projects are designed to counteract the adverse ecological effects of sedimentation through (1) flow introductions, (2) the isolation of backwaters; and (3) flow diversions and wave breaks. Channel maintenance projects are being re-evaluated in an attempt to construct or modify existing river training structures that are environmentally sympathetic. The latter approach works with the river's energy, whereas the former attempts to overcome riverine processes. Both approaches have significant limitations because they affect limited areas. A proposal is presented that restores some ecosystem integrity by re-establishing occasional low river stages that occurred before the implementation of the Upper Mississippi River Navigation System. 相似文献
12.
13.
黄河下游丁坝缩窄河道泥沙冲淤特性试验研究 总被引：1，自引：0，他引：1
通过动床模型试验研究了黄河下游裴峪至官庄峪丁坝缩窄河段,在河道不同位置布设丁坝,不同情况下丁坝相对长度(丁坝长度与原河道宽度之比值)对河道泥沙冲淤变化的影响。结果表明：水沙运动要素变化受丁坝布设位置和长度等影响较大,随着丁坝相对长度的增加,汛期主河槽冲刷量和滩地淤积量逐渐增大,主槽范围相应扩大,其高程普遍呈下降趋势,特别是缩窄断面导流堤顶端部位出现明显的局部冲刷坑,束水冲沙、增大输沙能力的效果明显。当丁坝相对长度大于0.50时,主流线偏移、断面流速分布和河床冲淤的变化速率明显增大,不利于河道稳定。 相似文献
14.
下荆江裁弯对荆江洞庭湖影响分析 总被引：12，自引：5，他引：7
下荆江中洲子、上车湾河湾实施裁变工程,沙滩子河湾发生自然裁弯,迄今已有２０余年。裁弯后,荆江分流入洞庭湖的水量、沙星锐减、加速了江湖关系变化。根据原型实测资料,对裁弯后荆江河道和江湖关系演变、工程效益和对江湖防洪的不利影响进行分析,指出１９８０年后,荆江河床已处于部淤平衡状态;洞庭湖口洪道和城陵矶－武汉河段泥沙淤２积问题对防洪影响较小,并对三峡工程运用后,进一步贯彻“江湖两利”方针,提出建议。 相似文献
15.
16.
The influence of naturally occurring in‐channel large wood (LW) on the hydraulics, hydrology and geomorphology of rivers is well documented. To inform management and better understand naturally occurring or artificially placed LW, hydraulic and hydrological models are applied to predict the possible benefits and drawbacks for habitat, sediment management and flood risk mitigation. However, knowledge and guidance on appropriate representation in models, needed to underpin realistic predictions, is lacking. This could lead to unrealistic expectations of the effectiveness of LW for different river management goals. To date, seven types of LW representation in hydraulic and hydrological models have been applied, the range partly reflecting the variety of LW, model types, scales and purposes. The most common approach is by altering channel roughness to represent flow resistance. Although qualitatively the effects of LW have been captured using models, to date quantitative validation, as well as transferable knowledge to help a priori parameterization of LW representations, remain limited. Therefore, additional empirical investigations and robust model validation are required to inform defensible LW representations for specific purposes and scales in numerical models coupled with better accounting of input uncertainty to improve confidence in predictions. Future studies should also consider a greater range of artificial and natural LW features, settings, larger spatial scales and better account for temporal variability of flow, morphology and LW configuration. This article is categorized under:
- Water and Life > Methods
- Science of Water > Methods
- Water and Life > Nature of Freshwater Ecosystems
17.
本文从水流泥沙运动方程出发，通过附加河流边界条件的方法，分析了河相关系井给出了顺直型、弯曲型及分汊型河流形成的必要条件，但由于很多影响河相关系和河型形成的其它因素没有考虑，因此本文只是对实际情况的简化分析。 相似文献
18.
左东启 《水利水电科技进展》2001,21(4):2-13
在学习、整理有关黄河形成发育过程和黄河下游大改道变迁分期研究成果的基础上 ,结合当前黄河治理中的重大问题 ,对黄河决溢、改道的变化进行了分析归类 .按照黄河下游河道演变的成因、影响及其与相邻河系的关系等 ,将黄河发育进化分成 9个历史阶段 .把黄河改道纳入黄淮海平原发育的整体格局的演变中综合全面研究 ,以弥补只视改道为各个孤立、偶发事件的研究方法局限 .由此认为 ,2 0世纪后期是黄河和黄淮海平原完全发育成熟的阶段 ,而 2 1世纪开始了黄河的新纪元 .在此转折点时期提出供考虑研究的若干治河意见方案 相似文献
19.
Artificial structures have been used to potentially increase fish production by providing cover, feeding and spawning areas. In some rivers, the United States Army Corps of Engineers has constructed dikes to provide additional habitat for river fishes and to mitigate for navigation impacts to young fishes. This study was designed to test whether such structures function as viable habitats as evidenced by increased abundances relative to reference areas lacking artificial dike structures. Dikes and reference sites in the Kanawha River, West Virginia were sampled 21 times between July 2002 and October 2003. We found a difference in taxonomic composition among fish using dikes relative to reference areas. Artificial dike structure use was most important among Centrarchidae species, especially juveniles, including black bass and several species of Lepomis. Further, distribution of fish between areas with and without dikes appears most affected by water temperature in 2002 and by short‐term river flow in 2003. These patterns suggest these artificial structures are viable mitigation measures that target and benefit fish of economic interest. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
20.
Ted. R. Angradi Debra L. Taylor Terri M. Jicha David W. Bolgrien Mark S. Pearson Brian H. Hill 《河流研究与利用》2010,26(3):261-278
Woody debris has several important roles in running water. Less is known about the ecology of wood in great rivers than in smaller rivers and streams. We used a probability survey to estimate the abundance of littoral and shoreline wood along the following mid‐continent great rivers of the United States in summer 2004–2006: the Missouri River, Upper Mississippi River, and the Ohio River. We counted wood pieces >0.3 m in diameter from a zone between the bank full level out into the river 10 m. We categorized wood according to its origin and function as “beached” (transported from upriver but not providing aquatic habitat), “wet” (origin unknown and providing aquatic habitat; includes snags), or “anchored” (attached to the bank at its current location and providing aquatic habitat). We counted 5900 pieces of wood at 447 sites across rivers. Approximately 56 percent of pieces were beached, 30 percent were wet, and 14 percent were anchored. Overall, mean abundance of wood was 2.6 pieces of wood 100 m?1 of shoreline (approximately 3.0 m3 100 m?1). Abundance of wood (pieces per unit distance of river) was much lower than has been reported for many smaller streams and rivers. There was more wood along the Upper Mississippi River (3.3 pieces 100 m?1) than elsewhere (≤2.4 pieces 100 m?1). The mean abundance of wood on the Ohio River decreased significantly between the 2004 and 2005 survey periods due to high flows. Longitudinal patterns in wood abundance were weak. There was less anchored and wet wood along shorelines protected by revetment (e.g., rip rap). There was generally more wood along shorelines where the riparian land use was characterized as forest rather than agriculture or developed. Mean abundance of wood along forested, un‐revetted shorelines was approximately four pieces 100 m?1 of shoreline (= 80 pieces km?1 of river). This estimate of mean wood abundance for what amounts to least disturbed riparian and shoreline conditions is relevant for great river bioassessment and management. Published in 2009 John Wiley & Sons, Ltd. 相似文献