共查询到20条相似文献，搜索用时 15 毫秒
1.
Reports concerning the influence of dams on river hydrology vary among researchers, interest groups and government agencies. These often contradicting statements may occur because changes in hydrology caused by dams are distinct for each dam and river watershed. The objective of this research was to use site specific techniques to determine if the 1967 installation of the Carlyle Dam, lower Kaskaskia River, Illinois, altered flood frequency and duration within the forested floodplain located below the dam. Results indicated a decrease in flood duration and frequency, and a decrease in annual flood frequency variation at a site 6.4 km below the dam. Pre‐dam versus post‐dam differences in flood frequency and duration at the site 32.2 km below the dam were related to climate rather than dam effects. Although dam impacts are a concern, this research shows that distance downstream from the dam and downstream tributary and watershed characteristics should be considered before assuming that the dam has changed hydrologic parameters for portions of rivers. This research also indicates that areas of the lower Kaskaskia River may still maintain hydrologic ecological integrity, and could be targeted for restoration and adaptive management purposes. Hydrologic modelling combined with river gage and on‐site well measurement techniques presented in this study could provide detailed flood frequency and duration information for land use, sociological and geomorphological questions in focus areas within river floodplains. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
2.
The effects of summer soil desiccation on plant production and plant nutrient availability (determined by wet chemical extraction) in floodplain grasslands along the rivers Allier and Loire in France were investigated. Soil desiccation in these river floodplains is the result of human interference with the natural flooding regime of rivers, such as dam construction and gravel mining. Flooding periods along the Allier have a longer duration (maximum of 202 days as opposed to 38 days for the Loire). The main comparison was between floodplain grasslands along the two rivers. Additional comparisons were made between relatively high lying, wetter areas (‘ridges’) and low lying, drier areas (‘swales’) within both floodplains. Thus, areas with different soil moisture content were examined, independent of river influences. The availability of P was higher in the Allier floodplain than in the Loire floodplain, but it was similar between ridges and swales. It was concluded that P-availability was not related to soil wetness, but to river sedimentation. Plant production, plant nutrient uptake, and biologically mediated soil processes, such as N-mineralization and nitrification, were all higher on the wetter Allier floodplain and in the wetter swales. These higher process rates were noted where higher amounts of soil bound carbon and nutrients were found as well. Plant production, N-mineralization and nitrification were moisture limited at the dry ridge on the Loire floodplain, as moisture levels were below the wilting point here (pF>4.2). On the wetter parts of the floodplain, plant production was N-limited. This was concluded from low tissue N/P ratios (about 10) and a positive relation between plant production and N-mineralization. On the wetter parts, the rate of N-mineralization depended on the size of soil organic-N pools. The size of these pools was positively related to soil wetness, which can be interpreted as a positive effect of river flooding. Reduced flooding lowers the nutrient input to floodplains and contributes to the occurrence of soil desiccation in summer, which results in lower nutrient cycling and reduced accumulation of soil organic matter. These effects have negative consequences for important floodplain functions, such as nutrient retention and biomass production. © 1998 John Wiley & Sons, Ltd. 相似文献
3.
A mesocosm study was carried out to determine whether flooding affected soil microbial structure and function. Over a 24 day period soils were either flooded or remained dry and changes in the microbial community structure, microbial metabolic activity (determined by looking at soil respiration rates and exo‐enzyme activity), community level physiological profiles and soil carbon speciation were examined. Flooding induced significant changes in the microbial community structure and increased soil respiration and enzymatic degradation rates. Shifts occurred in carbon speciation after flooding and increases in ‘labile’ carbon fractions were observed. The duration of flooding was also important for carbon dynamics and microbial community structure. Based on the results of the mesocosm experiment a conceptual model of floodplain soils response to flooding over time was formulated. The findings of this mesocosm study illustrate the importance of flooding to floodplain soil functioning. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
4.
Nikita Christopher;Astrid Vachette;Avril Horne;Anna Kosovac; 《Wiley Interdisciplinary Reviews: Water》2024,11(4):e1723
Floodplains are regularly inundated areas of land that provide ecosystem benefits for the entire catchment area, along with numerous benefits for communities making them ideal for human settlement. The management of floodplains involves an ongoing dilemma; how best to balance the need to protect urban settlements from significant flood events with the benefits that inundation brings to the environmental and cultural values of the floodplain. These flood events have been traditionally addressed using technical flood protection measures. However, nature-based solutions (NbS), provide a potential alternative approach. In this research, we analyze 29 global case studies centered on river floodplain management to investigate the barriers and enablers that affect the implementation of NbS, including floodplain restoration, mangroves, riparian forest restoration, wetland green infrastructure, among other strategies. The aim of this paper is to gain insights into improving floodplain management through the assessment of barriers and enablers evident in these case studies. The barriers and enablers were divided into six categories: social, technical, financial, political, institutional and economic and further into several sub-divided categories. Social and technical categories were the most commonly described barriers and enablers closely followed by the institutional category. The discussion is centered around four topics: understanding community and decision-maker risk perceptions, increased focus on stakeholders, managing multiple conflicting objectives, and consideration of multiple spatial scales. Further research on the uptake of NbS needs to focus on addressing risk communication and modeling, managing trade-offs, and demonstration of delayed benefits. 相似文献
5.
The Nature Conservancy and the US Fish and Wildlife Service initiated a multiyear floodplain restoration project on the Mollicy Farms tract of the Upper Ouachita National Wildlife Refuge (UONWR) located in north‐east Louisiana. Large magnitude flood pulses, remote setting and other factors presented major challenges to the monitoring effort. A planning and design process resulted in the creation of a water quality monitoring station that could deploy Yellow Springs Instruments water sampling equipment in areas with large ranges in water level throughout the UONWR floodplain. Details of the station design, fabrication and diagrams are provided. Monitoring data will help measure the impact that large‐scale floodplains have on water quality once they are reconnected to river systems. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
采用竖管法现场测定渭河漫滩饱和带渗透系数,为测定漫滩沉积物渗透系数提供一种更为简便的方法。分析渗透系数各排内的变化以及各排之间的差别。应用Matlab软件检验实验数据的统计分布规律,应用地质统计原理计算渗透系数的变异函数并分析其空间变异性。分析得出各排的渗透系数属于对数正态分布。结果表明:①78个采样点测定垂向渗透系数平均值为11.35m/d,沿河岸线方向渗透系数相近,与河岸线垂直方向渗透系数差异较大;②渭河漫滩饱和带垂向渗透系数具有较强的空间变异性。 相似文献
7.
As regards river restoration, it is fundamental to better link human pressures and environmental responses and to take into consideration not only target species or habitat but diverse ecological elements. This permits to assess sustainable restoration plan, especially concerning sediment augmentation below dams. The use of a hierarchical multicriteria approach on the Ain River permits us to assess a diagnosis of sediment deficit impact integrating several morphological (channel shifting, river bed degradation and river bed coarsening) and ecological components (Riparian and floodplain lake and fish communities). Our diagnosis also integrates a temporal and spatial approach better to link human pressures and environmental responses and to identify the dam effects amongst other drivers (e.g. grazing decline and channel regulation). The results confirm causality links between sediment deficit and slight channel bed degradation (0.01 m.year?1) or channel bed paving and thus highlight the impact of the dam on the drying of the riparian forest and on former channel community. However, the relationship between incision and reduction in active channel lateral mobility is more difficult to establish. The role of sediment deficit in the current variability of the riparian regeneration capacity and, thereby, landscape diversity along the lower valley remains unclear. This study also confirms the relevance of using different ecological indicators, notably because all components present different adjustment time scales, whereas some of them are more sensitive to other impacts. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
8.
J. N. Callow 《河流研究与利用》2012,28(8):1072-1092
The approaches used to manage rivers have been developed and adapted to many different problems and settings. Because of their relatively low cost, vegetation‐based approaches implemented at the reach, landholder and catchment scales have become the foundation for river management in most landscapes. In many dryland agricultural catchments, secondary (anthropogenic) salinity caused by clearing native vegetation has resulted in rising saline groundwater, streamflow salinity values that exceed seawater and severe the degradation of riparian vegetation communities. The potential effectiveness of vegetation‐based strategies in these landscapes remains largely unknown, yet these strategies are still widely pursued. This study initially investigated the patterns of vegetation recovery and recolonization following a large flood in a saline river that disturbed the system. A conceptual model was developed to describe spatial patterns of where different vegetation types had regrown and recovered in relation to controls exerted by streamflow salinity, surface texture characteristics, topography and reach morphology. Using this model, vegetation‐based river management options for different reaches were developed, and their potential effectiveness in stabilizing reaches was investigated using a 1‐D hydraulic modelling approach. This study finds that in a dryland catchment with high stream salinity (20 000–93 000 mg L?1), there is still a strong potential for successful vegetation‐based management, but only in selected reaches. Results showed that changes in stream power and channel velocity were not associated with the areas of most severe vegetation degradation. Rather, there is a complex interplay between channel morphology, channel slope and places of potential vegetation growth within a reach. This paper outlines an approach to evaluate the potential success of vegetation‐based river management in saline landscapes. It identifies the need to prioritize investment based on the following: an understanding of factors controlling revegetation potential, the likely impact of revegetation in mitigating adverse channel changes and the proximity of reaches to high‐value infrastructure and biodiversity assets. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
9.
The sediment and nutrient budget in the floodplain reach of the River Adour in southwest France has been examined over a 1‐year period (1991–1992). Outputs of total suspended matter, dissolved inorganic nitrogen (i.e. nitrate+ammonium ions) and dissolved inorganic phosphorus (DIP) and particulate phosphorus (PP) have been compared with inputs. Alternating phases of mobilization and retention are observed for all the elements considered. Low water periods in summer allowed retention of both soluble material (24–26% for inorganic nitrogen) and suspended matter (9–19%). However, mobilization of PP associated with suspended matter transport during these periods. Elevated discharges associated with increased rainfall during the autumn period induced significant mobilization for all elements. In contrast, the winter flood event gave rise to a retention of particulate material (i.e. suspended matter and PP, 11% and 26%, respectively), but a loss of soluble materials (5% for inorganic nitrogen and 186% for DIP). The spring flood event produced retention for particulate materials (26%) while inducing losses of inorganic nitrogen (9%) and gains of DIP (7.4%). These results are related to riparian vegetation and the dynamics of nutrient cycling within the floodplain. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
10.
This study evaluated the influence of the flood regime of the Cuiabá River on the reproductive dynamics of fish species with different reproductive strategies. Sampling was carried out at ten sites in the basin, between March 2000 and April 2004. The reproductive strategies evaluated were long‐distance migrant (LM), short‐distance migrant (SM), sedentary with parental care (PC) and sedentary or SM with internal fertilization (IF). Period, duration and intensity of floods were the flooding attributes considered. Duration and time of spawning were evaluated using the index of reproductive activity (IRA), and inferences concerning reproductive allocation were based on the analysis of gonad weight. Reproductive success was evaluated based on the annual catch of young‐of‐the‐year of each species. Reproductive dynamics and flood regime were closely correlated; the reproductive peaks of fishes using all four strategies always preceded flood peaks. Intense floods favoured gonadal development of LM and PC, but were less important for IF. In relation to juvenile survival, the occurrence of floods appeared to be crucial for the strategies of LM, PC and IF, because such floods increased fish survival in the period of initial development. In contrast, SM appeared to be less dependent on floods for reproduction. These results indicate that, except for SM, floods have an important role in the recruitment of species using other reproductive strategies, and influence spawning success as well as juvenile survival. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
11.
为研究汉口江滩芦苇生长过程与淹没水深和淹没历时的关系,考虑淹没水深和淹没历时对芦苇生长带来的胁迫作用,对现有芦苇生长动态物候模型进行改进,并利用改进后的模型模拟了汉口江滩芦苇在不同淹水胁迫条件下的生长过程。结果表明：汛期汉口江滩芦苇地上生物量因淹水胁迫而急剧减小,淹水胁迫效应不可忽视,且汛期水量越大、持续淹没时间越长,淹水胁迫导致的芦苇地上生物量减小速度越快;淹水胁迫导致汉口江滩芦苇地上生物量的减少值与淹没历时和水深大于2 m的淹没历时之间存在较好的幂函数关系,且水深超过芦苇适宜淹没阈值带来的淹水胁迫作用占主导地位。 相似文献
12.
Highly productive floodplain rivers in Brazil and elsewhere provide livelihood and recreational fishing for millions of people around the world, but damming and controlled water discharge are a threat to these valuable ecosystems. Supplemental water releases (SWRs) at a dam are increasingly used for restoring fisheries productivity in many floodplain rivers. We proposed a conceptual model for a hypothetical water release to enhance fisheries using Três Marias Reservoir (TMR) on the São Francisco River (SFR), Brazil. The information needed by the model follows: (i) Biologically, what is the best release date? (ii) How much water will be released? (iii) What is the pattern of impoundment and how much impounded water will be released? (iv) What is the lost revenue to the power plant associated with SWR? (v) What is the relationship between river discharge and the area of floodplain that is flooded? (vi) What is the relationship between SWR and fisheries value? Ichthyoplankton studies in the SFR showed a clear positive relationship between fish density and water level (WL). While the relationship between WL and floodplain area flooded and recruitment is not known, we concluded the best date for release is when there is a natural flood, which naturally triggers fish spawning and the SWR will add to the natural flood and cover a greater floodplain area. The released volume will range from 0.302 km3 to 2.192 km3, depending on SWR duration. In most years from 1976 to 2003, TMR impounded enough water for SWR only in the second half of the fish‐spawning season (January–March). Lost revenue at TMR depended on release volume and ranged from US$ 0.493 million to US$ 3.452 million for the actual power rate. However, SWR could increase commercial fisheries income an estimated US$ 4.468 million. We forecast that SWR can bring fisheries benefits that surpass the lost revenue. Published in 2007 by John Wiley & Sons, Ltd. 相似文献
13.
14.
The St. John's Bayou water control structure near New Madrid, MO, connects the main Mississippi River to two large backwater areas called the New Madrid Floodway and St. John's Bayou. While this area has been altered, the New Madrid Floodway and St. John's Bayou account for the only substantial portion of the historic Mississippi River floodplain that remains and provides the only critical connection between backwater/floodplain habitat and the river. Fish passage was evaluated during April–December 2010 using ultrasonic telemetry. Stationary receivers were placed strategically at five locations above and below the structure in St. John's Bayou, in the floodway and the outlet to the Mississippi River. A total of 100 individuals representing 14 species were tagged. Total number of detections during an 8‐month period was 1 264 717. Fifteen individuals representing five species moved into the Mississippi and Ohio rivers; seven individuals returned to St. John's Bayou. Thirteen of the 14 species moved upstream through the structure. Of the 85 individuals that stayed in the bayou, 29 fish passed through the structure for a total of 92 passage events. The downstream : upstream passage was roughly 50:50. Passage was correlated with river rise, with frequency of passage being higher in spring, but passage occurred each month during the study. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
15.
Two data sources, field‐collected samples and values in the NRCS SSURGO database, were used to estimate organic carbon concentration (%) and stock (Mg C/ha) in floodplain soils along rivers of the tallgrass and shortgrass prairie within the United States. Field sampling of 6 sites in the tallgrass prairie and 6 sites in the shortgrass prairie (total sample size of 370 vertical cores) indicates that percent organic carbon within a planar cross section through floodplain sediment at a site is spatially heterogeneous and does not decline systematically with depth, but statistical analyses indicate that soil organic carbon is randomly distributed. The median values of organic carbon concentration at both field‐sampled and sites remotely sampled based on soil maps in the tallgrass prairie are significantly higher than those of the shortgrass prairie. Median values of organic carbon stock are not significantly different between those obtained from forested sites for comparison and either shortgrass or tallgrass prairie sites but are significantly higher at tallgrass than at shortgrass prairie sites. These results are surprising because upland net primary productivity in prairies is lower than in forested sites. We infer that the historical abundance of floodplain wetlands in river corridors of the tallgrass prairie results in high organic carbon stocks in tallgrass prairie river corridors. This implies that management designed to enhance carbon sequestration should focus on floodplain soils, especially in the tallgrass prairie region, as well as on upland forests. 相似文献
16.
River restoration is widely applied, although its effects are poorly understood, and degraded habitats might be difficult to improve. Moreover, there is a lack of monitoring as well as few systematic comparisons of restoration methods. This study presents results of a 4‐year monitoring on River Inn (southern Germany) investigating restoration by gravel or sand addition or embankment removal. The results were compared with reference sites that represent the pre‐restoration conditions. At the landscape scale, we analysed vegetation types based on aerial photographs, whereas at a smaller scale, we undertook vegetation surveys and evaluated species composition, growth, and life form, as well as the proportion of the target vegetation. After 4 years, the data indicated a “negative resilience” of the vegetation back to the state prior to restoration. The structural analysis revealed an extensive spread of reed at expense of bare soil. Thus, the species composition largely regressed to the pre‐restoration conditions, and neither annuals nor other pioneer species showed a long‐term benefit of river restoration. There were differences among the three restoration treatments after 2 years, but no longer after 4 years. However, the river restoration had three positive outcomes: (a) There was a temporary benefit for pioneer vegetation that most likely replenished the seed bank of the respective species, (b) the valuable reed communities showed resilience, and (c) the measures allowed some practical learning as expected for adaptive restoration. 相似文献
17.
Thomas C. Wagner;Romy Woellner;Veronika Kloska;Johannes Kollmann; 《河流研究与利用》2024,40(6):1125-1141
Channel migration, furcation, and vegetation succession are characteristic processes of braided gravel rivers in Alpine regions. These are associated with a frequent turnover of large parts of the active floodplain. However, more than one century of river regulation has reduced or destroyed most of these ecosystem dynamics. More recently, there have been attempts to restore at least some sections of degraded rivers, while there is little monitoring of the biogeomorphological dynamics of such rivers. Thus, we did a four-year analysis of four representative sections of the upper River Isar in Southern Germany differing in their degree of naturalness. Dynamics of channels, gravel bars, and vegetation were recorded by drone images, and braiding and gravel indices were calculated. When comparing the near-natural, semi-natural, degraded or restored sections, there was a gradient of decreasing channel migration, gravel bank expansion, and bank erosion due to a reduced turnover frequency. Biogeomorphological variation among years correlated with log peak discharge within the four sections. In addition, the cover and height growth of vegetation increased with river degradation, and channel migration was positively related to the braiding index. The total turnover of the active river corridor and of the vegetation were positively correlated with log peak discharge within the four sections. The floodplain dynamics of the restored section were improved compared to the degraded section but did not reach a near-natural state. Thus, Alpine river sections with contrasting degrees of naturalness differ in terms of habitat turnover and vegetation succession, and these characteristics can only partially be restored by local measures. 相似文献
18.
Abstract A fundamental conflict occurs when a floodplain, fluvio-morphologically formed by the river for draining its high flows, is occupied and developed by humanity. Consequently, damages are experienced that are the inevitable costs of occupancy of the floodplain. A systematic methodology is suggested for formulating an optimal scheme for addressing any flood situation with its own unique characteristics. This methodology embraces all available measures, structural and non-structural, traditional and modern, in evolving the best scheme. Diverse flood situations in New Brunswick (Canada), the Nile River Basin and Bangladesh exemplify three flooding situations radically different in origin and character. Finally, some important conclusions are drawn and recommendations are made for approaching solutions to major flood problems 相似文献
19.
许多城市对市区内的河道进行综合开发整治,以美化城市环境,为市民提供休闲娱乐场所。综合开发涉及许多方面,从水利的角度对市区河道开发治理提出要求,强调河道治理开发应确保河道行洪安全,景观建设在布置及结构形式上应注意对堤防安全的影响,保护好水资源,协调好上下游用水关系等。 相似文献
20.
本文根据实测资料说明了宽河段的滞洪效果和稳定的河道主槽对控制河势的重要作用。由于黄河下游洪水峰高量小,宽河段的槽蓄能力有利于滞洪,而且由于宽河段的滩区落淤沉沙作用,也有利于减缓河床的抬升速度。据此,作者提出“宽河定槽”的治河防洪原则。它是传统的“宽河固堤”治河策略的一个发展,也是近五十年治黄经验的总结。 相似文献