洪水脉冲的生态效应

在阐述洪水脉冲概念的基础上，指出洪水脉冲是河流-滩区系统诸如生产、分解和消费等基本生态过程的主要驱动力。随后分析了洪水脉冲生态学机理。并在讨论洪水脉冲概念中考虑了河流水文情势的重要性，研究了洪水脉冲对河流-洪泛滩区的生物过程的影响，讨论了洪水脉冲概念对河流生态修复的指导意义，提出了基于自然水文情势改进水库调度的原则，指出河流-洪泛滩区系统不可分割的整体性，恢复河流与滩区、湖泊和湿地的连通性是实现洪水脉冲的必要条件。     

POST‐DAMMING FLOW REGIME DEVELOPMENT IN A LARGE LOWLAND RIVER (VOLGA,RUSSIAN FEDERATION): IMPLICATIONS FOR FLOODPLAIN INUNDATION AND FISHERIES

Periodic flooding plays a key role in the ecology of floodplain rivers. Damming of such rivers can disturb flooding patterns and have a negative impact on commercial fish yield. The Volga River, the largest river in Europe, has a regulated flow regime after completion of a cascade of dams. Here, we study effects of damming on long‐term discharge variability and flood pulse characteristics. In addition, we evaluate the effects of the altered flood pulse on floodplain ecosystem functioning and commercial fish yields. Our results indicate that both flood pulse and fish populations of the Volga–Akhtuba floodplain have varied considerably over the past decades. After damming, annual maximum peak discharges have decreased, minimum discharges increased, but average discharges remained similar to pre‐damming conditions. Moreover, because of bed level incision of over 1.5 m, a higher discharge is needed to reach bankfull level and inundate the floodplains. Despite this significantly altered hydrological regime and subsequent morphological changes, current discharge management still provides significant spring flooding. However, commercial fish catches did decrease after damming, both in the main channel and in the floodplain lakes. All catches were dominated by species with a eurytopic flow preference, although catches from the main channel contained more rheophilic species, and floodplain catches contained more limnophilic and phytophilic species. The strong increase of opportunistic gibel carp (Carassius gibelio) around 1985 was apparent in the main channel and the floodplain lakes. Despite the hydrological changes, the decrease in overall catches, and the upsurge of gibel, we found a strong positive effect of flood magnitude in the previous year on commercial fish yield in the floodplain lakes. This suggests that under the current discharge management there still is an increased fish growth and/or survival during high floods and that functioning of the floodplain is at least partly intact. Copyright © 2011 John Wiley & Sons, Ltd.     

黄河水量统一调度与调水调沙对河口的生态水文影响

从具有生态学意义的流量、频率、出现时间、持续时间和变化率等5种水文要素出发，采用水文变化指标体系定量评估了黄河水量统一调度与调水调沙对河口段生态水文情势的影响，讨论了河口环境水流需求以及调水调沙后水文情势对环境水流的满足程度。研究结果表明，与水量统一调度前相比，水量统一调度与调水调沙后利津断面水文情势有所改善，年极小值流量明显增加，但是水文过程变化率降低，洪水漫滩过程消失，水文过程趋于平缓。目前河口段水文情势能够满足枯水期适宜生态流量需求，汛前4—5月关键期无法满足适宜生态流量与流量脉冲过程，汛期除缺乏洪水脉冲过程外，基本能够满足高流量输沙需求。     

耦合水文情势及鱼类需求的生态调度研究

针对丰满水库下游鱼类多样性减少的问题,在满足最小生态流量需求的基础上,开展了营造适宜鱼类的水文情势研究。通过筛选改变度大且适宜鱼类的水文情势指标构建生态完整度函数,将此作为生态目标建立水库多目标优化调度模型。调度结果表明,所建立的生态调度模型在满足发电、供水和最小生态需水量的基础上,可将生态完整度至少提高48%,其中,涨水率、高流量脉冲数指标隶属度分别增加了0.112、0.261,且涨水率指标在枯水年改善程度好,高流量脉冲数指标在枯水年改善程度大、丰水年改善程度小。本文所建立的模型显著提高了适宜鱼类水文情势的生态完整度,可为有鱼类修复任务的流域提供参考。     

Examining the ecological consequences of restoring flow intermittency to artificially perennial lowland streams: Patterns and predictions from the Broken—Boosey creek system in northern Victoria,Australia

The reinstatement of natural flow regimes is a rapidly emerging issue in river restoration worldwide. In northern Victoria, Australia, efforts are presently underway to restore a natural, intermittent flow regime to several streams which have received perennial diversions for both irrigation and stock and domestic water‐supplies for over 100 years. A pipeline to deliver water to landholders will significantly reduce transmission losses throughout the system allowing irrigation canals and diversion weirs to be decommissioned. The motivation for flow alteration in this system lies primarily in reducing inefficiencies in water delivery which, in turn, will be used to meet escalating demands on water resources. The ecological impact of the flow regime shift on these streams is likely to be substantial. This study utilized an existing artificial hydrological gradient (from perennial to intermittent) in two creek systems, to explore relationships between flow regime and a range of ecological variables. These data provide a benchmark against which to assess ecological changes once flow has been altered and form the basis for predicting changes that can assist future management decisions. Data collected from 10 sites across a strong hydrological gradient detected clear differences in geomorphology, water quality and biotic assemblages (macrophytes, macroinvertebrates and fish). By examining the relationship between flow regime and the distribution of biota we identify both the positive and negative outcomes of restoring naturally intermittent flow regimes within artificially perennial lowland streams. The reinstatement of intermittent flow regimes in artificially perennial streams will continue in many parts of the world as water delivery via these systems becomes increasingly uneconomical. While flow restoration may in principle be regarded as a positive step, these findings emphasize the need to consider fully the ecological consequences of restoring historical hydrological regimes to streams within the context of other human induced catchment disturbances. Copyright © 2009 John Wiley & Sons, Ltd.     

Quantifying the hydrological effects of stream restoration in a montane meadow,northern California,USA

Stream restoration efforts, particularly within meadow systems, increasingly rely on ‘pond and plug’ type methods in which (a) alluvial materials are excavated from the floodplain, forming ponds; (b) excavated alluvial materials are used to plug incised channels and (c) smaller dimension channels are restored to the floodplain surface. A commonly stated objective of these efforts is to restore ecologically significant hydrological processes to degraded riparian systems. However, little research has been conducted to evaluate and quantify the restoration of these hydrological processes. Direct comparisons of pre‐ and post‐restoration hydrological observations are often misleading due to an inter‐annual climatic variability. To overcome this issue and accurately quantify the hydrological effects of restoration, we developed, calibrated and validated a hydrological model of a 230 ha mountain meadow along a 3.6 km restored reach of Bear Creek in the northeastern California. We then applied the model to simulate the pre‐ and post‐restoration scenarios by altering the floodplain topography and stream channel networks. Our results document three general hydrological responses to the meadow restoration effort: (1) increased groundwater levels and volume of subsurface storage; (2) increased frequency/duration of floodplain inundation and decreased magnitude of flood peaks and (3) decreased annual runoff and duration of baseflow. This study supports and quantifies the hypothesis that ‘pond and plug’ type stream restoration projects have the capacity to re‐establish hydrological processes necessary to sustain riparian systems. In addition, the results of this study can be used to improve quantitative objectives for ‘pond and plug’ type stream restoration activities in similar settings. Copyright © 2008 John Wiley & Sons, Ltd.     

The Hydrological Status Concept: Application at a Temporary River (Candelaro,Italy)

In achieving the final objective of the European Water Framework Directive, the evaluation of the ‘hydrological status’ of a water body in a catchment is of the utmost importance. It represents the divergence of the actual hydrological regime from its ‘natural’ condition and may thus provide crucial information about the ecological status of a river. In this paper, a new approach in evaluating the hydrological status of a temporary river was tested. The flow regime of a river has been classified through the analysis of two metrics: the permanence of flow and the predictability of no‐flow conditions that were evaluated on monthly streamflow data. This method was applied to the Candelaro river basin (Puglia, Italy) where we had to face the problem of limited data availability. The Soil and Water Assessment Tool model was used when streamflow data were not available, and a geographic information system procedure was applied to estimate potential water abstractions from the river. Four types of rivers were identified whose regimes may exert a control on aquatic life. By using the two metrics as coordinates in a plot, a graphic representation of the regime can be visualized in a point. Hydrological perturbations associated with water abstractions, point discharges and the presence of a reservoir were assessed by comparing the position of the two points representing the regime before and after the impacts. The method is intended to be used with biological metrics in order to define the ecological status of a stream, and it could also be used in planning the ‘measures’ aimed at fulfilling the Water Framework Directive goals. Copyright © 2014 John Wiley & Sons, Ltd.     

VEGETATION–LANDFORM ASSEMBLAGES ALONG SELECTED RIVERS IN THE CZECH REPUBLIC,A DECADE AFTER A 500‐YEAR FLOOD EVENT

Rivers with a natural flow regime strongly influence the dynamics of riparian plant communities through hydrological and geomorphological processes. In this study, associations between fluvial landforms and vegetation are investigated on three near‐natural rivers in the Czech Republic a decade after a 500‐year return period flood in July 1997. This extreme disturbance destroyed the anthropogenically modified river channels and created suitable conditions for a range of ecosystems with high diversity and ecological stability. Field surveys were conducted on fluvial landforms (bars, islands, banks, floodplains and terraces) along three ‘renaturalized’ rivers, where no technical modifications had subsequently been made to their channels outside urban areas and the floodplains had been left in a post‐flood state. Vegetation species abundance and 13 environmental variables (topographical, hydrological and soil) were investigated in summer 2007, 10 years after the extreme flood disturbance. The results suggest that the recently created fluvial geomorphic forms are key environmental determinants of riparian vegetation distribution patterns. A range of statistical analyses illustrate that some plant species show predictable patterns of occurrence that correspond with the fluvial forms, supporting a fourfold grouping of herbaceous and woody species and the identification of typical plant communities associated with gravel bars, islands, banks, floodplains and terraces. An investigation of the species richness found on different fluvial landforms showed that the highest number of species occurred on the floodplain and decreased gradually towards the channel bed and towards terraces. Investigation of existing conditions in reaches of rivers with natural dynamics of fluvial processes provides valuable information that can be used as an effective tool for planning restoration strategies and precise management. However, the most important finding of this study is the remarkable establishment of complex river corridor vegetation–landform associations within 10 years of a 500‐year flood that removed the heavily cultivated landscape that had existed before the event. Copyright © 2011 John Wiley & Sons, Ltd.     

The flood of the century on the River Oder: effects on the 0+ fish community and implications for floodplain restoration

In summer 1997, the flood of the century occurred on the River Oder in the Czech Republic, Poland and Germany. Effects of the summer flood on the 0+ fish community were evaluated at the Lower Oder in the Polish–German National Park. Fish were collected from different mesohabitats before the flood, at rising water levels and after the flood using Point Abundance Sampling by electrofishing. Flooding caused changes in local 0+ fish assemblages and partly affected the physical habitat structure. Two sandbars were formed by breaches in the dike system, replacing the former uniform river embankments. Under post‐flood conditions, diversity was increased in nearly all mesohabitats. ‘Wash‐out’ of 0+ fish was highest in poorly structured mesohabitats. Effects of the summer flood on eurytopic species were the most pronounced. We suggest that the progeny of rheophilic species were affected to a lesser extent by flooding because of their adaptation to variable flow conditions. Furthermore, rheophilic 0+ fish were able to colonize the newly created mesohabitats and, thus, benefited from the increased habitat heterogeneity after the flood. In this context, implications for floodplain restoration are discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

FISH HABITAT OPTIMIZATION TO PRIORITIZE RIVER RESTORATION DECISIONS

This paper examines and ranks restoration alternatives for improving fish habitat by evaluating tradeoffs between fish production and restoration costs. Optimization modelling is used to maximize out‐migrating coho salmon (Oncorhynchus kisutch) from a natal stream and is applied as a case study in California's Shasta River. Restoration activities that alter flow and water temperature conditions are the decision variables in the model and include relocating a major diversion, increasing riparian shading, increasing instream flow, restoring a cool‐water spring and removing a dam. A budget constraint limits total restoration expenditures. This approach combines simple fish population modelling with flow and water quality modelling to explore management strategies and aid decision making. Previous fish habitat optimization research typically uses single restoration strategies, usually by altering reservoir releases or modifying outlet structures. Our method enlarges the solution space to more accurately represent extensive and integrated solutions to fish habitat problems. Results indicate that restoration alternatives can be prioritized by fish habitat improvement and restoration cost. For the Shasta River case study, considerable habitat restoration investments were required before fish productivity increased substantially. This exercise illustrates the potential of ecological optimization for highlighting promising restoration approaches and dismissing poor alternatives. Copyright © 2011 John Wiley & Sons, Ltd.     

Analysis of changes in flood regime using a distributed hydrological model: a case study in the Second Songhua River basin,China

Abstract

This study proposes and tests a new approach to detect and analyze changes in flood regime using a distributed hydrological model (EasyDHM), using the Second Songhua River basin, China, as a case study. Model calibration and parameter sensitivity were used to represent flood regimes in a 60-year series (1954–2013), with three different flood regime periods identified. The changes in flood regime were estimated by model parameters, flood result residuals and the overall process in the hydrological model in the three periods. The results show that human activities significantly impacted flood regimes, with significant flood regime change largely attributed to increases in water storage in multiple small reservoirs. Flood volume was reduced significantly between the periods in all three watersheds. The parameters also changed in variety between the periods. The study highlights the importance of incorporating data on small-reservoir constructions in flood control systems.     

Long‐term Hydrologic Variability in a Large Subtropical Floodplain River: Effects on Commercial Fisheries

We analysed the effects of decadal and annual hydrologic fluctuations on freshwater fisheries catches in the Middle Paraná River for a period of six decades from the 1930s to the 1980s. The climatic fluctuations in this period strongly affected the hydrology of the Middle Paraná River and the characteristics of its flow regime. The magnitude of floods as well as maximum, minimum and mean water levels increased progressively from 1930s until the 1980s concomitantly with increasing frequency and intensity of El Niño Southern Oscillation events that resulted in differentiation of distinct hydrological periods. The flood pulses were significantly more frequent and of greater magnitudes during the 1970s and 1980s. These large floods resulted in increased commercial fish catches in the 1980s, possibly because of enhanced recruitment. Specifically, large floods increased the commercial fish catches 2 years later. This effect was stronger for species that use floodplain habitats as areas of reproduction and larval nurseries, such as Prochilodus lineatus. We conclude that the natural flow regime of the Paraná River and perhaps other large subtropical rivers must be preserved in order to sustain their productive fisheries. Copyright © 2016 John Wiley & Sons, Ltd.     

1956-2019年乌江水文情势变化及其对鱼类的影响研究

水量变化导致河流生态水文情势发生改变,进而影响河流生态系统健康。为深入明晰乌江干流水文变异前后水文情势变化对鱼类生境的影响,选取武隆水文站1956-2019年逐日流量数据及2009-2015年12种漂流性鱼类产卵量资料,采用曼-肯德尔 (M-K)检验法、累积距平法研究乌江干流变异节点,分析突变前、后逐日流量的变化趋势,通过生态水文指标变化范围法(IHA-RVA)综合评价乌江32组水文指标特征及改变度,基于水文情势变化下研究鱼类数量变化过程。结果表明：乌江流量突变年份为2009年,与彭水水电站的运行时间相同,变异后,多年平均日流量峰值波动于15 000 m³/s,而变异前流量峰值接近18 000 m³/s。乌江32组水文指标整体改变度为38.7%,处于中度变化范围;属于高度改变的低流量历时和次数改变度分别为74.64%、75.29％,发生时间推迟4 d;高流量历时和次数改变度分别为29.79%、37.83％,发生时间提前21 d。降雨与流量呈极强正相关,降雨量的逐年减少对流量有重要影响。此外,水文情势的变化易受彭水水电站的影响。流量减少和变化下的水文情势对鱼类的影响是一个累积的过程,2009年后12种漂流性卵鱼类的产卵总量大幅减少,尤以2011年最为突出,仅为1 541.69×10⁴粒。本研究可为研判乌江水文情势变化过程及制定水生态修复措施提供参考。     

岷江下游航电梯级生态流量协同造峰调度研究

岷江下游4个水电梯级的开发将对最下游梯级水电站(龙溪口)坝址下长江上游珍稀、特有鱼类国家级自然保护区内的重点保护鱼类产卵、繁殖关键生命周期的洪峰流量过程产生影响。因此,有必要开展梯级电站生态流量联合调度研究。研究认为,在鱼类产卵高峰期的7~8月,梯级电站可分预泄-敞泄-回蓄3个阶段实施造峰调度,老木孔,东岗岩,犍为和龙溪4个梯级同步敞泄,保证洪峰顺利通过各梯级,维持下游天然水文过程;洪水过后,采取专门的调度措施回蓄,延长回蓄时间,保证退水过程与天然洪峰保持基本一致,避免造成下游减脱水过程。研究方案的实施可为下游长江珍稀特有鱼类提供类似天然的水文过程,减轻水电梯级开发对鱼类产卵的影响。     

MORPHOLOGICALLY RELATED INTEGRATIVE MANAGEMENT CONCEPT FOR RECONNECTING ABANDONED CHANNELS BASED ON AIRBORNE LiDAR DATA AND HABITAT MODELLING

Most of the large rivers are heavily degraded and lack near‐natural conditions due to high human pressure (agricultural use and settlements) especially on former inundation areas. Hence, it is rarely possible to ‘restore’ predisturbance conditions of rivers and their floodplains. Further, river or floodplain restoration programs are often based on type‐specific reference conditions. Those reference conditions are mainly determined on the basis of historical maps not giving any information of, for example, sediment supply, flood frequency and vegetation cover (density). Especially for improving the ecological status of rivers with abandoned channel features, key habitats for target fish species have to be restored by reconnecting floodplains and their secondary channel system. In addition, because of the necessity of improving the ecological status, there is growing interest in interdisciplinary river restoration techniques. Within the presented article, an integrative concept is derived based on Light Detection and Ranging measurements and numerical modelling with respect to river dynamics (hydrologic and morphological). Further habitat modelling, based on unsteady depth‐averaged two‐dimensional hydrodynamics, is applied with a focus on the mesounit scale. For testing the conceptual model, various river reaches at the Morava River were selected, featuring different morphological characteristics. It was found that the applied management concept allows considering the important issues of river dynamics (morphological/hydrologic) using a flow‐ and flood‐pulse approach for identifying bottlenecks of target species at the Morava River. The reconnection of abandoned channels will result in an increase of hydromorphological heterogeneity and/or woody debris within the study reach. This might be of high relevance for habitat features (e.g. backwater habitats) especially for flow pulses between low flow and mean flow and/or in reaches without abandoned channels between low‐flow and the bankfull stage. Copyright © 2012 John Wiley & Sons, Ltd.     

Auenrevitalisierung – Potenzial und Grenzen am Beispiel der Lobau, Nationalpark Donau-Auen

What is now Vienna’s Lobau floodplain is a remnant of a much larger, dynamic floodplain region on the left bank of the Danube. Efforts to regulate the river’s flow in the late 19th century resulted in an almost complete separation of the area from the main channel, and the resultant hydrological and ecological deficits call for sustainable revitalization measures for the Lobau that preserve the area’s high natural value and support a stronger hydrological dynamic closer to its original character, without sacrificing essential current forms of use like flood protection and drinking water production. In the following, various already completed and planned remedial measures for the Upper and Lower Lobau are presented, and their effects on the area in question, their potential but also their limitations with regard to restoring the dynamic of the floodplains and lastingly reversing local processes are discussed. The revitalization project for the Upper and Lower Lobau pursues a conservation-based approach that is above all intended to compensate for hydrological deficits in the extremely degraded Upper Lobau and safeguard the status quo there. Initial research results are promising, confirming positive effects on water quality and habitats in the Upper Lobau. Given the increased water levels, the efforts planned for the Lower Lobau will at least generate a certain dynamic in its upper range (moderate floodplain revitalization). However, a far-reaching reversal of the processes currently at work in the Lower Lobau will require large-scale revitalization efforts that secure a dynamic linking of the area to the Danube, including periodic high flow-through rates; these in turn will support morphological redistribution processes, initiating broad-scale and lasting habitat changes.     

一种新的水文情势改变度综合估算法

基于 33 个水文改变指标,分别采用变化范围法、直方图匹配法、直方图比较法和修正变化范围法 4 种方法, 计算汉江中下游黄家港水文站的水文变异性,并对比分析各方法的优缺点。变化范围法忽略了水文指标在极值 和目标范围的具体变化;直方图匹配法和比较法考虑了水文指标在各范围的分布;修正变化范围法涵盖了形态变 化的概念。通过主客观组合赋权,融合直方图比较法和修正变化范围法的结果,提出一种新的综合估算法,既保 留水文情势的分布、频率和时空变化信息,又避免数据冗余。综合估算法结果表明：各月月均流量和极端流量大 小的改变度均为中度改变,分别为 41.28% 和 64.83%;流量增减变化率的改变度为高度改变（80.53%）;汉江中下游 水文情势的整体改变度为中度改变（55.70%）。该法可降低计算结果的不确定性,避免水文变异性结果出现异常, 从而更加合理可靠。     

Habitat time series analysis to define flow augmentation strategy for the Quinebaug River,Connecticut and Massachusetts,USA

We developed a habitat augmentation strategy for the Quinebaug River (Connecticut and Massachusetts, USA) in order to reduce impacts on fish habitat, water temperature and pollutant concentrations attributable to consistently low water flows. Using the MesoHABSIM approach and a uniform continuous under‐threshold (UCUT) analysis of simulated habitat time series, we determined allowable periods of low‐flow conditions that follow natural patterns. The amount of water necessary to achieve the required habitat levels was calculated for various river restoration scenarios. We also created a set of detailed rules for a habitat augmentation release that applies short ‘pulses’ of water to increase habitat availability and mitigate the effects of persistent drought conditions. A set of flow chart templates was developed to guide the planning of an augmentation scheme by utilizing flow releases from reservoirs. To test our augmentation procedures, we performed evaluation tests by applying the rules to flows that occurred in 1994 (a drought year). The test showed that the number of flow interventions necessary was limited, underlining the feasibility of a pulse‐based approach. Copyright © 2008 John Wiley & Sons, Ltd.     

武烈河口滦河段防洪治理与效益分析

通过武烈河口滦河段人工修复措施,对武烈河口滦河段洪水设计,根据上游水文站系列资料,采用洪水过程错时段迭加的方法,计算出设计断面的设计洪水。采用不同方案对比的方法,确定出最优断面300m宽度设计洪水位。经过治理后的武烈河口滦河段,达到了动、静结合,自然环境和人文环境的和谐统一,建设了橡胶坝和观光桥生态工程,既有实用性,又突出了观赏性和生态功能。     

The ‘natural flow paradigm’ and Atlantic salmon—moving from concept to practice

The ‘natural flow paradigm’ is becoming an important first principle in the setting of managed flow regimes throughout the world, including Canada. The principle states that managed flow regimes should consider the natural hydrological variability of a river system, both seasonally and interannually, to maintain its ecological integrity. While laudable, this principle is in direct conflict with hydropower development and irrigation interests. Therefore, both regulatory agencies and developers are struggling to identify the elements of hydrological variability that are critical to maintain the ecological health of rivers. In this paper, we identify flow requirements for different life stages of anadromous Atlantic salmon (Salmo salar L.). We then explore the potential effects of different flow regime scenarios on a wild Atlantic salmon population, using Harry's River in Western Newfoundland as an example. First, we link the life history patterns of Atlantic salmon to the scenario of the natural hydrological variability, incorporating the flow requirements for migration, spawning and rearing. In a second scenario, we present a flow regime managed for optimal hydropower production. Finally, we propose a conceptual model for a hypothetical managed flow regime that provides the necessary hydrological flow variations to support the life history requirements of Atlantic salmon, while permitting flow regulation and modification. This exercise identified data gaps and further research needs. Particularly, more information is needed on the amplitude of spring flooding necessary to initiate downstream migration while minimizing spill, which could potential be used for hydropower production. Copyright © 2008 John Wiley & Sons, Ltd.