The current state of the use of large wood in river restoration and management

Trees fall naturally into rivers generating flow heterogeneity, inducing geomorphological features, and creating habitats for biota. Wood is increasingly used in restoration projects and the potential of wood acting as leaky barriers to deliver natural flood management by ‘slowing the flow’ is recognised. However, wood in rivers can pose a risk to infrastructure and locally increase flood hazards. The aim of this paper is to provide an up‐to‐date summary of the benefits and risks associated with using wood to promote geomorphological processes to restore and manage rivers. This summary was developed through a workshop that brought together academics, river managers, restoration practitioners and consultants in the UK to share science and best practice on wood in rivers. A consensus was developed on four key issues: (i) hydrogeomorphological effects, (ii) current use in restoration and management, (iii) uncertainties and risks and (iv) tools and guidance required to inform process‐based restoration and management.     

A decision support system for identifying the habitat quality and rehabilitation potential of urban rivers

Few habitat survey, classification or assessment methodologies have been developed specifically for urban or heavily engineered rivers, and yet these rivers need careful assessment if management options are to be considered and prioritised in an economically and environmentally effective way. This paper presents a refinement of a previously proposed urban river survey (URS), which is a modification of the Environment Agency's River Habitat Survey. It then describes indices and classifications that have been developed from URS data and that provide a link between the type of engineering applied to a stretch of urban river and its habitat characteristics. Finally, some simple decision trees and scenario‐modelling tools are presented that allow (i) newly surveyed urban stretches to be classified and (ii) some simple scenarios of channel management change to be assessed in order to prioritise management options for stretches of urban river across urban catchments.     

CHARACTERISTICS AND CONTROLS OF GRAVEL-BED RIFFLES: AN ANALYSES OF DATA FROM THE RIVER-HABITAT SURVEY

This paper presents an analysis of data from the UK Environment Agency's River Habitat Survey database relating to bedform type and frequency. Emphasis is given to the gravel-bed riffle which (a) traditionally has been considered to be a fundamental morphological unit diagnostic of river stability, and (b) more recently has become an important design component in channel restoration and rehabilitation schemes. Data were sufficient to support the identification of distinct, catchment-scale controls determining the circumstances under which step-pools and riffles occur, and key local-scale influences upon riffle frequency and spacing. This demonstrates that the database can be used to support a broad geomorphological analysis. Suggestions are made for the interpretation of results obtained from the existing database, and for possible future modifications to enhance its geomorphological value.     

万里碧道：习近平生态文明思想的广东生动实践

治水兴水是习近平生态文明思想的重要内容。高质量规划建设万里碧道代表着广东在生态文明背景下系统治水兴水的新方向。为全面介绍和展现广东万里碧道规划建设的丰富理念内涵,本刊编辑部以"万里碧道"为主题组织学术笔谈,邀请了9位专家学者就万里碧道规划建设的理念、目标、任务、方法等方面进行探讨。作为10年前广东绿道和现在万里碧道总体规划的项目总负责,马向明认为绿道作为广东将生态修复与社会服务功能相结合的大型网络连接工程,开启了广东线性开敞空间的建设;碧道以流域为单元,将治水与治岸结合,营建功能复合的河流廊道,促进沿线社会-自然系统的优化调整与耦合。碧道既是绿道经验的继承和发扬,又进一步延伸拓展,碧道在功能上更为复合、在协同制度上进行了创新、在理念上引入了时间维度。从绿道到碧道,展现了广东线性开敞空间建设从网络连到系统耦合的发展。邱衍庆谈及广东万里碧道规划建设以保护与恢复河流自然生态为首要原则,通过明确万里碧道建设负面清单,结合不同碧道类型因地制宜发挥人工力和自然力,引入时间维度强调分阶段推进碧道建设等方式,做到"守住自然生态安全边界,建设人与自然和谐共生的万里碧道"。同样聚焦于碧道水生态保护与修复,...     

Retrieval of suspended particulate matter concentrations in the Danube River from Landsat ETM data

Alternations in river channel morphology result in a disturbed natural transport of suspended particulate matter (SPM). Suspended particulate matter serves as a transport medium for various pollutants, e.g. heavy metals. It is therefore important to understand how artificial obstructions alter the natural transport of suspended matter. Measurements of SPM in rivers are traditionally carried out during in situ sampling campaigns, which can provide only a limited view of the actual spatial distribution of suspended matter over large distances. Several authors have studied how space-borne remote sensing could be used for mapping of water quality in standing waters, but with only little attention paid to rivers. This paper describes the methodology how a Landsat ETM image was used to map the spatial patterns of SPM in the Slovak portion of the Danube River. Results of our investigation reveal that the Danube River in Slovakia exhibits gradual longitudinal decrease in concentrations of SPM. Based on a strong relationship between the Landsat near-infrared band (TM4) and field measurements, we developed a map of suspended particulate matter in the Danube River with a standard error (SE) of 2.92 mg/L. This study aims to show how archived satellite data and historical water quality data can be used for monitoring of SPM in large rivers. A methodology describing the minimum samples required for sufficiently accurate results is discussed in this paper also.     

Impacts of River-Engineering Practices on the Conservation Interest and Water Quality in the Land Yeo, England

The environmental quality of many rivers on the Somerset Levels and Moors has been reduced because of past river-engineering practices and changes in land use. A new holistic and restorative approach to river management is now helping to improve the quality of aquatic ecosystems. This paper presents the results of a study which assessed the impact of past river and floodplain management on the Land Yeo, Somerset, with the objective of recommending measures for future management. The main findings are that (a) the ecological interest of the river has been reduced due to channel re-sectioning and flow diversion, and (b) the flow diversion is also causing water-quality problems such as dissolved-oxygen reduction. Most of this degradation could be reversed by the adoption of a number of channel and riparian-enhancement measures and by revising the annual maintenance programme.     

Rivers and river restoration: a child's-eye view

Research suggest a high level of interest in the environment and in environmental action by children. Yet very little is known about how children perceive the natural environment. Despite the fact the children are one of the largest user groups of outdoor spaces, their views are rarely sought. The aim of this small qualitative study was to look at children's perceptions of river corridor environments, and specifically to look at their views on restoring our rivers. The children demonstrated a strong concern for the natural environment and supported the idea of river restoration. Natural features of river corridor landscapes were valued, but the children also valued highly other non-natural features which afford them opportunities for play and exploration. By talking to children, and also by analysing children's drawings and writings about rivers, the study aimed to gain a broader understanding of how children perceive the river environment, and how they might participate more fully in its management.     

荆门市竹皮河流域水环境综合治理之生态修复工程设计

竹皮河为季节性雨源型城市河流,存在污水直排、底泥淤积、季节性干涸等诸多水环境问题,导致其水质恶化严重,水生态系统受损,自净能力较弱。为恢复竹皮河生态系统多样性,提升水体自净能力,实现水质长效保持,在控源截污的基础上,采用人工湿地、原位微生物修复、生态砾石河床、水生植物恢复等多种生态治理技术集成,实施河道生态补水、生态净化、生态修复三大工程,重建生态系统多样性,实现水质自然净化。通过流域综合治理,竹皮河城区段下游水体水质逐步达到地表Ⅳ类水标准。工程设计为雨源型城市河流的生态治理提供了参考。     

基于河流生境恢复的河流景观设计——以重庆肖家河为例

探索河流生境的基本结构,研究河流生境结构与河流景观功能之间的关系,有利于创造一种接近自然的河流景观,为建设人类与自然并存的河流新景观有积极的意义。本文通过重庆肖家河景观设计实践,在解析河流生境的概念、内涵和基本结构特征的基础上,讨论恢复河流生境在河流景观设计中的具体应用。     

城市规划中应构造生态的河涌水网--以广州河涌断面的设置形式为例

广州市现有的大部分河涌断面形式设计忽视河涌的景观功能。城市规划中应建设多自然河流,河流平面定线设计应尽量保持原有河道;河道横断面设计应形成滩涂、水潭置水域到陆地的过渡带;针对河涌的实际情况,采用不同的断面设计。     

堤岸下的景观——大田均溪滨水景观带方案设计

在城市化扩展过程中，那些自然河道的渠化和硬化在中国大小城市中方兴未艾，出于河流防洪工程的建设需要，河岸两侧被高而垂直的堤岸所割裂。河流丧失了自然属性，并对环境造成不利的影响，这个案例试图说明针对现状滨水两岸道路狭窄，如何在甲方要求不破坏现状防洪堤岸工程情况下，对其进行设计，使这昔日可达性极差的滨水带，变成令人流连忘返的城市游憩地，重心唤起人们内心深处对生活的原初感受和对场地空间所带来的乐趣，创造一种当代人的景观体验空间。     

A conceptual model of riparian forest restoration for natural flood management

There is an increasing emphasis on using natural processes, including riparian forest restoration, to enhance the ecological, hydrological and geomorphological functioning of watercourses. However, we have insufficient knowledge on how the supply and retention of in‐channel wood from riparian forest stands changes with age, with inferences typically based on data from terrestrial forests. This presents a challenge in estimating the efficacy and functional lifespan of restoration projects. In this paper, we use a riparian forest growth model to show there is a lag of up to 40–50 years between the start of forest growth and trees delivering wood to the channel that is large enough to resist fluvial transport, anchor logjams and so increase channel complexity and hydraulic resistance. Resource managers need to account for realistic timescales over which changes promoted by riparian woodland restoration will occur and may need to consider using interim engineered logjams as the forest develops.     

Engineering geomorphology: A UKuk perspective

Engineering geomorphology has developed at a rather disappointingly slow rate in the UK since publication of the earlier applications in the 1970’s. Among the more notable contributions of geomorphological techniques and expertise to civil engineering have been the various landslide mapping surveys carried out for road construction projects overseas and in the UK. However, while geomorphological mapping has proved to be a useful tool for landslide assessment and the planning of geotechnical ground investigations there are four main constraints that currently limit the professional application of engineering geomorphology to civil engineering practice. First, the subject has not received universal acceptance by civil engineers who often see it as too academic and not directly applicable to engineering design. Second, when geomorphological mapping has been used it has often been applied at the beginning of a project and frequently continual geomorphological interpretation is not allowed to take place as the geotechnical ground investigation and design take place. Third the technique of geomorphological mapping is the most familiar geomorphological tool known to the civil engineer and the valid and often cost-effective contributions that geomorphologists can make to other civil engineering studies using different techniques are frequently not recognised. Finally, so-called engineering geomorphologists trained in the UK often do not have sufficient knowledge of engineering design criteria to be gainfully employed on civil engineering projects. Some of these problems may be resolved by a reconsideration of the training given to potential engineering geomorphologists in the UK, possibly by the British Geomorphological Research Group and the Engineering Group of the Geological Society, and a greater awareness among civil engineers of the full potential that engineering geomorphology can offer.     

基于地域文化的城镇小河道景观设计——以浙江杭州萧山区江东直河景观设计为例

水是生命之源,河道是大地的血脉,是维持大地景观生态系统结构的重要要素,是维系社会生活和生产功能的重中之重。当前城镇的小河道治理仍停留在防洪排涝、灌溉水利等传统基础功能上,河道景观建设面临着景观特色趋同、地域景观差异消失、生态环境破坏等问题。河道治理在历经截污、清淤、底泥处理、护岸修复等一系列措施之后,河道景观也应该逐渐被重视,做到功能和景观相得益彰。     

Hydrology and the ecological quality of Scottish river ecosystems

Hydrology is a primary control on the ecological quality of river systems, through its influence on flow, channel geomorphology, water quality and habitat availability. Scottish rivers are widely perceived to be of high ecological quality, with abundant flow volumes and high water quality. However, historical and current river flow regulations, and land use change have altered the physical and chemical characteristics of Scottish rivers, with adverse consequences for aquatic biota. Baseline hydrological, geomorphological and water quality conditions in Scottish rivers are thus summarised. The impacts of river regulation and land use change on the hydrology, geomorphology and water quality of Scottish rivers are then discussed. Consequences of these changes for aquatic habitat are examined, with particular reference to the economically significant salmonid species (Salmo salar and Salmo trutta). Policy and management issues relating to the future ecological quality of Scottish rivers are reviewed. These include the impacts of climate change on ecological quality, the calculation and implementation of ecologically acceptable flows, and river restoration and best management practices within integrated catchment planning.     

Aesthetic preferences versus ecological objectives in river restorations

Restoring rivers has become a common practice in the management of natural resources. While the ecological rehabilitation of river corridors is a clear objective for project planners, it cannot necessarily be assumed that the public will perceive the effects to be aesthetically positive. To assess people's perceptions of the visual attractiveness of restoration scenarios, we conducted a representative Switzerland-wide survey using photographic simulations and related the reported preferences to experts’ assessments of the ecological integrity of these scenarios based on eco-morphological criteria. We further considered how natural the public perceived river corridors to be and how much these corridors satisfy public needs. The results of the survey show that aesthetic preferences relate more positively to eco-morphological quality than expected, and that the public's aesthetic preferences are primarily influenced by perceived naturalness. Even slightly improved eco-morphological quality was rated higher aesthetically, which suggests that the aesthetic outcomes of even small efforts to restore rivers are viewed positively by the public.     

Restoration of a chalk stream using wood: assessment of habitat improvements using the Modular River Survey

The installation of large wood and sediment berms to narrow the overwide channel of the River Bulbourne, Hertfordshire, aimed to restore geomorphological processes, improve channel habitat diversity and increase the amenity value of the park in which the river is located. The Modular River Survey provides a framework and suite of tools for river managers and volunteers to monitor and assess restoration activities. Applying this technique to the River Bulbourne before and after restoration demonstrated that the works increased physical habitat and vegetation complexity. The restored section was narrowed, substrate composition changed and the range of in‐stream vegetation morphotypes increased. The initial slight improvement in riparian habitat complexity immediately following the restoration is expected to increase further over time as the riparian vegetation develops and the restored section of channel matures. A public perception and recreational use survey reviewed how visitor experience and use of the park changed following restoration.     

河段尺度下的城市渠化河道近自然化策略研究

河流近自然化治理的理念正在逐步拓展和实现,对于仍在高速发展的中国来说,预示着传统的技术手段到了需要革新的时代。河流系统是多重等级系统,本文选取河段尺度的城市渠化河流作为研究对象,确定渠化河流的形态特征、功能特征和空间特征,并以此将渠化河流分为3类,即空间紧缩的、有弹性余地的和有较大空间拓展的河道。论文基于大量的基础研究和工程考察,对应3类河道,创新的提出城市紧缩型河道策略、城市弹性型河道策略和城市开拓型河道策略。该策略体系的总结是应对未来中国城市渠化河流改造趋势的一个重要的探索与努力。     

Environmental change in river channels: a neglected element. Towards geomorphological typologies,standards and monitoring

Rivers integrate the impacts of change in atmospheric and terrestrial systems; they then deliver these to the coast. En route geomorphological processes create dynamic and diverse habitats, both in-stream and in riparian/floodplain ecotones. The dynamics of channel change conflict with human resource development, the outcome is that many river and riparian environments have been significantly modified, complicating the interpretation of change. Collection of geomorphological data on both form and process has to date been overwhelmingly an academic pursuit; standard measurement networks and long-term monitoring have, as a result been largely absent-as in the Environmental Change Network (ECN), despite the emerging requirements of legislation such as the EU Water Framework Directive. In this paper, we utilise a unique set of repeat channel surveys and long-term bed-load sediment yields to provide guidance on both definitions of change and those variables and survey techniques which might form the basis, in future, of improved national-scale monitoring. The Environment Agency's River Habitat Surveys suggest the basis for channel typologies that could structure a sampling framework and rationalise the variables to be monitored. We also point to the value of more detailed geomorphological procedures in use at the catchment/project scale-Catchment Baseline Surveys and Fluvial Audits-as a standardised basis for monitoring the detail of change in the fluvial sediment system. A perfect opportunity to lay foundations for such monitoring activity has been provided in England and Wales by the winter floods of 2000/2001.