A preliminary pressure–impact analysis applied in the Pinios river basin (Thessaly, Central Greece)

Greece has not yet undertaken one of the first and most important tasks required by the Water Framework Directive (WFD: the integrated review of the impact of human activity on the status of surface waters for each river basin – the IMPRESS analysis. Owing to the lack of a national methodology, a preliminary analysis was carried out for the Pinios river basin, applying a combination of different methodologies refined to suit the particularities of the Greek freshwater environment and to accommodate the limited availability of data. Pressures caused by the main pollution sources, point and nonpoint, were quantified in terms of pollution loads with the use of emission factors. The existing limited biological and physicochemical monitoring data were used to assess impacts. Additionally, we identified pressures caused by alterations from land-use data; we carried out a River Habitat Survey (RHS) and estimated the hydromorphological impacts through the calculation of a Habitat Modification Score (HMS). Our results suggest that the probability of the Pinios river basin failing to achieve good ecological quality by 2015 due to pollution is high, and due to hydromorphological pressures is moderate.     

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.     

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.     

Trends in the use of large wood in UK river restoration projects: insights from the National River Restoration Inventory

Large Wood (LW) is increasingly employed in river restoration to promote physical habitat heterogeneity and ecological diversity. To explore how LW has been used in restoration schemes across the United Kingdom in recent decades, we analysed data on 912 LW projects archived in the UK’s National River Restoration Inventory (NRRI). The number of LW schemes has continued to increase following the earliest records in the 1990s, largely tracking overall trends in river restorations. LW projects have been predominantly located in lowland, rural streams, although there has been a notable cluster in and around London. LW projects have mainly revolved around the desire to deliver hydromorphological improvements and specifically the creation of fish habitat. Most schemes used LW in simple deflector forms despite the growing scientific evidence of the benefits of using structurally complex LW. Post project monitoring has been limited and mostly restricted to photographic records. This type of database analysis can provide important insights and help guide future restoration practice.     

A decision support system for water quality issues in the Manzanares River (Madrid, Spain)

The Manzanares River, located in Madrid (Spain), is the main water supplier of a highly populated region, and it also receives wastewater from the same area. The effluents of eight Waste Water Treatment Plants (WWTPs) downstream of the river, which represent 90% of the flow in the middle and lower parts of the river, are the primary sources of water pollution. Although the situation has improved slightly in the last two years, the water in the river is highly polluted, making it uninhabitable for aquatic life. Water quality modelling is typically used to assess the effect of treatment improvements in water bodies. In this work, the GESCAL module of the Aquatool Decision Support System Shell was used to simulate water quality in the Manzanares River. GESCAL is appropriate for modelling in an integrated way water quality for whole water resources systems, including reservoirs and rivers. A model was built that simulates conductivity, phosphorous, carbonaceous organic matter, dissolved oxygen, organic nitrogen, ammonia, and nitrates. The period from October 2006 to September 2008 was selected for calibration due to the many treatment modifications that occurred during this time. An earlier and longer period, from October 2000 to September 2006, was used for validation. In addition, a daily model was used to analyse the robustness of the GESCAL model. Once the GESCAL model was validated, different scenarios were considered and simulated. First, different combinations of nutrient elimination among the different WWTPs were simulated, leading to the conclusion that investments have to focus on three of the proposed WWTPs. Moreover, these treatments will not be sufficient to maintain fish habitat conditions at all times. Additional measures, such as the increment of the flow in the river or oxygen injection, were simulated. Incrementing the flow of the Manzanares River has been shown to be an efficient means of increasing water quality, but this implies an increment in the risk of water scarcity situations in the Madrid water supply system.     

Algal diversity in relation to water quality in an Indian river

The application of the two diversity indices (Shannon's index of diversity and Margalef s index of diversity) has been critically analysed for water pollution monitoring in the tropical polluted river Khan. These two indices can be usefully employed for the biological assessment of water quality in tropical polluted rivers.     

基于河流动态自然过程的生境修复策略

全球气候变化和土地利用方式的改变对河流的动态自然过程带来不利影响。而目前人们对河流的修复重治理效果而轻自然过程,特别是风景园林与相关学科的交叉与融合研究较少,缺乏聚焦中、微尺度基于河流动态自然过程的生境恢复方法指导。基于此,从雨洪淹没、潮汐消落的河流动态自然过程规律着眼,提出对应的生境修复策略：1)恢复水陆边界的自然属性,重建泛洪区和河岸的联系;2)梯度式快速恢复近自然河岸带生境植被;3)连通感潮河涌湿地和营建关键生物生境,实现多种共生生物栖息地的再生。该方法有助于恢复河流长期、稳定的自由流动,生境在河流动态潮汐作用下异质性不断提高,从而提高河流湿地的生物多样性,还能为城市中心的居民提供亲近自然的休闲空间,以期在河流生境修复实践方面为风景园林和多学科融合提供新思路。     

高铁对沿线野生动物空间分布的影响 特征及生境适宜性评价——以京广高铁 武汉乌龙泉段为例

高铁作为中国重要的交通基础设施,其建设和运营 不可避免会对沿线环境造成不同程度的影响。解析高铁对沿线 生境的干扰特征,是实现沿线野生动物保护的重要途径。基于 京广高铁武汉乌龙泉段乡野样本地的长期红外相机监测结果, 分析高铁对沿线野生动物空间分布的影响特征,并筛选出当地 陆地野生动物代表物种小麂,提取其分布点数据,利用最大熵 (MaxEnt)模型预测小麂生境适宜区分布,分析气候、地形、 人类干扰和水源4类环境变量的影响程度。结果表明：1)高 铁对狗獾和黄鼬造成空间阻隔效应显著;2)小麂、白鹇、黄 鼬、狗獾和貉均对高铁产生回避效应;3)代表物种小麂的适 宜生境主要分布于核心区的中部,距离高铁的远近是影响小麂 生境适宜性的主要因素,且高铁对小麂生境的最大影响距离约 为1 500m。根据野生动物生境区因高铁建设而受到干扰的情 况,通过增加水源点、营造适宜动物生存的植被空间等措施促 进其受损生境修复。研究结果可为高铁沿线受损生境的空间识 别和修复提供参考。     

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。     

Dissolved silicate retention and transport in cascade reservoirs in Karst area, Southwest China

Presently, the fluvial fluxes of Dissolved silicate (DSi) by many famous rivers in the world have been reported significantly decreased in the past several decades. DSi retention by river damming hence becomes a great concern. In this study, the impact on DSi retention and transport by cascade reservoirs in the Karst area were investigated. Based on the monitoring data for four seasons, budget of DSi in these reservoirs were calculated. Results showed that, only the downstream eutrophic Wujiangdu reservoir (WJD) was the sink for DSi, with a value of ca. 3.5 kT DSi trapped annually. The new Hongjiadu reservoir (HJD) in the headwater area revealed to be an important source for DSi. Both Dongfeng (DF) and Suofengyin (SFY) reservoirs also released more DSi to the downstream than entering them. The great discrepancy of DSi source and sink effects among these reservoirs indicates that, (i) DSi was obviously taken up in summer and spring, and the concentration of DSi could be dropped down to below 30 μΜ; (ii) during the period of thermal stratification, the concentration stratification of DSi is also developed along the water column. Possibly DSi releasing from inundation soil and bottom sediment was the important compensation for the silicon depletion in the epilimnion. In the newly constructed reservoirs (e.g. HJD and SFY), the releasing flux of DSi can significantly exceed the assimilating flux by diatom; and (iii) due to the hypolimnion introducing for hydropower operation, water leaving the dam generally had high DSi content, and then masked the DSi taking up in the epilimnion. This process also decreased the ratio of DIN to DSi, mitigating the silicon limiting situation in the downstream.     

Herbicide accumulation and evolution in reservoir sediments

The aim of the present study was to understand the effect of reservoir configurations on sediment pesticide fate. Two dams were selected on the River Garonne, in southwest France: Carbonne and Golfech, both with reservoirs subject to accumulation of herbicide-contaminated sediment. They are situated upstream and downstream respectively of an agricultural and urban area: the Mid-Garonne. The results presented include pesticide concentrations and C/N ratios in the smaller sediment particles (< 2 mm) and values of oxygenation and herbicide concentrations in the water.The dynamic behaviour of sediment in the reservoirs is discussed. The present study shows that the theoretical lifespan (weak remanence in vitro) and the results actually observed in the sediment are conflicting. Pesticide contamination in Carbonne indicates conservation, even accumulation, of herbicide molecules while in Golfech transformation processes clearly dominate. The hydromorphological position of Golfech reservoir, i.e. located at the junction of two rivers with contrasting hydrological regimes and very different oxygenation conditions, leads to accelerated pesticide desorption or degradation. Unfortunately, this configuration is rare.     

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.     

Eutrophication downstream from small reservoirs in mountain rivers of Central Spain

In this research we examined the hypothesis that upper reaches of rivers and streams can experience eutrophication as a consequence of deep releases from dams. Field studies were conducted in four mountain rivers (Tormes, Riaza, Eresma and Miraflores Rivers) of Central Spain. The watersheds of these rivers are underlain by siliceous rocks. A small deep-release storage reservoir is found in the upper reaches of each river. Two sampling sites, upstream and downstream from the reservoir, were established in stony riffles of each impounded river. Significant (P < 0.01) increases in conductivity and nutrient (NO3-N, NH4-N, PO4-P) concentrations downstream from the reservoirs were measured. Significant (P < 0.01) increases in periphyton chlorophyll a and ash-free dry biomass were also quantified at downstream sites. Significant (P < 0.01) correlation coefficients indicated that phosphate would play a more important role as the limiting nutrient for periphyton. Relative abundances of macroinvertebrate scrapers and collector-gatherers increased downstream from the reservoirs. Furthermore, taxon dominance, total density and total biomass of macroinvertebrates tended to be higher at downstream sites than at upstream sites. In contrast, taxon diversity and relative abundance of macroinvertebrate shredders decreased downstream from the reservoirs. It is concluded that small deep-release storage reservoirs, located in upper reaches of siliceous rivers, can act as nutrient sources, causing eutrophication downstream. Nutrients would ultimately come from land/forest runoff. The fact that terrestrial vegetation was not completely removed before filling reservoirs could also contribute to the eutrophication process.     

The British river of the future: How climate change and human activity might affect two contrasting river ecosystems in England

The possible effects of changing climate on a southern and a north-eastern English river (the Thames and the Yorkshire Ouse, respectively) were examined in relation to water and ecological quality throughout the food web. The CLASSIC hydrological model, driven by output from the Hadley Centre climate model (HadCM3), based on IPCC low and high CO₂ emission scenarios for 2080 were used as the basis for the analysis. Compared to current conditions, the CLASSIC model predicted lower flows for both rivers, in all seasons except winter. Such an outcome would lead to longer residence times (by up to a month in the Thames), with nutrient, organic and biological contaminant concentrations elevated by 70-100% pro-rata, assuming sewage treatment effectiveness remains unchanged. Greater opportunities for phytoplankton growth will arise, and this may be significant in the Thames. Warmer winters and milder springs will favour riverine birds and increase the recruitment of many coarse fish species. However, warm, slow-flowing, shallower water would increase the incidence of fish diseases. These changing conditions would make southern UK rivers in general a less favourable habitat for some species of fish, such as the Atlantic salmon (Salmo salar). Accidental or deliberate, introductions of alien macrophytes and fish may change the range of species in the rivers. In some areas, it is possible that a concurrence of different pressures may give rise to the temporary loss of ecosystem services, such as providing acceptable quality water for humans and industry. An increasing demand for water in southern England due to an expanding population, a possibly reduced flow due to climate change, together with the Water Framework Directive obligation to maintain water quality, will put extreme pressure on river ecosystems, such as the Thames.     

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.     

Analysis of UK river restoration using broad‐scale data sets

This paper uses data from the UK River Restoration Centre's National River Restoration Inventory (NRRI) and the UK Environment Agency's River Habitat Survey (RHS) to analyse the relationship between restoration technique and the physical catchment context in which they have been implemented. Specifically we tested the relationship between categories of restoration technique and energy conditions, the relationship between restoration project and degree of channel modification, and whether the associations between restoration and physical catchment attributes have changed over time. Significant associations between categories of restoration technique and catchment variables were found, with direct morphological interventions needed in lower energy conditions; however, the analysis shows no change over time. This work shows that analysis of existing data sets can provide useful information to support the science and practice of river restoration and suggests that further analysis of existing ecological and geomorphological data sets provides an important learning opportunity to strengthen river restoration.     

城市绿地引鸟设计的探索与实践——浙江省长兴县龙山鹭鸟公园设计方案浅析

龙山鹭鸟公园的建设是城市绿地引鸟设计的一次探索与实践.龙山鹭鸟公园设计根据理想的鹭鸟栖息地所需的条件,提出规划对策,即营建适于鹭鸟营巢的植物群落,改造觅食区的地形和改善植物配置,加强公园的私密性建设,同时对公园的施工期和施工强度提出相应的建议.     

The use of chironomid pupal exuviae in the surveillance of sewage pollution within a drainage system

Collections of chironomid pupal exuviae were made during the summers of 1976 and 1977 above and below a number of sewage effluent discharges in the Bristol R. Avon drainage system. The effluents varied in their qualities, and discharged into rivers of different sizes.It was found that the exuvial collections showed changes in their species composition and relative species abundance which matched the overall polluting effects of the various discharges, the most change occurring below effluents of poor quality discharging into small rivers. The pollutional effects were more marked during 1976 when the rivers had unusually low flow, than in 1977 when the river flows were higher.It is concluded that biological changes consequent on sewage effluent discharge into these rivers can be monitored by sampling the chironomid pupal exuviae above and below the site of discharge.     

Stormwater impact on water quality of rivers subjected to point sources and urbanization – the case of Addis Ababa,Ethiopia

Urbanization of a catchment often causes degeneration of rivers. We studied the water quality of three rivers in Addis Ababa based on the impact of stormwater and non‐point sources, and urbanization. Along these rivers several point sources were registered, with direct discharge of industrial and domestic wastes into them. To distinguish the impact of these year‐round point‐sources from stormwater, we analysed physicochemical parameters, nutrients and heavy metals sampled from upstream to downstream sections of each river in the dry and wet season. Dissolved oxygen (DO), NO₂–N, NH₄–N, PO₄–P, (Cr(VI) and Cu) exceeded international standards, pointing to a generally poor water quality of the rivers in both seasons. NO₃–N, Mn and Zn were problematic in dry season only. Although stormwater improved DO, conductivity, PO₄–P, Cr(VI) and Zn, the levels were still critical, pointing to construction sites, agriculture and pit latrines, somewhat offsetting the effect of stormwater dilution. No clear impact of urbanization pressure was found.