Analysis of the effect of climate change on the Nakdong river stream flow using indicators of hydrological alteration

This study models the effect of climate change on runoff in southeast Korea using the TANK conceptual rainfall-runoff model. The results are assessed using the indicators of hydrological alteration (IHA) developed by U.S. Nature Conservancy. Future climate time series are obtained by scaling historical series, provided by four global climate models (GCMs, IPCC, 2007) and three greenhouse gas (GHG) emissions scenarios (IPCC, 2000), to reflect a maximum increase of 3.6 °C in the average surface air temperature and 33% in the annual precipitation. To this end, the spatio-temporal change factor method is used, which considers changes in the future mean seasonal rainfall and potential evapotranspiration as well as the daily rainfall distribution. In this study, the variance range for precipitation is from +3.55% to +33.44% compared to the present for years between 2071 and 2100. The variance range for the daily mean temperature is estimated between +1.59 °C and +3.58 °C. Although the simulation results from different GCMs and GHG emissions scenarios indicate different responses of the flows to the climate change, the majority of modeling results show that there will be more runoff in southeast Korea in the future. According to the analysis results, the predicted impacts of hydrological alteration caused by climate change on the aquatic ecosystem are as follows: 1) an increase in the availability of aquatic ecosystem habitats in Nakdong River in future summers and winters, 2) an increase in stress on the aquatic ecosystem due to extremely high stream flow, 3) an increase in the stress duration of flood events for the Nakdong River downstream and 4) an increase in aquatic ecosystem stress caused by rapid increases or decreases in stream flow.     

Multiple lines of evidence for the beneficial effects of environmental flows in two lowland rivers in Victoria,Australia

The aim of this study was to identify whether environmental flows released into two lowland rivers (the Glenelg and Wimmera Rivers, western Victoria, Australia) during the spring to autumn period had successfully ameliorated the negative effects of multiple human impacts. Macroinvertebrates and a range of physico‐chemical variables were sampled from three reaches in each river. Both rivers were sampled during three environmental release seasons with average‐sized releases (1997–1998, 1998–1999 and 2001–2002) and two drought seasons with limited releases (1999–2000 and 2000–2001). The effects of releasing average‐sized environmental flows on macroinvertebrates and physico‐chemical variables were assessed by comparison with data from the two drought seasons. For the Glenelg River, data from a reference season prior to the release of environmental flows (1995–1996) was also compared to data from the five environmental flow seasons. Multivariate analyses revealed four pieces of evidence indicating that the release of environmental flows effectively slowed the process of environmental degradation in the Glenelg River but not in the Wimmera River: (1) the magnitude of the river discharge was dependent on the size of environmental flow releases; (2) in the Wimmera River, water quality deteriorated markedly during the two drought seasons and correlated strongly with macroinvertebrate assemblage structure, but this was not observed in the Glenelg River; (3) the taxonomic composition of the macroinvertebrate assemblages among contrasting flow release seasons reflected the severe deterioration in water quality of the Wimmera River; (4) despite two drought seasons with minimal environmental flow releases, the macroinvertebrate assemblage in the Glenelg River did not differ from the average‐release seasons, nor did it return to a pre‐environmental flows condition. Therefore, it appears that environmental flow releases did sustain the macroinvertebrate assemblage and maintain reasonable water quality in the Glenelg River. However, in the Wimmera River, release volumes were too small to maintain low salinities and were associated with marked changes in the macroinvertebrate assemblage. Therefore, there are multiple lines of evidence that environmental flow releases of sufficient magnitude may slow the process of degradation in a regulated lowland river. Copyright © 2007 John Wiley & Sons, Ltd.     

湟水干流西宁段河流健康评价模型

为识别河流健康状况和揭示河流受损成因,基于河长制工作任务构建了五方面29项指标的河流健康评价指标体系,确定了评价指标的赋分标准与权重,提出了河流健康评价模型,将其应用于湟水西宁段河流健康评价工作。结果表明,准则层指标水资源保护60分,水环境治理65分,水生态修复54分,水污染防治35分,水域岸线管理63分,评价区域河流健康综合得分56分,评价等级为Ⅲ级,属亚健康水平,达到黄色预警。河长应在一定程度上组织对该段河流进行保护、修复、治理和管控。     

Trends in low flows of German rivers since 1950: Comparability of different low‐flow indicators and their spatial patterns

Climate change, land‐use shifts, reservoir storage, and water withdrawals impact low flows in rivers, creating challenges for ecological integrity and human uses. A systematic investigation of river discharges was carried out for 79 stream gauges in Germany. Available time series between 1950 and 2013 were analysed for trends in annual minimum low flows, discharge deficits, and low‐flow durations. The application of different low‐flow indicators led to similar spatial patterns, although each metric is used for different purposes in water management applications. Statistical tests identified significant discharge trends at more than half of the stations investigated. Low‐flow trends since 1950 tended to be catchment specific, suggesting that climate change has not been the dominant driver. Most of the gauges investigated showed statistically significant increases in low flows. This can be mainly attributed to reservoir management. For rivers showing snow‐ and icemelt‐dominated flow regimes, such trends are probably overlain by climate‐driven changes (increasing amounts of rainfall, earlier snowmelt in spring). In contrast, stations showing statistically significant decreases in low flows were correlated with areas of decreasing mining activity. Hydrologic impacts of climate change are widespread and significant, but the results here suggest that human river management remains the dominant hydrologic driver on many rivers.     

The influence of riparian shade on lowland stream water temperatures in southern England and their viability for brown trout

Suitable thermal conditions in streams are necessary for fish and predictions of future climate changes infer that water temperatures may regularly exceed tolerable ranges for key species. Riparian woodland is considered as a possible management tool for moderating future thermal conditions in streams for the benefit of fish communities. The spatial and temporal variation of stream water temperature was therefore investigated over 3 years in lowland rivers in the New Forest (southern England) to establish the suitability of the thermal regime for fish in relation to riparian shade in a warm water system. Riparian shade was found to have a marked influence on stream water temperature, particularly in terms of moderating diel temperature variation and limiting the number of days per year that maximum temperatures exceeded published thermal thresholds for brown trout. Expansion of riparian woodland offers potential to prevent water temperature exceeding incipient lethal limits for brown trout and other fish species. A relatively low level of shade (20–40%) was found to be effective in keeping summer temperatures below the incipient lethal limit for brown trout, but ca. 80% shade generally prevented water temperatures exceeding the range reported for optimum growth of brown trout. Higher levels of shade are likely to be necessary to protect temperature‐sensitive species from climate warming. © Crown copyright 2010.     

关于维持山西河流健康生命的理念与方法的探讨

河流是水资源的重要载体,有限的河川径流是人类生存和发展的生命之源,维持河流健康生命越来越受到社会的关注和重视。山西是全国的能源重化工基地,超重型的工业结构,高强度的水资源开发,脆弱的河流生态环境,给山西河流生命健康带来了一系列问题,造成河川径流量严重衰减,河流水质进一步恶化,水源涵养功能急剧下降,河网调蓄容量进一步减少。本文就此从水环境保护和生态环境修复的角度,提出了实施"生态治河"工程的几点设想。     

Heavy metals in the midstream of the Ganges River: spatio-temporal trends in a seasonally dry tropical region (India)

Midstream concentrations of Cd, Cr, Cu, Fe, Ni, Pb, Mn and Zn were studied at eight sampling sites in the Ganges River at Varanasi from March 2011 to February 2013. Concentrations were lowest at Site 1 (upstream of the urban core), increased consistently downstream, and were highest at Site 8 (downstream of the urban core). The rank of concentration was Zn > Fe > Pb > Mn > Cu > Ni > Cr > Cd. Except for Zn, concentrations were highest in winter. Cr, Cu, Ni, Mn and Zn did not exceed their internationally recommended maximum admissible concentration (MAC). However, over 80% of the water samples contained Cd, over 70% Pb and about 50% Fe above their respective MACs of 3.0, 10.0 and 300 µg L^?1. Since the river water is used for irrigation and drinking purposes, the study has relevance from a human health perspective.     

Modelling the effects of artificial mixing and copper sulphate dosing on phytoplankton in an Australian reservoir

An artificially destratified reservoir was simulated with the freshwater phytoplankton model PROTECH (Phytoplankton Responses To Environmental Change). The chosen site for validation was a highly managed drinking water supply reservoir (Myponga Reservoir, South Australia). Chemical dosing using copper sulphate (CuSO₄) and artificial mixing via an aerator and two raft‐mounted mechanical surface mixers (hereafter referred to as surface mixers) are used at Myponga to manage water quality, in particular the threat of cyanobacteria growth. The phytoplankton community was adequately modelled and showed that the community was dominated by species tolerant of low light doses (R‐type strategists). The light limitation in the water body was found to be the controlling factor on phytoplankton succession. Subsequently, small fast‐growing species and larger motile phytoplankton (C and CS‐type, respectively) do not have the opportunity to dominate under all simulated conditions, diminishing the need for CuSO₄ dosing. These simulations demonstrated that the individual and combined impact of the management strategies reduces the total algal biomass, but have minimal effect upon phytoplankton functional‐type succession, and R‐type species continued to dominate under all simulated scenarios. It was concluded that, due to the light‐limitation and current nutrient availability in Myponga Reservoir, the probability of persistent populations of undesirable scum‐forming cyanobacteria is minimal, even in the absence of artificial control.     

A geomorphic monitoring and adaptive assessment framework to assess the effect of lowland floodplain river restoration on channel–floodplain sediment continuity

The state of the science of lowland river floodplain restoration reflects the relatively new and experimental nature of large river floodplain rehabilitation efforts. Based on results of a case study of floodplain restoration at the lowland Cosumnes River, California, we present a geomorphic monitoring and adaptive assessment framework that addresses the need to inform and utilize scientific knowledge in lowland floodplain river restoration activities. Highlighting hydrogeomorphic processes that lead to habitat creation, we identify a discharge threshold for connectivity and sediment transfer from the channel to the floodplain and integrate discharge magnitude and duration to quantify a threshold to aid determination of when geomorphic monitoring is warranted. Using floodplain sand deposition volume in splay complexes as one indicator of dynamic floodplain habitat, we develop a model to aid prediction of the sand deposition volume as an assessment tool to use to analyze future monitoring data. Because geomorphic processes that form the physical structure of a habitat are dynamic, and because the most successful restoration projects accommodate this fundamental characteristic of ecosystems, monitoring designs must both identify trends and be adapted iteratively so that relevant features continue to be measured. Thus, in this paper, adaptive assessment is defined as the modification of monitoring and analysis methods as a dynamic system evolves following restoration activities. The adaptive monitoring and assessment methods proposed facilitate long‐term measurements of channel–floodplain sediment transfer, and changes in sediment storage and morphology unique to lowland river–floodplain interactions and the habitat that these physical processes support. The adaptive assessment framework should be integrated with biological and chemical elements of an interdisciplinary ecosystem monitoring program to answer research hypotheses and to advance restoration science in lowland floodplain river systems. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of sampling method on diatom composition for use in monitoring and assessing large river condition

Multiple diatom sampling methods exist for the assessment of lotic systems but few comparisons of their application efficacies in monitoring have been conducted. In this study 60 sites were sampled on four large, non‐wadeable rivers in Ohio and Kentucky, USA, which varied in depth, flow rate, surrounding land use and hydrologic modification. Four algae sampling methods were tested: three methods U.S. Environmental Protection Agency (U.S. EPA) Environmental Monitoring and Assessment Program (EMAP), U.S. Geological Survey (USGS QUAL and USGS QUAN) collected algae from rocks, debris and sediment in the littoral zone along a 1–2 km reach, while one method (USGS PHYTO) consisted of three cross‐river phytoplankton grab samples collected from a boat. Physical and chemical data were also collected. Little difference in diatom assemblage composition was found among the EMAP, QUAL and QUAN methods. Although compositionally similar, the PHYTO method collected a substantial proportion of relatively unique diatoms compared to the littoral zone methods. Two disturbance gradients were calculated, one based on 1 km upstream land use within a 500 m buffer, and the other based on principal component analysis dimension reduction of measured water parameters (PCAWQ). Metrics, generally indicators of eutrophication, were calculated for each sampling method and correlated with the disturbance gradients. After Bonferroni corrections, the EMAP method had six metrics correlated with the PCAWQ, while the PHYTO and QUAL methods each had four correlated metrics. Two QUAN metrics were correlated with the PCAWQ. Few metrics were correlated with the land use measure of disturbance. While the EMAP method had the most correlated metrics, this method, along with QUAL and QUAN methods are time and labour intensive (>1 h), relative to the phytoplankton method (<20 min). Resource managers may desire to weigh the benefits of two additional metrics with the EMAP method versus the costs associated with increased sampling time and effort. Published in 2007 by John Wiley & Sons, Ltd.     

塔里木河“二源一干”生态供水潜力研究

为解决塔里木河干流水资源短缺、流域损失水量过大、用水效率低下、农业灌溉用水挤占生态用水等问题,基于“节水优先”的治水方针,以塔里木河二源流(阿克苏河、叶尔羌河)及其干流(“二源一干”)的山区水库群和平原水库群为研究对象,兼顾塔里木河干流的农业灌溉用水、生态用水、工业用水、生活用水等多目标,构建并求解了现状水平年和远景规划年的山区与平原水库群联合调度优化模型,分析了塔里木河干流的生态供水潜力和山区水库群联合调度的贡献。结果表明：仅通过干流平原水库群联合调度,农业灌溉用水和生态用水的供水保证率难以满足设计要求;通过山区与平原水库群优化调度,在远景规划年各行业均满足设计保证率要求,体现了山区水库群显著的调控性能和“节水优先”治水方针的合理性和可靠性;远景规划年塔里木河干流的生态供水潜力为2.84亿m³,可为塔里木河下游生态保护与修复提供了坚实的水量基础。     

河床床面冲淤变化对渗渠产水量的影响

渗渠取水是一种传统的取水方式,其产水量会随着时间的推移而逐渐减少。影响渗渠产水量的因素是多方面的,河床床面冲淤变化对渗渠产水量的影响尤为突出。本文比较清水、浑水试验时的渗渠产水量,说明河床床面冲淤变化对渗渠产水量的影响,提出设计渗渠时应尽量将渗渠布置在水力条件良好的河段。本项研究成果可供实际工程参考。     

黄河下游游荡性河段河道整治工程环境影响评价

随着游荡性河段的进一步治理，河段的防洪压力有所下降，然而河道整治工程带来的负面影响也逐渐表现出来。今后在河道整治的同时，尽可能消除工程可能带来的负面影响，考虑河道的输沙要求应该成为河道整治必须考虑的重要因素。同时，非工程措施也应该成为今后河道整治的重要补充手段。     

关于长江中下游干流河道采砂管理决策的思考

运用公共管理决策的理论分析了决策在长江中下游干流河道采砂管理中所发挥的作用,并就决策中领导因素、决策程序、利益驱动和风俗习惯等方面因素所起到的影响作了进一步阐述.长江中下游干流河道采砂管理的发展历程,也就是国家及各级政府有关河道采砂问题决策不断更新、调整的一个过程.长江中下游干流河道采砂管理的好坏,关键就在于国家的有关决策是否科学、合理,各级人民政府的政策择取是否正确.     

基于河流健康理念的河流管理发展过程浅析

对国外河流管理的历程、现状和趋势进行了分析,讨论了我国河流管理的发展历程,并对七大流域目前的河流管理中存在的问题进行了归纳。在此基础上,结合河流健康理念,从综合考虑河流管理中的行政手段和技术方法、注重河流综合管理工作中的公众参与、建立恰当的河流健康评估体系并与河流综合管理的集成、尝试河流动态管理方法和建立河流数字化信息系统等5方面提出了我国未来基于流域的河流管理的发展建议。     

Multi‐scale modelling of land‐use change and river training effects on floods in the Rhine basin

Land‐use changes effects on floods are investigated by a multi‐scale modelling study, where runoff generation in catchments of different sizes, different land uses and morphological characteristics are simulated in a nested manner. The macro‐scale covers the Rhine basin (excluding the alpine part), the upper meso‐scale covers various tributaries of the Rhine and three lower meso‐scale study areas (100–500 km²) represent different characteristic land‐use patterns. The main innovation is the combination of models at different scales and at different levels of process representation in order to account for the complexity of land‐use change impacts for a large river basin. The results showed that the influence of land‐use on storm runoff generation is stronger for convective storm events with high precipitation intensities than for long advective storms with low intensities. The simulated flood increase at the lower meso‐scale for a scenario of rather strong urbanization is in the order of 0 and 4% for advective rainfall events, and 10–30% for convective rain storms with a return period of 2–10 years. Convective storm events, however, are of hardly any relevance for the formation of floods in the large river basins of Central Europe, because the extent of convective rainstorms is restricted to local occurrence. Due to the dominance of advective precipitation for macro‐scale flooding, limited water retention capacity of antecedent wet soils and superposition of flood waves from different tributaries, the land‐use change effects at the macro‐scale are even smaller, for example at Cologne (catchment area 100 000 km²), land‐use change effects may result in not more than 1–5 cm water level of the Rhine. Water retention measures in polders along the Upper and Lower Rhine yield flood peak attenuation along the Rhine all the way down to the Dutch border between 1 and 15 cm. Copyright © 2007 John Wiley & Sons, Ltd.     

A geomorphic perspective on the rights of the river in Aotearoa New Zealand

The granting of rights to the Whanganui River in 2017 emerged as an outcome of Tribunal hearings relating to breaches of the Treaty of Waitangi, signed between Māori chiefs and the British Crown in 1840. As this expression of a river as having legal personhood with rights reflects a distinctively Māori perspective upon river systems, it offers the prospect for a new era of sociocultural approaches to river management in Aotearoa New Zealand. Using the Whanganui River as a case study, this paper explores prospective geomorphic meanings of river rights. The paper asks, “What role can geomorphology play in identifying, articulating and protecting the rights of a river?” Ancestral Māori relations to the river based upon mutual codependence (reciprocity) are juxtaposed against geomorphic understandings of a river's agency as expressed through self‐adjustment, diversity of form, evolution, and catchment‐scale connectivities. Relations between river science and indigenous concepts of rivers, framed under the auspices of river rights, present opportunities for different approaches to river management.     

黑河额济纳旗天然林草植被保护评价指标研究

针对黑河下游额济纳旗天然林草植被面积不断减少、生态环境日趋恶化的问题；根据已采取的保护措施和已经退化的典型天然林草植被的实地对比调查结果，结合已有研究成果，在对天然林草植被保护评价主要因素地下水埋深、植被覆盖度、植物种类、土地沙化程度等分析的基础上，采用定性和定量相结合的方法，提出了额济纳旗天然林草植被的保护评价指标。     

大型底栖无脊椎动物在河流健康评价中的发展趋势

现从河流健康的内涵出发,回顾河流健康评价指标的发展历史,通过分析单一生物指数、生物多样性指数以及生物完整性指数的研究进展,评述了大型底栖无脊椎动物作为生物监测工具在河流健康评价之中的重要作用。针对其存在的问题,从技术、方法等方面提出建议,并展望大型底栖无脊椎动物在河流健康评价中的发展趋势,力求为我国河流健康评价工作提供借鉴,以便能够更好的进行流域管理和生态修复。     

湟水干流西宁～民和段河道生态基流量研究

湟水是青海省地表水利用率最高的河流,湟水干流西宁~民和段也是青海省水污染最严重的河段之一。本文以乐都水文站和民和水文站断面为控制节点,利用实测水文资料,通过历史水文资料法,初步确定西宁~民和段河段生态基流量为4.55 m3/s。这将为湟水中下游水资源可持续利用的管理目标提供了现实途径,具有现实意义。