Environmental issues of the three gorges project,China

This paper reviews several issues relating to the potential environmental impacts of a planned high dam at Three Gorges on the main course of the Changjiang (Yangtze River).     

A review of the effect of river regulation on mayflies (Ephemeroptera)

Impoundment and diversion of watercourses for power production and water supply can have profound effects on the mayfly fauna. To explain such effects a species-specific approach is adopted on account of differing habitat requirements and life histories in the order and even within genera. Environmental conditions such as discharge and flow patterns, temperature, food availability, and predation may be changed. This leads to changes in the density and species composition of the mayfly community, especially when there is a hypolimnion drain from reservoirs. Temperature changes below such reservoirs may remove obligatory life cycle thresholds. Prolonged periods of low discharge lead to the dominance of genera, such as Paraleptophlebia, Choroterpes, Siphlonurus, and Pseudocloen, typical of slow-flowing and lentic habitats. The life cycle plasticity and opportunism shown by Baetis rhodani in Europe and B. tricaudatus in North America have undoubtedly contributed to their success in regulated rivers. The life history characteristics of Tricorythodes are also advantageous below dams. The increased growth of periphyton and mosses below many dams favour certain Ephemerellidae, but restrict or eliminate many Heptageniidae. In order to survive adverse conditions, flexible life cycles or a short period of rapid nymphal growth coupled with a long period of egg development, are advantageous.     

River regulation and nature conservation

The basic tenet of nature conservation is the protection and management of the environment so as to maintain its wildlife. Much of the effort is presently expended in securing the continued existence of rare, endangered or threatened species, communities, and habitats. River regulation involves considerable environmental manipulation. This extends beyond the modification of discharge regimes through the need for ancilliary operations, including the construction of dams, channel modification and transfer of water between catchments. The imposition of regulation modifies the natural environment in which the original communities of organisms became established. Where the ecological requirements of these organisms are destroyed or modified beyond the limits of their adaptations or tolerances they are unable to survive. The communities are thus changed and replaced by others, perhaps of lesser conservation value. Since the aims of nature conservation and river regulation are intrinsically incompatible the best that can be hoped for is that regulation schemes are designed, constructed, and operated so as to ameliorate environmental damage.     

Assessing options for stream regulation using hydrologic simulations and cumulative impact analysis: Flathead River Basin,U.S.A.

This study attempted to resolve regulation problems up- and downstream of Flathead Lake and on the lake proper. Members of a technical working group, representing eight water and wildlife management agencies, contributed 75 regulation scenarios they deemed necessary to conserve or enhance ecological (fish and wildlife) and societal (hydropower production, flood control, and recreation) resources for which they had management authority. The hydrology model simulated the effect of each scenario on system water balance; scenarios that were within the physical and legal constraints of the system were accepted for determination of cumulative impacts on resources. A multiattribute tradeoff analysis was used to assess cumulative impacts to key resources as a consequence of each regulation scenario (simulation) accepted for evaluation. Impacts were subjectively and independently quantified by each member of the working group following a point and importance weighting system agreed to a priori. Valuation of impacts was done on the basis of 36 technical studies of the effects of regulation on system resources. Impact valuations were summed to yield a variable referred to as weighted cumulative impact (WCI), where the highest, positive WCI indicated least cumulative impact on resources. Scenarios were then ranked in terms of WCI. When ecological resources only were evaluated, the preregulation Flathead Lake scenario generated the highest WCI. However, when all resources were considered, scenarios ranked very differently but a preferred alternative was identified by virtue of its highest WCI. This interactive process of hydrology simulation and computation of cumulative impacts mediated resource conflicts and served as an important tool in deriving water management recommendations in the Flathead River Basin. The process may be useful elsewhere.     

Outstanding problems in river regulation

Integrated river basin management has been the backcloth against which river regulation has been practiced in England and Wales for the past 14 years. Its success is reviewed and the forthcoming changes in legislation are critically examined. A number of problems facing the emergent National Rivers Authority are discussed. The need for co-operation rather than conflict is advocated wherever environment is to be protected and when competing pressures impact on river resources. A number of technical issues remain unresolved and the need for continuing work is recognized.     

漕河渡槽槽身混凝土防裂研究

分析了南水北调中线干线工程漕河渡槽在工程施工初期槽身产生裂缝的原因,产生裂缝的原因为：混凝土内外温差大;混凝土自身结构约束及自重应力大;施工过程中混凝土养护不到位等。通过优化混凝土配合比、选用高效减水剂、优化骨料级配等技术手段控制渡槽槽身混凝土裂缝的产生。     

Stream regulation in Argentina,including the superior Paraná and Paraguay rivers

Argentine water resources are located in three hydrologically contrasting regions: the so-called Del Plata basin, the Arid Central Andean area, and Patagonia. About 150 dams and impounding reservoirs that exceed a capacity of 150 × 103 m³, have been built. Most limnological studies of regulated rivers have been conducted recently. In the Del Plata basin, Argentine dams are scarce, although many have been built or are projected upstream, mainly in Brazil. The ecological problems of the reservoirs are related to decomposition of inundated terrestrial vegetation; algae blooms, dissolved oxygen depletion phenomena, eutrophication, impaired fish migrations, overproduction of water hyacinth Eichhornia spp., and schistosomiasis. The importance of examining the influence of the projected middle Paraná dams on downstream sediment regimes, especially as it affects the delta, is emphasized. In the Arid or Central Andean region, the main development of the Grande-Tercero rivers includes dams, reservoirs, and the operation of a nuclear power plant. One of the most important effects will be a slight increase in the water temperature of the Rio Tercero reservoir as a consequence of water use in the cooling system of the nuclear power plant. In the Patagonian region, the main dams are those built and projected for the Colorado and Negro basins. In the Negro basin studies are being carried out mainly in the Ramos Mexia Reservoir, on different aspects of zooplankton and phytoplankton, benthos, and fishes. Commercial fishing is not permitted and fishing is based mainly on the introduced salmonids which show symptoms of undernourishment because of a lack of forage fishes. Indigenous fishes have been decimated by the introduced salmonids. Although studies have been conducted in several areas, much work remains to be done in relation to the environmental effects of dams on streams in Argentina. Results from ecological studies are still insufficient to solve the multiple problems associated with them, such as climatic influences, retention of suspended solids, deforestation, schistosomiasis and other aquatic diseases, pollution, eutrophication, fish-ways and fish migrations, accumulations of the water-hyacinth, salt and nutrient regimes, and siltation. Even partial solutions to these problems will require an ensemble of urgent measures to assure the maximum benefits with minor risks and ecological costs.     

When the river does not naturally flow: a case study of unsustainable management in the Tagus River (Spain)

ABSTRACT

This article assesses the main problems facing the Spanish Tagus River basin, and the management that has caused (or allowed) them. It examines the economic, social, environmental and political-institutional dimensions of Tagus River management in terms of sustainable development. We find that the institutions responsible for designing and implementing water policy in the Tagus basin have been unsuccessful in balancing the three classic dimensions of sustainability, resulting in systematic and recurrent failure to comply with the European Water Framework Directive and the principles of sustainable development.     

黄河水权体系探讨

黄河水权体系框架由水权种类设定、水权管理、水权转让以及相应的辅助体系构成。从维持黄河健康生命角度,提出建立黄河河流生命水权概念;从用水安全与差别费率的角度,建立了差别保证率水权概念。论述了取水许可与有偿使用、总量控制与定额管理、流域管理与区域管理、市场配置与统一调度4种水权管理方法与原则。从促进水权转让的角度,建立了初始水权与受让水权的概念,提出了建立水权转让折算体系与审批体系以及相应的水价格体系。列举了黄河水权体系的辅助体系。     

汾河三坝灌区咸淡水分布研究

本文用实测资料和电测资料，研究出该区域的咸淡水分布，对指导冲积平原地区打井，合理开发利用地下水资源有一定的指导意义。     

引洮工程中地表水地下水资源的联合调度与利用

定西内官一香泉盆地具备良好的地下水赋存条件,多年来一直为城区生活、工业及当地农业发展提供水源,但随着当地各方面用水需求的增加,盆地地下水开采量逐年上升,导致采补失衡,地下水位下降严重．旨在改善甘肃中部定西一带极度缺水现状的引洮供水工程即将开工建设,结合盆地地形、地理、地质条件,综合研究工程外调地表水与当地盆地地下水的联合调度运行管理具有重要意义．文中结合引洮工程规划,进行了联合利用的初步分析．     

The impact of river regulation on invertebrate communities in the U.K.

The impact of river regulation on invertebrates has received comparatively little attention in the U.K., with most studies concentrating on the effects of impoundment. During dam construction invertebrate diversity and abundance decreases. Longer term alterations in community structure (which usually extend for a relatively short distance downstream) reflect changes in flow, substrate, temperature, and water quality. In particular adverse effects on invertebrates have been attributed to a reduction in substrate heterogeneity together with an accumulation of sediment. Responses to impoundment within and between taxonomic groups are highly variable. In general Ephemeroptera and Coleoptera are reduced. Of the Plecoptera the Perlodidae and Chloroperlidae are more likely to be adversely affected than the Nemouridae or Leuctridae. The impact of impoundment on net-spinning Trichoptera varies with reductions in some populations and enhancement in others. Simuliids are usually restricted, probably because of a lack of suitable oviposition or attachment sites. Freshets released from reservoirs increase the level of invertebrate drift. However, the full consequences of impoundment on drift, recolonization, and upstream migration have yet to be assessed. There is some evidence that modified temperature regimes cause extended egg hatching periods and alter larval growth rates but further studies are needed. Little is known of the effects of inter-river transfers on invertebrates, but it has been suggested that changes in flow velocity, water chemistry, suspended solids, and temperature together with translocation of organisms are all likely to be important. The limited information available for groundwater schemes indicates that they are not detrimental to invertebrates. Their impact, however, is dependent upon factors such as the extent and timing of flow augmentation. It is suggested that there is scope for positive management of invertebrate communities through river regulation, although at present attitudes and practices do not encourage this. Many gaps in our knowledge still remain and these are discussed in relation to future research needs.     

Innovations in Water Management

Abstract

The water allocations made to the lower Colorado River Basin under the 1922 Colorado River Compact. as well as the later contractual allocations made by the Secretary of the Interior under the Boulder Canyon Project Act to the States of Arizona, California, and Nevada, and water agencies in those states, were based on significant overestimates offuture water supply. Based on the priority system in each state, the burden of the current shortages has fallen principally on municipal water users. This paper reviews the steps they have taken through innovative conservation measures, water transfers and water banking to deal with the shortage situation. It also briefly discusses the status of native-American rights in the lower Colorado River Basin in such efforts and the possibility of fixed term leases of water from Upper Basin States or users to Lower Basin municipal users.     

中国水利的发展方向

黄河下游发生断流的自然因素是降雨偏少、径流量偏枯，决定性因素是黄河流域用水量急剧增加，而直接原因是缺乏有效的管理。黄河上中游的治理造成下游主河槽萎缩，一旦上游发生暴雨，洪水漫流造成灾害。为了保证黄河水资源的可持续利用，必须强调在黄河流域和下游两岸建立节水型的社会并严格保护水源，防止污染。长江中游防洪工作中的重要矛盾是由于人口增长带来土地的过度开发，从而造成围湖和蓄洪的矛盾。今后应根据可持续发展的要求，将水利工作纳入我国人口、资源、环境的巨系统中，修订水利规划，提高用水效率，保护水源和生态环境，完善工程和非工程措施，组织多部门、多学科的协作攻关。     

漫湾水库水温水质的回顾评价

根据漫湾水电站环境监测站资料，对水库蓄水前后水环境中水温、水质因子的变化进行初步分析，认为下泄水量的水温与天然状态比较变化不大，对环境影响很小，而水质则较天然状况稍差。库区上游江流域兰坪铅锌矿是库区水质重金属污染来源，黑惠江则可能是库区有机污染的主要来源。     

Lake Turkana,major Omo River developments,associated hydrological cycle change and consequent lake physical and ecological change

This study aimed to explore Lake Turkana's ecological reliance on hydrology and to determine the hydrological changes and consequences arising from the major hydropower and irrigation developments in the lake's basin. The major developments on Ethiopia's Omo River are especially significant as this river provides over 80% of the lake's annual freshwater influx and associated nutrients. The cascade of hydropower dams permanently dampens the natural hydrological cycles and lake level variability. The driving force of the flood influx to the lake is curtailed and the pattern of lake currents will adjust. Ultimately 80% of the river inflow to the lake will be regulated. Large volumes of water are required to initially fill the hydropower dam reservoirs. During 2015–16 when the huge Gibe III reservoir was filled, Lake Turkana's water level declined 2?m.The study has shown that large-scale irrigation schemes in the Lower Omo can potentially abstract 50% of the Omo River water, and that this would cause the lake level to shrink permanently to the detriment of the lake ecology. Possible lake level drops of over 15?m are demonstrated. The basin's natural capital is being replaced by large-scale plantation developments. The hydrological changes are drastic and the ecological consequences on Lake Turkana have not been fully understood. Without serious mitigation measures, Lake Turkana is a potential African Aral Sea disaster in the making, emulating what has happened to other great lakes such as Lake Chad.     

Effects of transferring glacier-fed water to a clear-water mountain river on the production and food organisms of brown trout (Salmo trutta L.) in Southern Norway

The effects of transferring glacier-fed water to a clear-water river on production and food organisms of brown trout (Salmo trutta L.) were investigated in a mountain river, in southern Norway. Production in unregulated fluvial habitat was 271.5 g 100 m^?2 yr^?1 compared with 103.1 g 100 m^?2 yr^?1 in a glacier-fed reach of the river. This difference was due to low fish density and recruitment rate. The growth rate, at least for younger fish (2+ to 4+ age groups), was significantly higher in the regulated reach of the river. The main difference in food composition was the low abundance of crustaceans Eurycercus lamellatus and Gammarus lacustris in the regulated reach. Trichopterans were the main diet component in both sites.     

The downstream impacts of the burgomillodo reservoir,Spain

The Burgomillodo Dam, located in the middle Rio Duraton (north Spain, Duero Basin), has created a small eutrophic reservoir with a capacity of 15 × 10⁶ m ³ and a maximum depth of 40m. Burgomillodo Reservoir is solely used for producing hydroelectric power. The regulated flow pattern of hypolimnial waters is characterized by higher daytime flows than those by night, with low flows at weekends all the year round. The environmental impact generated by this hydropower scheme on the river downstream was assessed by comparing physiochemical characteristics and aquatic communities of an upstream site (reference station) with those of three downstream stations, which were located 0–2, 2–5, and 7–6 km below the dam. Water temperature, pH and dissolved oxygen were significantly lower downstream from the reservoir. Hardness, alkalinity, suspended inorganic matter, and conductivity had reduced annual variability below the dam. Photosynthetic activity was directly involved in the recovery of dissolved oxygen and pH values. Species richness and abundance of macrophytes increased just below the dam. Macrobenthic and fish communities were composed of higher numbers of potamic species. Number of taxa, density, biomass, and diversity were higher at the reference site, recovering their values as the distance below the reservoir increased. Macrobenthic trophic structure was changed by an increase in predators and filter feeders and a decrease in shredders. Environmental impact values for the macrobenthic community living just below the dam were higher than those for the fish community. It is concluded that the main physiochemical factors involved in environmental impacts were dissolved oxygen deficit and short-term flow fluctuations for the macrobenthic community, and oxygen deficit for the fish fauna. Benthic macroinvertebrates appear to be the best aquatic organisms for detecting changes and for reflecting the spatial recovery of environmental conditions.     

欧盟流域管理规划试点项目

丹麦的欧登塞河流域是欧洲14个流域之一,也是实施欧盟《水框架指令》流域管理规划的试点。作为共同实施战略的一部分,通过测试一系列技术指导文件,以确保形成统一的流域管理规划模式。项目成果包括3个部分,即流域特性报告、典型河流流域管理计划和用于公众咨询的简易报告。通过欧登塞河流域试点项目的实施,欧盟各成员国的水管理机构及欧盟委员会获得了流域管理的知识和经验,同时可为中国未来的流域管理规划提供有益的借鉴。     

山西省黄河流域地表水水功能区划分及其研究

水功能区划的划分是实现水资源综合开发、合理利用、积极保护、科学管理的基础工作，本文根据“全国水功能区划技术细则”，结合对山西省黄河流域的自然、社会情况，尤其是水资源状况的综合分析，系统介绍了水功能区划的方法，对我省黄河流域河流地表水进行水功能区划并提出管理建议。