Reducing reservoir impacts and improving outcomes for dam‐forced resettlement: experiences in central Vietnam

The present study focuses on the growing problem of the impacts of human displacement resulting from hydropower dam construction, within the context of the integrated lake basin management of dam reservoirs. Dam‐forced displacement and resettlement can pose severe challenges to the environmental, economic and social sustainability of a reservoir basin. A case study in Quang Nam Province, central Vietnam, suggests that many resettled communities experience impoverishment due to the lack of adequate replacement land, declines in supplemental food sources and reduced access to natural resources. In response to such situations, resettled residents may (i) destroy lake catchment forests for the purpose of converting them to farmland or engage in illegal logging; (ii) increase agrichemical inputs on reduced land, thereby polluting run‐off and groundwater; and (iii) place increased pressure on fish stocks and wildlife. Examples are provided from central Vietnam to illustrate the need for applying management approaches that allows the affected people to become beneficiaries of dam projects and for including civil society organisations in resettlement planning. The hydropower authority can fund benefit‐sharing mechanisms, including village‐level electrification and payment for environmental services schemes, in which resettled populations are paid for forest maintenance and protection to prevent erosion and deforestation, and reservoir access can be provided for fishing, aquaculture and agriculture. Civil society organizations can advocate for residents’ interests and for reallocation of protected forest land for community forestry. These approaches can be supported by an inclusive reservoir management board working to achieve environmental sustainability, economic growth and social equity.     

略谈以支流为单元的淤地坝体系建设

从1959年绥德水土保持科学试验站提出"坝系"一词以来,淤地坝建设经过试验研究、试点探索和示范推广,转入大规模建设的新阶段.继2003年黄土高原启动实施83条小流域坝系建设之后,黄委又拟于近期开展以支流为单元的淤地坝体系建设.为此,我们从发展思路、布坝密度、坝系结构、建坝顺序以及大型拦泥库、淤灌工程和坡面治理诸方面,来探讨支流坝系建设应注意解决的若干技术问题.     

Temporal changes in the hydrology and nutrient concentrations of a large tropical river: Anthropogenic influence in the Lower Grijalva River,Mexico

Dam construction and nutrient loading are among the greatest threats to freshwater ecosystems, altering ecological processes and the provisioning of ecosystem services. Temporal change in hydrology and ambient nitrogen and phosphorus concentrations was studied on the Grijalva, a large tropical river in southern Mexico, where four hydroelectric dams operate and where land conversion has impacted the freshwater environment. Temporal changes in discharge and in river chemistry were examined by analysing long‐term discharge and nutrient data using the software Indicators of Hydrologic Alteration and Mann–Kendall tests. Furthermore, additional water chemistry samples were collected to examine seasonal nutrient dynamics in the lower Grijalva. Long‐term discharge data indicated dam construction has severely altered temporal patterns in discharge and other hydrological characteristics. The lower Grijalva has also experienced increase in nitrate concentrations through time, which may be attributed to the expansion of agricultural and urban areas in the watershed. In contrast, total phosphorus appeared to decline at the sites influenced by dam construction. Lower nutrient concentrations were recorded upstream from the city of Villahermosa, suggesting that inputs from urban areas may have contributed to nutrient loading. Additionally, higher nitrate and total phosphorus concentrations were detected in tributaries draining intensive agricultural and suburban areas. Collectively, the results from the study suggest that dam construction and land conversion in large, tropical watersheds can produce chemical and hydrological changes, which may negatively impact important ecosystem services—such as fisheries and the provisioning of sources of drinking water—and may compromise the integrity of coastal zones.     

流域生态修复科学性思考

流域生态系统规划已经成为流域相关研究中的重点内容,科学的流域生态系统规划理论和方法为流域的健康和可持续发展提供了丰富的研究途径和思路。基于生态学理论,强调了非生物要素作为生物要素的基础,阐述了水文、地形、土壤等对生态修复的作用。倡导基于自然解决方案的流域生态修复,强烈主张以水文修复作为生态修复的基础,以流域水文规划为主导的多专业协同的流域生态保护及修复方法。建议生态修复首先要理解自然生态要素之间的关系,然后统筹规划流域范围内的生物和非生物要素,并协调人类生活和生态系统保护之间的关系,为流域生态系统的健康、稳定和可持续发展提供科学性解决方案。     

水电工程设计施工中的生态环境问题与对策

近年来，随着社会经济发展水平的提高和公众环保意识的增强，大坝建设对生态环境的影响受到日益严重的关注。就国家的发展而言，中国的现代化需要水电资源的开发，而另一方面，大坝建设带来的生态环境问题将可能威胁国家的可持续发展战略。如何协调水电资源开发利用与生态环境保护的关系，实现经济效益与生态保护的双赢，是未来大坝建设必须考虑的问题。本文在分析水电工程建设对生态环境影响的基础上，以土石坝工程为例，研究、探讨了水电工程设计施工中的生态环境问题及其相应的对策措施，提出了建设生态友好的水电工程的一些相关准则。     

大坝的工程生态要求

大坝在防洪、供水、灌溉和发电等方面具有重要的作用,发挥着巨大的经济社会效益。但是,大坝在建设或运行过程中,直接或间接地引发了一系列生态与环境问题。遵循人与自然和谐相处的理念,建设大坝引发的生态与环境问题日益受到关注,据此提出大坝建设和运行中的工程生态与环境的要求。     

流域系统科学初探

随着人类社会对河流乃至流域影响广度、深度和强度的不断增加,对流域系统内部不同要素之间的互馈关系和博弈关系研究的不断拓展和深入,以致流域系统治理及其战略研究已经超过传统学科的范畴,亟需建立新的学科支撑体系。本文基于近十年的探索研究,提出了流域系统科学的概念,并对其研究对象、科学内涵、科学问题、研究方法及研究前景进行了全面阐释。流域系统科学以物质、能量、信息、价值流动过程为纽带,以行洪输沙-生态环境-社会经济三大子系统组成的流域复杂巨系统为研究对象,其基础研究需求包括各子系统内部演化过程与机理、各子系统间相互作用关系与协同演化机制、流域系统协调发展策略与战略布局3个层面。流域系统科学以传统学科为基础支撑,基于系统理论和方法探索制约流域治理保护和区域社会经济高质量发展的协同博弈关系,通过全流域系统观测网络和大数据平台建设,构建流域系统治理集成研讨厅,为流域系统治理保护与管理的战略研究提供科学的理论方法体系。     

LAND USE READJUSTMENT IN THE COMPREHENSIVE WATERSHED MANAGEMENT IN CHINA

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Role of Large Dams in the Socio-economic Development of Mexico

In Mexico, 473 km 3 of water is renewed annually, of which 198.4 km 3 is abstracted by the productive sectors and for domestic purposes. Such figures, however, give a false sense of water abundance, because its spatial and temporal distribution is not homogeneous. In order to cope with this mismatch, numerous water-retaining structures have been constructed. Certainly, dams have been a key element to balance the spatial and the temporal variations in the water availability, and they have played a crucial role in the socio-economic development of Mexico. However, the benefits could be more if water management practices were more efficient, equitable and modern. This paper focuses specifically on dam development in Mexico, and it points out that, unquestionably, large dams have had direct, negative impacts. However, it should be noted that many of those negative impacts are the results of inefficient planning, inadequate expertise and improper management. Dams, like any other major infrastructures, have economic, environmental and social benefits and costs. Accordingly, the dams must be properly planned, built and managed with the best scientific and technical knowledge available. The real question for Mexico is not whether dams should be constructed or not, but rather how should the dams be planned and managed so that the economic, social and environmental benefits to the society as a whole can be maximized and the costs can be minimized.     

Watershed Management Technique to Control Sediment Yield in Agriculturally Dominated Areas

Abstract

Non-point source pollution is recognized internationally as a critical environmental problem. In Illinois, soil erosion from agricultural lands is the major source of such pollution. The erosion process, which has been accelerated by human activity, tends to reduce crop productivity and leads to subsequent problems from deposition on farmlands and in water bodies. Comprehensive watershed management, however, can be used to protect these natural resources. In this study, a discrete time optimal control methodology and computational model are developed for determining land use and management alternatives that minimize sediment yield from agriculturally-dominated watersheds. The solution methodology is based on an interface between a genetic algorithm and the U.S. Department of Agriculture's Soil and Water Assessment Tool. Model analyses are performed on a farm field basis to allow capture of different, local stakeholder perspectives, and crop management alternatives are based on a three-year rotation pattern. The decision support tool is applied to the Big Creek watershed located in the Cache River basin of Southern Illinois. The application demonstrates that the methodology is a valuable tool in advancing comprehensive watershed management. The study represents part of an ongoing research effort to develop an even more comprehensive decision support tool that uses multi-criteria evaluation to address social, economic, and hydrologic issues for integrative watershed management.     

Effects of dams in river networks on fish assemblages in non‐impoundment sections of rivers in Michigan and Wisconsin,USA

Regional assessment of cumulative impacts of dams on riverine fish assemblages provides resource managers essential information for dam operation, potential dam removal, river health assessment and overall ecosystem management. Such an assessment is challenging because characteristics of fish assemblages are not only affected by dams, but also influenced by natural variation and human‐induced modification (in addition to dams) in thermal and flow regimes, physicochemical habitats and biological assemblages. This study evaluated the impacts of dams on river fish assemblages in the non‐impoundment sections of rivers in the states of Michigan and Wisconsin using multiple fish assemblage indicators and multiple approaches to distinguish the influences of dams from those of other natural and human‐induced factors. We found that environmental factors that influence fish assemblages in addition to dams should be incorporated when evaluating regional effects of dams on fish assemblages. Without considering such co‐influential factors, the evaluation is inadequate and potentially misleading. The role of dams alone in determining fish assemblages at a regional spatial scale is relatively small (explained less than 20% of variance) compared with the other environmental factors, such as river size, flow and thermal regimes and land uses jointly. However, our results do demonstrate that downstream and upstream dams can substantially modify fish assemblages in the non‐impoundment sections of rivers. After excluding river size and land‐use influences, our results clearly demonstrate that dams have significant impacts on fish biotic‐integrity and habitat‐and‐social‐preference indicators. The influences of the upstream dams, downstream dams, distance to dams, and dam density differ among the fish indicators, which have different implications for maintaining river biotic integrity, protecting biodiversity and managing fisheries. Copyright © 2010 John Wiley & Sons, Ltd.     

小流域坝系优化规划模型及其应用

在水土保持治沟坝系规划中，采用非线性规划方法，建立了适用于新建坝系规划和已成坝系改造规划的小流域坝系优化规划模型，利用该模型可求出坝系中诸坝较优的建坝高度和适宜的建坝时间。以孙家沟流域为例，对建立的优化模型进行了验证。     

COMPARISON OF THE HYDROMORPHOLOGICAL EVOLUTION OF THE L'ASSOMPTION AND OUAREAU RIVER CHANNELS (QUEBEC,CANADA)

The monitoring station method, which is based on comparing data before and after dam construction, is commonly used to quantify the hydromorphological impacts induced by dams. However, in the absence of pre‐dam construction data, other analytical methods may be used to detect changes downstream from dams that remain more or less constant over time. The study used one such method, the control station method, to constrain changes which may be linked to construction of the Rawdon Dam, in 1913, on the Ouareau River. Thus, a comparison of the hydrological (seasonal daily maximum flows) and morphological (mean bankfull width and sinuosity) evolution of the Ouareau and L'Assomption Rivers during the period 1930 to 2008 was carried out. The surface area as well as the climatic, lithological, land use and physiographic features of the two watersheds are nearly identical in the study area. The comparison revealed three changes that may be linked to the Rawdon Dam: an increase in the magnitude of daily maximum flows downstream from the dam for all four seasons, which is inferred to have resulted in extensive widening and low sinuosity of the Ouareau river channel downstream from the Rawdon Dam relative to the L'Assomption river channel. These types of morphological changes are consistent with changes observed downstream from some dams. The Rawdon Dam had no effect on the interannual variability of daily maximum flows, which are characterized by a significant increase in mean in winter in both watersheds. This increase, which is abrupt, occurred in 1973 for both rivers. Copyright © 2012 John Wiley & Sons, Ltd.     

SMALL IS BEAUTIFUL? STATE OF THE DAMS AND MANAGEMENT IMPLICATIONS FOR THE FUTURE

Dams are a critical component of water infrastructure, providing services such as water supplies, recreational opportunities and flood control. At the same time, dams alter the flow regime of rivers and the biota that inhabit them. Large dams have been the subject of many studies because of their potentially significant impacts on stream hydrology and ecosystems. However, most dams are not large and consequently have received far less attention. Data for more than 5700 dams in New York State, USA located in 17 watersheds were used to develop watershed level metrics that relate the characteristics of the dams to the hydrology and demographics of each watershed. Metrics presented, stratified by watershed, include median structure age, density, dams per stream length, persons per dam, storage per drainage area, storage per person and percent high impact dams (high hazard and large). These metrics were used to perform a simple characterization of the 17 watersheds. Considerable regional differences in these parameters suggest varying management strategies in each watershed. A new era of river management has resulted in the removal of many dams, which is driven by the high cost of maintenance and state regulations. Copyright © 2013 John Wiley & Sons, Ltd.     

Kariba Reservoir: Experience and lessons learned

The Kariba Reservoir is a large, tropical reservoir created nearly half a century ago on the Zambezi River in Zambia and Zimbabwe. It has a complex sociopolitical history, being designed during a period when human rights, social justice and equity in relation to colonial subjects were secondary concerns, as well as a period in which environmental management was an emerging discipline. Many of the management issues that have arisen over time were not foreseen when the dam was being planned. This paper examines several of these issues, including population increase in the basin, the need for ecological manipulations to optimize ecosystem functioning, and environmental problems such as eutrophication, microbial pollution, hyacinth invasion, and issues arising from pest control. The institutional arrangements also are critiqued, with a focus on how forced relocation of indigenous communities in the course of water resource development can lead to long‐lasting, trans‐generational social traumas. It is concluded that reservoir planning must explicitly address community needs, with equity issues in the sharing of water resource development benefits being clearly considered, and that post‐project integrated watershed management efforts must be part of reservoir planning.     

Conservation and improvement of the environment in dam reservoirs

Dams in Japan have contributed a great deal to the protection of life and properties, effectively prevented damage caused by floods, supported the maintenance of the normal functions of the river flow, and improved and conserved river environments. However, in recent years, many people in Japan have raised questions about the existing dams and dam projects without correct evaluation of the past impacts of dams. It has therefore become difficult to plan new dam projects and to operate existing dams properly as intended. People opposed to dams have commonly argued that dams inflict more damage on the environment than any other structure. For the reason that a dam will submerge its natural surroundings, counter measures to minimize its effects on the environment as much as possible should be taken, through every stage of the project. Particular attention should be given at the planning stage of dam projects. The latest developments in the conservation of the environment following dam construction and the concrete measures taken by dam constructors to follow the regulations concerned in Japan are described. The mitigation of the environmental impacts of dams and the restoration of the environments of downstream rivers are now the major issues.     

Assessment of the environmental,social and economic benefits of a water transfer tunnel in the Nakdong River,Korea

This study compares the benefits and disadvantages of two options, i.e. dam construction and a water transfer tunnel between two existing dams, with a particular focus on their effects on the natural environment and local communities and their respective economic efficiencies. It is concluded that significant advantages exist for the construction of a water transfer tunnel between two dams in Korea. This option would secure water resources in a manner that minimizes the economic, environmental and social effects of water resource development and which maximizes the utility of existing water resources.     

Site modelling methods for detecting hydrologic alteration of flood frequency and flood duration in the floodplain below the carlyle dam,lower Kaskaskia River,Illinois, USA

Reports concerning the influence of dams on river hydrology vary among researchers, interest groups and government agencies. These often contradicting statements may occur because changes in hydrology caused by dams are distinct for each dam and river watershed. The objective of this research was to use site specific techniques to determine if the 1967 installation of the Carlyle Dam, lower Kaskaskia River, Illinois, altered flood frequency and duration within the forested floodplain located below the dam. Results indicated a decrease in flood duration and frequency, and a decrease in annual flood frequency variation at a site 6.4 km below the dam. Pre‐dam versus post‐dam differences in flood frequency and duration at the site 32.2 km below the dam were related to climate rather than dam effects. Although dam impacts are a concern, this research shows that distance downstream from the dam and downstream tributary and watershed characteristics should be considered before assuming that the dam has changed hydrologic parameters for portions of rivers. This research also indicates that areas of the lower Kaskaskia River may still maintain hydrologic ecological integrity, and could be targeted for restoration and adaptive management purposes. Hydrologic modelling combined with river gage and on‐site well measurement techniques presented in this study could provide detailed flood frequency and duration information for land use, sociological and geomorphological questions in focus areas within river floodplains. Copyright © 2008 John Wiley & Sons, Ltd.     

Historical development and the present status of Japanese dams

Dams have contributed to population growth and technological innovation by reducing the risk of flooding and allowing humans to cultivate productive alluvial soils on river floodplains. However, in countries where many dams have already been constructed, many problems have been observed, such as river environment degradation, aging of the embankments, and inadequate dam performance. As the social and natural environment surrounding dams is becoming more complex and diverse, it is necessary to understand the current overall status of dams and the history of their construction such that we may consider how social capital and dams are related to human society and the natural environment. In this study, the relationship of basic information of dams and the social background in which the dams exist was examined for Japan, where dam construction began in earnest in the late 1800s and became a driving force for economic development. The situations surrounding dams are drastically changing, as maintenance and management costs increase due to the aging of dams and water demand varies due to changes in the industrial structure of a region. Simultaneously, there are instances where dams are expected to reduce damage, such as in the presence of more severe and frequent droughts and floods caused by climate change. It is therefore necessary to remove or restructure dams while considering numerous complex and diverse factors, such as the local social conditions, potential future changes, and environmental impact of rivers.     

Informing Watershed Connectivity Barrier Prioritization Decisions: A Synthesis

Water resources and transportation infrastructure such as dams and culverts provide countless socio‐economic benefits; however, this infrastructure can also disconnect the movement of organisms, sediment, and water through river ecosystems. Trade‐offs associated with these competing costs and benefits occur globally, with applications in barrier addition (e.g. dam and road construction), reengineering (e.g. culvert repair), and removal (e.g. dam removal and aging infrastructure). Barrier prioritization provides a unique opportunity to: (i) restore and reconnect potentially large habitat patches quickly and effectively and (ii) avoid impacts prior to occurrence in line with the mitigation hierarchy (i.e. avoid then minimize then mitigate). This paper synthesizes 46 watershed‐scale barrier planning studies and presents a procedure to guide barrier prioritization associated with connectivity for aquatic organisms. We focus on practical issues informing prioritization studies such as available data sets, methods, techniques, and tools. We conclude with a discussion of emerging trends and issues in barrier prioritization and key opportunities for enhancing the body of knowledge. Copyright © 2016 John Wiley & Sons, Ltd.