长期以来，人们主要考虑水资源在农业、工业和生活等方面所产生的国民经济效益，而对于维护河流与流域健康的生态环境需水方面则缺少足够的重视。水资源不合理的开发利用加速了水体功能的衰减和退化，使水资源短缺、水体污染严重、生态环境脆弱，旱涝灾害频发等问题日益严峻，严重制约着我国经济社会可持续发展战略的实施。为缓解生态环境不断恶化的现状，维持河流的健康生命，河流生态基流问题逐渐引起水资源管理部门以及各级政府的高度重视，并成为当今水文水资源、生态、环境等领域的研究热点和难点之一，也是本研究需解决的重大关键科学问题。河流生态基流研究涉及到水文、气候、地质、水资源开发利用、生态环境保护以及社会经济发展等多学科的科学问题。目前，河流生态基流研究正处于起步阶段，其概念与内涵、确定原则、计算方法以及保障措施等仍没有达成共识。因此，深入开展生态基流研究不仅具有重要的科学价值，也为规范生态基流的评估方法作出贡献，并最终为水资源及水环境管理提供理论支撑。 在研究实施过程中，利用外方在植物群落演替分析、水沙—水质耦合模拟技术以及生态基流量计算的敏感性和不确定性分析方面的先进技术，由中方进行水文分析和水量模拟，建立生态评估指标体系，共同建立集成的生态水文过程模拟模型，评估利益相关方在用水计划和生态基础流量方面的利益和冲突，确定生态系统保护目标，估算渭河流域生态保护目标所需生态基流，确定当地生态基础流量，进行不确定性和敏感性分析，以期为渭河流域水资源水环境综合管理提供理论依据和技术支撑。 Around the world,there is increasing desire to conserve or restore the ecological health and functioning of rivers and their associated wetlands for human use and biodiversity.To achieve this,many methods have been developed for defining EFR,i.e.the flow regime required in a river to achieve desired ecological objectives.EFR is often seen as the vehicle through which the interests of the ecosystem,or the nature itself,are expressed.But it has also been increasingly recognized that an integrated river management has the task to ensure that each of the relevant environmental and economic functions is sustained in a balanced way.This renders the determination of an appropriate level of EFR a multi-disciplinary task that involves both natural and social science dimensions.However,existing EFR studies have been so far mainly conducted from the natural science perspective.In many countries,such as China,the social perspective is almost completely absent in the hitherto EFR studies. The overall objectives of the proposed project are to develop estimation methods for environmental flow requirement(EFR)appropriate to the characteristics of the Wei River in China,to put forward protection measures to safeguard environment flow,and to provide theoretical guidance and technical support for restoring healthy ecosystem of the river.The following are the specific goals to be achieved in line with these objectives:1)Develop and provide solid scientific and appropriate estimation methods for EFR of the Wei River;2)Establish an index system and determine the major ttributes of individual indicators for the assessment of ecosystem health of the river;3)Quantify the social and economic impacts of different levels of environmental flow allocation on the economic sectors,in particular agriculture/irrigation,under various water allocation and management plans;4)Determine the ecologically sound and practically realistic level of EFR for the Wei River,with involvement of stakeholder interests in the river basin;5)Incorporate uncertainty and sensitivity analysis procedures in the determination of EFR and the relevant analysis.6)Provide solid theoretical bases,state of the art techniques,and practically feasible protection measures for safeguarding the desired environmental flow in the river.

Environmental pollution problems are crucial concerns that have attracted a great deal of public attention. More actions are urgently required on formulating remediation strategies for contaminated sites and setting effective standards and regulations for reducing the toxic pollutants in the environment. To achieve these needs, comprehensive understanding of and characterizing the natural behavior of chemical in the environment are essential tasks for environmental risk assessment and management. Compared with direct multimedia monitoring, multimedia-modeling systems are more viable and practicable. In this article, most widely recognized multimedia models were categorized and reviewed. The concepts that form the foundation of each multimedia model were described, and the advantages and the limitations of multimedia model were discussed. The aim of this article was to consider challenges and opportunities in improving present multimedia modeling system and also to pave the way for future research in this field.

The catchment water-energy balance at the interannual scale remains a challenge for bridging the important gap in our knowledge of the hydrologic cycle. This study investigates interannual evapotranspiration (ET) variability and water-energy balance at over 547 catchments across the contiguous United States in different climate zones. The investigation is based on ET data estimated from satellite images and surface daily meteorological data during the period of 1983-2006 provided by the University of Montana. We find that the interannual relationship between annual potential ET to annual precipitation (PET/P) and ET/P, the energy, and water factors defined with the Budyko curve framework can be captured by a linear function, with an average goodness of fit of 0.928 over all the catchments. The linear relationship is validated by another independent remote sensing ET product generated by the University of Washington and is demonstrated to be rational using regression diagnostics. Additionally, a comparison study using a water balance method and the Budyko curve is undertaken to examine the linear relationship. In addition to water supply and energy supply, the primary controls on evapotranspiration, soil water storage, response of vegetation to climate variability, and human interference are also major factors of the interannual relationship between PET/P and ET/P.

Estimation of instream flow requirements for sediment transport (IFRST) in the downstream Weihe River is important for the maintenance of a healthy ecosystem of the river. In this study, the IFRST for the lower Weihe River is estimated on the basis of the observed hydrological data during the period 1960-2001. The results showed that the mean annual IFRSTs for the reach between Lintong and Huaxian and the reach below Huaxian were 6.85 and 7.62 billion m(3)/year, respectively, and the standard errors were 0.50 and 0.76 billion m(3)/year, respectively. The results also showed that the Sanmenxia Reservoir is an important driver for the changes in channel morphology and hydraulics, as well as the IFRST. Furthermore, according to the hydrological frequency (p value) estimated from annual instream flow data during the period 1960-2001, four typical years (p = 25%, 50%, 75% and 90%) for the two reaches of the Weihe River were determined. The analysis showed that the IFRST has a negative power functional relationship with the sediment concentration. On the basis of the efficiency coefficients (R(2)) during three sub-periods 1960-1973, 1974-1990 and 1991-2001, the annual IFRSTs in the above two reaches for the four typical years were estimated under different deposition and erosion-deposition conditions. The results provide useful references for restoration and water resource management of the Weihe River. Copyright (C) 2010 John Wiley & Sons, Ltd.