Linking Theory and Practice for Restoration of Step-Pool Streams

Step-pools sequences are increasingly used to restore stream channels. This increase corresponds to significant advances in theory for step-pools in recent years. The need for step-pools in stream restoration arises as urban development encroaches into steep terrain in response to population pressures, as stream channels in lower-gradient areas require stabilization due to hydrological alterations associated with land-use changes, and as step-pools are recognized for their potential to enhance stream habitats. Despite an increasingly voluminous literature and great demand for restoration using step-pool sequences, however, the link between theory and practice is limited. In this article, we present four unique cases of stream restoration using step-pools, including the evolution of the approaches, the project designs, and adjustments in the system following restoration. Baxter Creek in El Cerrito, California demonstrates an early application of artificial step-pools in which natural adjustments occurred toward geomorphic stability and ecological improvement. Restoration of East Alamo Creek in a large residential development near San Ramon, California illustrates an example of step-pools increasingly used in locations where such a channel form would not naturally occur. Construction of a step-pool channel in Karnowsky Creek within the Siuslaw National Forest, Oregon overcame constraints posed by access and the type and availability of materials; the placement of logs allowed natural scouring below steps. Dry Canyon Creek on the property of the Mountains Restoration Trust in Calabasas, California afforded a somewhat experimental approach to designing step-pools, allowing observation and learning in the future. These cases demonstrate how theories and relationships developed for step-pool sequences over the past two decades have been applied in real-world settings. The lessons from these examples enable us to develop considerations useful for deriving an appropriate course of design, approval, and construction of artificial step-pool systems. They also raise additional fundamental questions concerning appropriate strategies for restoration of step-pool streams. Outstanding challenges are highlighted as opportunities for continuing theoretical work.     

Towards greening a university campus: The case of the University of Maribor, Slovenia

The environmental performance of the University of Maribor (Engineering Campus) has been assessed on a life cycle basis. The following activities have been considered in the study: the use and operation of lecture theatres (construction and maintenance, heating, lighting and water consumption) and day-to-day consumption of sundries (paper and plastic bottles). The results indicate that the heating and construction of buildings are the ‘hot spots’ in the system, for most environmental impacts. Different waste management options for the plastic and paper, including recycling, incineration and landfill, have also been compared for environmental impacts and economic costs. The option combining 70% recycling, 29% incineration and 1% landfill has been found to be most economically and environmentally sustainable.     

An integrated assessment modeling framework for assessing primary and secondary impacts from carbon dioxide stabilization scenarios

As the nations of the world negotiate future controls on greenhouse gas emissions, a critical environmental policy issue becomes understanding the multiple environmental consequences of these controls. Here we describe an integrated assessment model for quantifying multiple environmental impacts of large-scale environmental initiatives and apply this model to climate change mitigation. Our analysis shows that reductions in global warming will be accompanied by reductions in ozone depletion, acid rain and mercury emissions, and desulfurization waste generation. We also conclude that the largest collateral benefits from reducing global climate change may be in the developing world. This result is critical since it is the developing nations who ultimately control the long-term success of any climate stabilization strategy. This revised version was published online in July 2006 with corrections to the Cover Date.     

CLIMATIC CHANGE AND U.S. WATER RESOURCES: FROM MODELED WATERSHED IMPACTS TO NATIONAL ESTIMATES1

ABSTRACT: Water is potentially one of the most affected resources as climate changes. Though knowledge and understanding has steadily evolved about the nature and extent of many of the physical effects of possible climate change on water resources, much less is known about the economic responses and impacts that may emerge. Methods and results are presented that examine and quantify many of the important economic consequences of possible climate change on U.S. water resources. At the core of the assessment is the simulation of multiple climate change scenarios in economic models of four watersheds. These Water Allocation and Impact Models (Water‐AIM) simulate the effects of modeled runoff changes under various climate change scenarios on the spatial and temporal dimensions of water use, supply, and storage and on the magnitude and distribution of economic consequences. One of the key aspects and contributions of this approach is the capability of capturing economic response and adaptation behavior of water users to changes in water scarcity. By reflecting changes in the relative scarcity (and value) of water, users respond by changing their patterns of water use, intertemporal storage in reservoirs, and changes in the pricing of water. The estimates of economic welfare change that emerge from the Water‐AIM models are considered lower‐bound estimates owing to the conservative nature of the model formulation and key assumptions. The results from the Water‐AIM models form the basis for extrapolating impacts to the national level. Differences in the impacts across the regional models are carried through to the national assessment by matching the modeled basins with basins with similar geographical, climatic, and water use characteristics that have not been modeled and by using hydro‐logic data across all U.S. water resources regions. The results from the national analysis show that impacts are borne to a great extent by nonconsumptive users that depend on river flows, which rise and fall with precipitation, and by agricultural users, primarily in the western United States, that use a large share of available water in relatively low‐valued uses. Water used for municipal and industrial purposes is largely spared from reduced availability because of its relatively high marginal value. In some cases water quality concerns rise, and additional investments may be required to continue to meet established guidelines.     

跨流域调水的公正问题——基于环境正义的分析视角

水资源时空分布不均造成的水资源短缺问题已成为阻碍区域发展的重要因素。为了应对区域间的水资源短缺问题,跨流域调水工程作为不同流域水资源优化配置的一种手段,被广泛用于解决水资源分配不均和区域需水不平衡问题。调水工程虽然短期内缓解了水资源压力,平衡了区域间用水需求,但其建设和运营过程对工程所涉区域的地方经济、地理环境、人文环境以及生态环境也造成不同程度的压力。本文通过对当前世界范围内跨流域调水工程的文献回顾,围绕跨流域调水工程所引发的社会公平正义层面的争议,借助环境正义理论的分析方法,通过对国内外调水案例的实践分析,追踪相关环境不公的现象和争议,剖析当前社会—生态冲突的产生机制。最后从我国水生态文明建设实际出发,提出以建立健全水权交易市场,构建"赋权—认同—合作"参与机制和树立"人类命运共同体"理念的解决对策,以期降低调水工程对环境和社会所造成的负面影响,推进水生态正义体系的建设。     

WATER QUALITY IMPACTS OF CONSERVATION AGRICULTURAL PRACTICES IN THE MISSISSIPPI DELTA1

ABSTRACT: Nonpoint pollution in the form of runoff generated by conventional agricultural practices is one of the major sources of environmental degradation of surface water bodies. Agricultural conservation practices including no‐tillage operations have been introduced as alternatives to cope with such challenges. This study attempts to examine the economic and environmental impacts of no‐tillage as compared to conventional agricultural practices for cotton, soybeans and corn cultivated in the Mississippi Delta. Impacts in the form of sediment, nutrient and pesticide runoff at farm level are investigated, using the Erosion Productivity Impact Calculator (EPIC).     

中国钢材生命周期清单分析

采用生命周期清单分析方法分析了我国普通钢材生产过程中的能源消耗，物料消耗以及对环境的排放，研究表明我国钢铁生产生命周期过程中值得关注的环境问题有：能源消耗远高于发达国家平均水平，其主要存在于各相连工艺间及内部的运输过程水循环利用率较低，造成大量淡水资源浪费；废气排放主要是CO2和SOx，其主要来源于煤的燃烧和工艺过程，十分巨大的工业固体废弃物将造成严峻的局地环境问题。     

西藏那曲至嘉黎公路改建工程环境影响分析及环保对策

针对青藏高原生态环境的特殊性，分析了藏北高原公路建设的环境影响，提出了公路施工环境管理及环境保护措施。     

基于CGE模型的供水投资对经济影响研究——以黑龙江省为例

为缓解水资源供需矛盾,我国政府投入大量资金兴修水利。如何评价供水投资效果及其对国民经济产生的影响,以便于确定合理的投资定位与投资决策,已成为目前亟待解决的热点问题之一。构建黑龙江省静态CGE模型,根据黑龙江省近几年供水投资实际增长规模设计三种投资方案,定量估算一定的供水投资政策对黑龙江省经济总量、其他部门投资、不同部门的总产出和供用水量的潜在影响,结果表明:①供水部门投资能拉动国民经济发展,当投资增长规模约为40%~50%时,GDP增长速率最大;②供水部门投资增长会拉动高用水工业和农业部门投资上涨,导致一般用水工业、建筑业、一般用水服务业和高用水服务业投资下降;③各部门总产出增长率大小依次为高用水工业、高用水服务业、一般用水服务业、农业和建筑业,各部门用水量增长最快的是高用水工业,其次为高用水服务业、一般用水服务业和建筑业;④黑龙江省供水部门投资增长规模大于43%时,供水部门总产出方能满足用水需求,有利于保证城镇供水安全。综合GDP增长速率考虑,黑龙江省适宜的供水投资增长规模应为43%~50%。     

涉及国家级自然保护区建设项目的累积生态影响研究

通过对近一年来我国涉及国家级自然保护区建设项目的统计分析,探析了多个建设项目对单个自然保护区累积生态影响的具体内容,并以内蒙古西鄂尔多斯国家级自然保护区为例,探讨了累积生态影响的评价方法。最后为严格控制建设项目对国家级自然保护区的累加生态影响,提出了4条有针对性的建议对策。