Regulatory context for cumulative impact research

Wetlands protection has become a topic of increased public attention and support, and regulation of wetlands loss under Section 404 of the Clean Water Act has received high priority within the US Environmental Protection Agency (EPA). Despite this, the nation is continuing to experience serious wetlands losses. This situation reflects the contentious nature of wetlands protection; it involves fundamental conflicts between environmental and development interests. Better information is needed to support regulatory decision making, including information on cumulative impacts. Currently, consideration of cumulative impacts, although required by various federal regulations, is limited. One reason is that most regulatory decisions are made on a permit-specific, site-specific basis, whereas cumulative impacts must be assessed on a broader, regional scale. In addition, scientific information and methods necessary to support cumulative impact assessment have been lacking. An anticipatory, planning-oriented framework to complement the existing site-specific permit review program is needed to support more effective consideration of cumulative impacts; such an effort is beginning to emerge. In addition, EPA is supporting research to provide better information on cumulative effects. It is recommended that the EPA program place initial emphasis on synthesis and analysis of existing information, on maximizing its use in decision making, and on information transfer. Recommended approaches include correlation of historic wetlands losses with loss of wetlands function and values, regional case studies, and development of indices of cumulative impact for use in permit review.Formerly Director, Office of Federal Activities, US Environmental Protection Agency     

水射流技术在放顶煤综采中的应用

介绍水射流技术在放顶煤综采中的应用。通过具体的技术经济指标说明在一定的条件下水系与放顶煤综采相结合是提高采煤效益的新途径。还说明，水射流技术在采矿工业中有着广阔的应用前景。     

XK—1．5型除尘清洗两用机的研究、试验与应用

采用高压水和喷嘴的引射原理，使水射流通过喷嘴后高效雾化，达到降尘的目的，并主要沉降５μｍ以下对人体具有致命危害的呼吸性粉尘。当更换喷嘴后也可进行积上和物体的表面清洗。     

成都市青白江区水环境保护与管理的现状及防治对策

本文报道了沱江上游青白江区水环境管理的现状，分析了水环境管理中存在的问题，提出了防治对策。     

The new regime for managing US—Mexican water resources

United States-Mexican transboundary water resources management is presently experiencing significant reform resulting from long-term demographic processes in the border region and greater economic integration. The recently concluded North American Free Trade Agreement and supplementary environmental accord modify existing agreements and provide old institution with new mandates. Particularly affected is the International Boundary and Water Commission (IBWC), long the lead agency in binational water management. This essay reviews the development of the new water management regime against the two preceding phases of management reform and considers its implications for improved water management in the border region.     

Evaluating the effects of spatial monitoring policy on groundwater quality portrayal

What size sample is sufficient for spatially sampling ambient groundwater quality? Water quality data are only as spatially accurate as the geographic sampling strategies used to collect them. This research used sequential sampling and regression analysis to evaluate groundwater quality spatial sampling policy changes proposed by California's Department of Water Resources. Iterative or sequential sampling of a hypothetical groundwater basin's water quality produced data sets from sample sizes ranging from 2.8% to 95% coverage of available point sample sites. Contour maps based on these sample data sets were compared to an original (control), mapped hypothetical data set, to determine at which point map information content and pattern portrayal are not improved by increasing sample sizes. Comparing series of contour maps of ground water quality concentration is a common means of evaluating the geographic extent of groundwater quality change. Comparisons included visual inspection of contout maps and statistical tests on digital versions of these map files, including correlation and regression products. This research demonstrated that, down to about 15% sample site coverage, there is no difference between contour maps produced from the different sampling strategies and the contout map of the original data set.     

Restoration ecology of riverine wetlands: II. An example in a former channel of the Rhône River

Riverine wetlands, which provide numerous valuable functions, are disappearing in floodplains of a channelized European river. A restoration project has been proposed by scientists to restore a former braided channel of the Rhône River by the removal of fine organic sediments in order to enhance groundwater supply. A precise and intensive prerestoration monitoring program during one year (including comparison with a reference channel) has taken into account several variables and ecological performance indicators measured at various spatial and temporal scales. Three restoration techniques were then suggested, taking into account two characteristics of ecosystem functions for increasing restoration success and self-sustainability: (1) the riparian forest as well as the shores must be preserved or disturbed as little as possible; and (2) the upstream alluvial plug must be preserved to prevent direct supply of nutrientrich water from the Rhône River. Among the three restoration options proposed, it was not possible to carry out the less ecologically disturbing one as it was considered too expensive, time consuming, and difficult to realize. A precise and intensive postrestoration monitoring program, conducted over two years, demonstrated restoration success but also unpredicted problems, such as a locally thick layer of fine organic sediment. As long as a self-sustainable state is not achieved, this monitoring should be continued. Afterwards, a less precise and less intensive long-term monitoring should enable the detection of future events that may influence ecosystem changes.     

Agriculture and stream water quality: A biological evaluation of erosion control practices

Agricultural runoff affects many streams in North Carolina. However, there is is little information about either its effect on stream biota or any potential mitigation by erosion control practices. In this study, benthic macroinvertebrates were sampled in three different geographic areas of North Carolina, comparing control watersheds with well-managed and poorly managed watersheds. Agricultural streams were characterized by lower taxa richness (especially for intolerant groups) and low stability. These effects were most evident at the poorly managed sites. Sedimentation was the apparent major problem, but some changes at agricultural sites implied water quality problems. The groups most intolerant of agricultural runoff were Ephemeroptera, Plecoptera and Trichoptera. Tolerant species were usually filter-feeders or algal grazers, suggesting a modification of the food web by addition of particulate organic matter and nutrients. This study clearly indicates that agricultural runoff can severely impact stream biota. However, this impact can be greatly mitigated by currently recommended erosion control practices.     

CHANGES IN WATER POLICY IN THE PEOPLE'S REPUBLIC OF CHINA1

ABSTRACT: Ideology has predisposed the People's Republic of China against the use of prices to allocate water. Prolonged drought in north China has made the Chinese more aware of their unfavorable water resource inventory and the expense of expanding supply. Therefore, as part of the economic liberalization commenced since the death of Mao Zedong, China has started to make more active use of pricing to regulate demand and reduce the need for supply expansion.     

COMPARISON OF PROCESS‐BASED AND ARTIFICIAL NEURAL NETWORK APPROACHES FOR STREAMFLOW MODELING IN AN AGRICULTURAL WATERSHED1

ABSTRACT: The performance of the Soil and Water Assessment Tool (SWAT) and artificial neural network (ANN) models in simulating hydrologic response was assessed in an agricultural watershed in southeastern Pennsylvania. All of the performance evaluation measures including Nash‐Sutcliffe coefficient of efficiency (E) and coefficient of determination (R²) suggest that the ANN monthly predictions were closer to the observed flows than the monthly predictions from the SWAT model. More specifically, monthly streamflow E and R² were 0.54 and 0.57, respectively, for the SWAT model calibration period, and 0.71 and 0.75, respectively, for the ANN model training period. For the validation period, these values were ?0.17 and 0.34 for the SWAT and 0.43 and 0.45 for the ANN model. SWAT model performance was affected by snowmelt events during winter months and by the model's inability to adequately simulate base flows. Even though this and other studies using ANN models suggest that these models provide a viable alternative approach for hydrologic and water quality modeling, ANN models in their current form are not spatially distributed watershed modeling systems. However, considering the promising performance of the simple ANN model, this study suggests that the ANN approach warrants further development to explicitly address the spatial distribution of hydrologic/water quality processes within watersheds.