AN ANALYSIS OF SEASONAL FECAL COLIFORM LEVELS IN THE TCHEFUNCTE RWER1

ABSTRACT: A model for estimating seasonal fecal coliform concentrations in the Tchefuncte River as a function of river discharge was developed. Data on fecal coliform concentration were obtained from the Louisiana Department of Health and Hospitals and were available for a period of 15 years (1975 through 1992) from three locations. Stream flow data were obtained from a gaging station of the U. S. Geological Survey at Folsom, Louisiana. These data were available for 49 years (1943 through 1991). The climate of the area is characterized by different precipitation/runoff mechanisms for the summer and winter seasons. The division for seasons used in this analysis was May through October (summer season), and November through April (winter season). Because of the combined effects of climatic mechanisms causing precipitation and the seasonal variation of evapotranspiration, runoff is greater in the winter season resulting in higher fecal coliform counts in the Tchefuncte River. Statistical analysis revealed a statistically significant relationship between fecal coliform concentration and discharge for each season, at each of three sites on the Tchefuncte River.     

CHARACTERISTICS AND CONTRIBUTING CAUSES OF AN ABNORMAL FREQUENCY OF FLOOD-PRODUCING RAINSTORMS AT CHICAGO1

ABSTRACT: Major hydrometeorological factors pertinent to defining and understanding the hydrologic characteristics of urban and other small-basin storms were investigated using data from a continuous 44-year operation of a recording raingage network in Chicago. Factors included: the frequency distribution of basin mean rainfall and its relation to storm maximum precipitation; the spatial distribution characteristics of each storm, including storm rainfall reduction factors which are widely used in hydrologic design problems; and weather-related causes related to the frequency and intensity of severe rainstorms in the Chicago area in recent years. Results have indicated that urban mean rainfall frequencies were overestimated in earlier studies in which they were derived from point/areal mean rainfall ratios obtained from much shorter records on rural networks. Reduction factors were found to vary between urban and rural storm systems due to urban-related effects. Two factors were found to be potential contributors to the characteristics of severe rainstorm occurrences at Chicago. These include urban-induced rain enhancement and an upward climatic trend in the occurrence of heavy rainfall events during the sampling period. Study results should be generally applicable to other large urban areas in the Midwest and other regions of similar precipitation climate.     

温室效应与全球变化（二）：应当限制哪些温室气体的排放？

自有大气层以来就有温室效应。工业革命以来，大量人为温室气体的排放使温室效应增强，全球海平面上升和气温上升。人类对这一过程的认识还有很大的不确定性。本文综述了到目前为止对这一问题进行科学研究的结论，指出在控制温室效应和全球变化的问题上，最困难也是最基本的难题是减少二氧化碳的排放。     

Bidirectional visibility

The percentage of the cross-sectional area of two objects (e.g., vehicles, hikers, or animals) that can be seen from each of their locations in a forested area is generally not the same. There is a directionality to the visibility between them. This is due to the relative positions and sizes of the vegetation and other view-blocking features between the objects. An analytical technique has been developed to help understand bidirectional visibility. Its use entails the construction of a visibility diagram containing the basic visibility information between observers in a given setting. An example is presented showing the use of the visibility diagram to determine visibility between two moving observers in a forested environment. The diagram is also used to determine the differences in the percentage each observer has of the other's visible cross-sectional area (bidirectional visibility). A discussion of the application of the technique in the planning or development of new facilities, as well as in forest and wildlife management, is provided.     

A strategy for integrated monitoring

Administrative machinery has been set up to regulate and control most of the emissions that are known to have severe local consequences, such as the discharge of raw sewage into rivers and lakes and the smokestack emission of air pollutants. Now, the nature of environmental degradation is usually different. We are faced with pollutants and effects with more subtle cause-effect relationships, often characterized by larger geographic areas of interest and longer term potential damage; the potential risk is now more chronic than acute. Acid rain and climate change are good examples, in that they are associated with a variety of pollutants from a number of sources and damage to ecosystems occurs over many years. It is argued that monitoring programs should evolve to reflect the changing nature of the environmental problems they are addressing. It is now necessary to consider interactions among many pollutants, mixing among the various media, and potentially affecting many components of the ecosystem in both indirect and direct ways. Here, integrated monitoring and analysis is presented as a unifying strategy to bring together different measurement methodologies in different disciplines, addressing environmental questions of complexity beyond the scope of many existing activites that have a classical narrower focus. The underlying concept is of nested networks, each tier being composed of sites selected for specific purposes but arranged to maximize the number of common sites where more multidisciplinary questions can be addressed.     

Livestock grazing and habitat for a threatened species: Land-use decisions under scientific uncertainty in the White Mountains,California, USA

The North Fork of Cottonwood Creek, in the White Mountains, Inyo National Forest, California, is a critically important refuge for the Paiute cutthroat trout (Oncorhynchus clarki seleniris), a federally listed threatened species. Habitat for these fish appears to be limited by excessive levels of fine sediment in the channel, and livestock grazing of riparian meadows has been implicated in delivery of sediment to the channel. However, the relationships between land use and sediment yield have not been conclusively determined, in large part because there are no historically ungrazed sites to serve as long-term controls. Accordingly, land-use decisions must be made under scientific uncertainty. To reduce erosion and sedimentation in the stream, the Forest Service spent approximately US$260,000 from 1981 to 1991 to repair watershed damage from livestock grazing, prevent livestock from traversing steep banks, and limit livestock access to the channel. Throughout this period, livestock grazing has continued on these lands, yielding less than $12,000 in grazing fees. In revising its Allotment Management Plan for the basin, the Forest Service rejected the “no-grazing” alternative because it was inconsistent with its Land and Resource Management Plan, which specifies there is to be no net reduction of grazing. Joint appointment with the University of California White Mountain Research Station, East Line Street, Bishop, California 93518, USA.     

Better environmental future in Europe through environmental auditing?

environmental auditing must be rejected if the aim is to make companies introduce a specific management concept. Rather, it is preferable to leave the search for effective environmental protection strategies to the competitive system, especially since the criteria for environment-oriented management in the European Community audit proposal are without substance. Environmental auditing can, however, assume a complementary function in the framework of an overall environmental policy if it is designed as an information tool with which companies provide information on the development of environmental problems deriving from their manufacturing processes and products. However, the model required to establish a framework of quantity and evaluation criteria is not available. Further, auditing does not cover products. Similarly, there are no proposals defining the evaluation procedure for ecological resource scarcity. Thus, the attempt of the Commission of the European Communities to create the elementary prerequisites for consistent and verifiable environmental auditing in the corporate sector has failed.     

ADVANTAGES AND DISADVANTAGES OF REGIONAL SEWERAGE SYSTEMS1

ABSTRACT: A few years ago, many water quality administrators were convinced that large regional sewerage systems, consisting of one large treatment plant and long trunk sewers extending out to various communities, represented the only efficient and economical means of assuring water quality control. In communities favoring rapid development, the provision of sewer service and encouragement of development of new centers along the trunk sewers offered an additional advantage. More recently quite different points of view are arising in certain areas. In parts of New Jersey strong environmental and community resistance has arisen to proposed central plant-trunk sewer systems. The facilitation of new development along the trunk sewers is viewed as a menace by townships not wanting intensive development of these areas. The diversion of effluent flows to trunk sewers rather than septic tanks would dry up the streams which water quality programs are supposed to protect. Both sides to the controversy have mobilized engineering, environmental, economic, and legal expertise and some critical policy issues have developed. Reconsideration of regional sewerage management and particularly trunk sewer policy is required. The decision as to extent of sewerage service areas involves complex and sensitive planning issues. Because of potential conflicts of interest, such decisions should not be left to staffs of sewerage authorities and their design engineers.     

WATER YIELD IMPROVEMENT BY VEGETATION MANAGEMENT1

ABSTRACT: Vegetation management aimed at increasing the amount of usable water yield from precipitation falling on upstream watersheds may be one alternative for supplementing water supplies. Indications are that water yields can be increased within a multiple-use framework, which can benefit or at least be compatible with other natural resource objectives. Through changes in vegetation on a watershed, it is possible to reduce evaporation losses only slightly but significantly increase streamflow runoff. In an assessment of potentials for water yield improvement in Arizona, experimental studies on various vegetation zones are reviewed. Because of either limited acreage or limited rainfall, the alpine, grassland, aspen, and desert shrub vegetation zones are not realistic management areas for Arizona. Furthermore, manipulation of pinyon-juniper woodlands does not appear promising at this time. Conversion of chaparral to grasses and forbs does appear to be a possible treatment for water yield improvement, as well as various silvicultural treatments of mixed conifer and ponderosa pine forests. Streamflow increases are given for experiments in chaparral, mixed conifer, and ponderosa pine vegetation zones. However, complete information on possible constraints for these zones is not currently available. Specific assessment of water yield management options for riparian vegetation is difficult to make, due to incomplete knowledge of water yield changes and other constraints for this vegetation zone. Prior to the final adoption of management practices, results of experimental work must be coupled with economic and social considerations.