Recommended design for more accurate duplication of natural conditions in salt marsh creation

Construction of 653 ha of salt marsh habitat from dredged material near the Aransas National Wildlife Refuge, Texas, has been proposed, with the goal of increasing the area of habitat available to endangered whooping cranes (Grus americana). We assessed prototype created wetlands, and their similarity to natural reference sites, in terms of topography, vegetation, and hydrology. The created sites were steeply sloped relative to natural sites and were dominated by monotypic stands of Spartina alterniflora. Natural sites were dominated by vegetation more tolerant of desiccation and hypersalinity and by unvegetated salt pans. Differences in vegetation communities and distributions of habitat types resulted from efforts to enhance habitat diversity in created marsh cells through manipulation of marsh topography. However, the scale at which this diversity occurred in natural marsh of the study area was not considered. When constructing wetlands in cellular configurations, we recommend creation of large complexes of adjoining, hydrologically linked, cells wherein the desired habitat diversity is created at the scale of the entire complex, rather than within a single cell. Suggested design modifications would increase the similarity of created marshes to natural reference sites, potentially improving habitat function.     

From Superfund Site to Developable Property: The Case of Rentokil

The Comprehensive Environmental Response, Compensation, and Liability Act (42 USC §§9601 et seq.), commonly known as Superfund, was enacted on 11 December 1980 to facilitate the clean-up of hazardous waste sites. Superfund authorizes the Environmental Protection Agency (EPA) to compel responsible parties to clean up such sites. Superfund has been the source of extensive criticism since its inception. In response to this criticism, the EPA undertook a series of administrative reforms in 1993 to make the Superfund programme faster, fairer and more efficient. As of September 2000, active site remediation was complete at 757 (43%) of the 1779 national priority list (NPL) sites and 218 sites (12%) had been deleted from the NPL. Rentokil, a former wood-preserving plant on a 10 acre (4 ha) site in Henrico County, Virginia, was brought to the Virginia Health Department's attention as a threat to human health and the environment in 1989, was listed on the NPL the same year and was fully cleaned up in 1999. The cost of cleaning up Rentokil was $12 million, or $37.08 per square foot ($412 per square metre). The site is proposed to be redeveloped for tax-generating light industrial and commercial use. Rentokil reflects the EPA's implementation of several reforms geared toward reconciling cost considerations with remedy effectiveness and expedient implementation, and facilitating redevelopment. This case study's examination of Rentokil's progression through the Superfund process is intended to provide planning practitioners and students with insight into the Superfund programme and process, as well as an awareness of the challenges confronting Superfund's success.     

HYDRAULIC GEOMETRY RELATIONSHIPS FOR URBAN STREAMS THROUGHOUT THE PIEDMONT OF NORTH CAROLINA1

ABSTRACT: Hydraulic geometry relationships, or regional curves, relate bankfull stream channel dimensions to watershed drainage area. Hydraulic geometry relationships for streams throughout North Carolina vary with hydrology, soils, and extent of development within a watershed. An urban curve that is the focus of this study shows the bankfull features of streams in urban and suburban watersheds throughout the North Carolina Piedmont. Seventeen streams were surveyed in watersheds that had greater than 10 percent impervious cover. The watersheds had been developed long enough for the streams to redevelop bankfull features, and they had no major impoundments. The drainage areas for the streams ranged from 0.4 to 110.3 square kilometers. Cross‐sectional and longitudinal surveys were conducted to determine the channel dimension, pattern, and profile of each stream and power functions were fitted to the data. Comparisons were made with regional curves developed previously for the rural Piedmont, and enlargement ratios were produced. These enlargement ratios indicated a substantial increase in the hydraulic geometry for the urban streams in comparison to the rural streams. A comparison of flood frequency indicates a slight decrease in the bankfull discharge return interval for the gaged urban streams as compared to the gaged rural streams. The study data were collected by North Carolina State University (NCSU), the University of North Carolina at Charlotte (UNC), and Charlotte Storm Water Services. Urban regional curves are useful tools for applying natural channel design in developed watersheds. They do not, however, replace the need for field calibration and verification of bankfull stream channel dimensions.     

Modeling negative affectivity and job stress: a contingency‐based approach

Understanding the role of negative affectivity (NA) in relations between job stressors and resultant strains has been a major source of research interest in the organizational literature for almost two decades. In this study, we propose a contingency approach, whereby the role of NA depends on the nature of the strain construct under investigation. Specifically, we predicted that perceived job stressors would fully mediate the relationship between NA and turnover intentions, while job stressors would only partially mediate the relationship between NA and job and life satisfaction, and job stressors would be unrelated to depression once NA was taken into account. The relative fit of these four models is tested utilizing data from two divergent samples (sales representatives and managers) employing both self‐ and informant reports of strain measures where feasible. Hypotheses regarding the specified nature of the NA → stressor → strain relationship generally were supported and replicated across samples. In addition, an alternate model specifying that NA moderates the relationship between stressors and strains was not supported for any strain variable. Copyright © 2004 John Wiley & Sons, Ltd.     

Implementing Sustainability: the Use of Natural Channel Design and Artificial Wetlands for Stormwater Management

Sustainability is a concept that has been widely embraced both politically and intellectually but has not been addressed in terms of practical application. In most resource sectors, the features of a sustainable future remain unclear and there are few examples that give practical expression to sustainability. This is especially true in the case of water resources management which has been conspicuous in its absence from the majority of the literature. This paper attempts to address this deficiency on two counts. First, it provides a discussion of sustainability and the application of the concept to the management of water resources. Second, the paper illustrates how the concept can be utilized for the management and planning of urban stormwater. The paper concludes by offering research opportunities to investigate the feasibility of adopting natural channel design and artificial wetlands for sustainable stormwater management.     

NEW ZEALAND'S NATIONAL WATER QUALITY MONITORING NETWORK - DESIGN AND FIRST YEAR'S OPERATION1

ABSTRACT: The design and implementation of a national surface water quality monitoring network for New Zealand are described. Some of the lessons learned from the first year of operation are also addressed. Underpinning the design, and specified in advance, are the goal and objectives, the data quality assurance system, and the mechanism for data interpretation and reporting. Because of the difficulties associated with the use of a multitude of different agencies, only one agency is involved in field work and one laboratory undertakes the analysis. Staff training has been given a high priority. The network has been designed to give good trend detectability for regular sampling over a 5–10 year period.     

A role and expectancy model of participative decision-making: A replication and theoretical extension

Schuler's process model of employee participation in decision-making and job satisfaction (Schuler, 1980; Lee and Schuler, 1982) was tested using a path analytic approach. Reanalysis of Schuler's data and replication on a new sample indicated that (a) participation in decision-making has both direct and indirect effects on job satisfaction; and (b) performance–outcome expectancy, role conflict, and role ambiguity all appear to mediate the relationship between participation and satisfaction. In an extension of the model, organizational level and job involvement were hypothesized to moderate the participation–satisfaction relationship (i.e. function interactively). Although neither variable functions as a moderator, job involvement operates in a fashion similar to participation in the model. In general, consistent results across four independent samples strongly support Schuler's basic process model.     

Ecological limitations and appropriation of ecosystem support by shrimp farming in Colombia

Shrimp farming in mangrove areas has grown dramatically in Asia and Latin America over the past decade. As a result, demand for resources required for farming, such as feed, seed, and clean water, has increased substantially. This study focuses on semiintensive shrimp culture as practiced on the Caribbean coast of Colombia. We estimated the spatial ecosystem support that is required to produce the food inputs, nursery areas, and clean water to the shrimp farms, as well as to process wastes. We also made an estimate of the natural and human-made resources necessary to run a typical semiintensive shrimp farm. The results show that a semiintensive shrimp farm needs a spatial ecosystem support—the ecological footprint—that is 35–190 times larger than the surface area of the farm. A typical such shrimp farm appropriates about 295 J of ecological work for each joule of edible shrimp protein produced. The corresponding figure for industrial energy is 40:1. More than 80% of the ecological primary production required to feed the shrimps is derived from external ecosystems. In 1990 an area of 874–2300 km² of mangrove was required to supply shrimp postlarvae to the farms in Colombia, corresponding to a total area equivalent to about 20–50% of the country’s total mangrove area. The results were compared with similar estimates for other food production systems, particularly aquacultural ones. The comparison indicates that shrimp farming ranks as one of the most resource-intensive food production systems, characterizing it as an ecologically unsustainable throughput system. Based on the results, we discuss local, national, and regional appropriation of ecological support by the semiintensive shrimp farms. Suggestions are made for how shrimp farming could be transformed into a food production system that is less environmentally degrading and less dependent on external support areas.     

SIMULATION OF INTEGRATED SURFACE WATER AND GROUND WATER SYSTEMS - MODEL FORMULATION1

ABSTRACT: The unique characteristics of the hydrogeologic system of south Florida (flat topography, sandy soils, high water table, and highly developed canal system) cause significant interactions between ground water and surface water systems. Interaction processes involve infiltration, evapotranspiration (ET), runoff, and exchange of flow (seepage) between streams and aquifers. These interaction processes cannot be accurately simulated by either a surface water model or a ground water model alone because surface water models generally oversimplify ground water movement and ground water models generally oversimplify surface water movement. Estimates of the many components of flow between surface water and ground water (such as recharge and ET) made by the two types of models are often inconsistent. The inconsistencies are the result of differences in the calibration components and the model structures, and can affect the confidence level of the model application. In order to improve model results, a framework for developing a model which integrates a surface water model and a ground water model is presented. Dade County, Florida, is used as an example in developing the concepts of the integrated model. The conceptual model is based on the need to evaluate water supply management options involving the conjunctive use of surface water and groundwater, as well as the evaluation of the impacts of proposed wellfields. The mathematical structure of the integrated model is based on the South Florida Water Management Model (SFWMM) (MacVicar et al., 1984) and A Modular Three-Dimensional Finite-Difference Groundwater Flow Model (MODFLOW) (McDonald and Harbaugh, 1988).     

Automatic safety belt use in Michigan: A two-year follow-up

The use of automatic safety belts among motorists throughout the state of Michigan was examined as part of a broader direct observation survey to measure compliance with the state's mandatory belt use law. Use of the most common types of automatic belt systems were measured: the nonmotorized detachable three-point lap and shoulder belt system, and the two-belt system with either a motorized shoulder belt and manual lap belt or a nonmotorized shoulder belt and manual lap belt. Belt use rates in vehicles with and without air bags were also compared. A total of 1,367 drivers and front-right passengers were observed with automatic belt systems between June 1 and July 11, 1992. Use of nonmotorized detachable three-point lap and shoulder belt systems was 72.3%. Lap belt use of motorized shoulder and manual lap belt systems was 70.5%. Lap belt use of nonmotorized shoulder and manual lap belt systems was 60.2%. Of all motorized and nonmotorized shoulder belt and manual lap belt systems observed, 94.5% had the shoulder belts connected.