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).     

ASSESSING POTENTIAL SOURCES OF ASBESTOS FIBERS IN WATER SUPPLIES OF S. E. QUEBEC1

ABSTRACT: A comparative study of the concentration of asbestos fibers in drinking water supplies of southeastern Quebec was undertaken to assess the relative contributions of fibers by asbestos-bearing railway ballast and naturally occurring asbestos deposits. Water samples were taken from areas where one or the other potential sources or neither potential source was present. In addition, rainwater samples were taken to assess the importance of atmospheric contributions. The sampling design accounted for potential variations in fiber counts due to the season, location and analytical procedures. Fiber concentrations were estimated from counts made on a JEOL 100CX scanning transmission electron microscope and statistically compared among areas. These levels were then compared with levels found in other areas of Canada and the United States. The results indicate that the rail ballast could be contributing statistically (albeit marginally) significant quantities of fibers to water supplies during the summer but not in the spring. Estimated concentrations in water supplies ranged between 1.7 × 10⁶fibers/liter and 147.8 × 10⁶fibers/liter. Fiber levels in samples taken during the spring were significantly higher and more variable than those taken during the summer. The presence of fibers in rainwater samples at concentrations of 1.9 × 10⁶fibers/liter, 18.3 × 10⁶fibers/liter and 23.7 × 10⁶fibers/liter suggests that atmospheric transport may play an important role in contributing fibers to regional systems. Fiber levels found in these systems are not unique when compared to levels observed elsewhere in North America.     

Development of information intensive agrichemical management services in wisconsin

This paper examines opportunities to improve the environmental and economic performance of cropping systems through intensified application of information in agrichemical management. Through intensified application of information, both net farm income and environmental quality may increase through more closely matching the specific needs of the crop with the type, timing, and volume of chemical inputs used in crop production. This study examines the current status and future prospect of agrichemical dealers offering information intensive agrichemical management services to producers. Agrichemical dealers are the focus of this study because: (1) farmers are perceived as ill-prepared to substantially upgrade the sophistication of their agrichemical management without off-farm support, and (2) dealers enjoy a close relationship with farmers, which potentially could be expanded to include a variety of information-based services. A mail survey was conducted of all agrichemical suppliers/applications in Wisconsin. The response rate was 76% (172 of 225). Substantial numbers of services were found to be offered by many dealers. The majority of these services were related to traditional yield-enhancement function. Services that have a greater potential to mitigate the negative environmental impacts of inefficient agrichemical use and have higher on-farm data requirements were found to be less widely offered by dealers. Analysis of constraints to further development of information-intensive services indicates that dealers offering significant numbers of services are concerned with constraints external to the dealership, while dealers offering relatively few services perceive internal constraints as most limiting. This relationship indicates that efforts to accelerate dealerships' development of information-intensive agrichemical management services should focus on specific constraints operating on targeted dealerships.     

汕头市地震灾害评估方案

本文根据汕头市城市现状,提出了汕头市地震灾害评估方案。包括利用GIS建立地区小区划数据库,房屋基本数据库,生命线系统基本数据库,基本图形数据库,地震灾害评估知识库和地震灾害评估决策系统。     

重大危险源企业级应急救援信息系统的研究

以某大型危险化学品储运企业为背景,对重大危险源应急救援信息系统进行研究,首先对重大危险源应急救援过程中各种信息需求进行分析,将信息分为基础信息、预防信息和救援信息3个方面;然后在单机和网络两种版本硬件结构比较的基础上,以工艺参数传感器、泄漏传感器、火灾报警器、应急设备控制器等主要设备为基础构建了单机版的硬件结构;最后,采用C/S软件结构,运用组件式GIS技术,从系统的总体结构、数据库结构以及功能设计等几个方面对应急救援信息系统进行了研究。     

Modeling Stream Channel Characteristics From Drainage‐Enforced DEMs in Puget Sound,Washington, USA1

Abstract: Mapping stream channels and their geomorphic attributes is an important step in many watershed research and management projects. Often insufficient field data exist to map hydromorphologic attributes across entire drainage basins, necessitating the application of hydrologic modeling tools to digital elevation models (DEMs) via a geographic information system (GIS). In this article, we demonstrate methods for deriving synthetic stream networks via GIS across large and diverse basins using drainage‐enforced DEMs, along with techniques for estimating channel widths and gradient on the reach scale. The two‐step drainage enforcement method we used produced synthetic stream networks that displayed a high degree of positional accuracy relative to the input streams. The accuracies of our estimated channel parameters were assessed with field data, and predictions of bankfull width, wetted width and gradient were strongly correlated with measured values (r² = 0.92, r² = 0.95, r² = 0.88, respectively). Classification accuracies of binned channel attributes were also high. Our methodology allows for the relatively rapid mapping of stream channels and associated morphological attributes across large geographic areas. Although initially developed to provide salmon recovery planners with important salmon habitat information, we suggest these methodologies are relevant to a variety of research and management questions.     

基于可缩放矢量图形(SVG)的应急救援网络地理信息系统(WebGIS)构建

地理信息系统(GIS)平台采购成本高、信息发布缺乏有效通用方法,使利用其进行二次开发的模式难以符合一些应急救援信息系统建设实际需要。万维网联盟制定的可缩放矢量图形(SVG)为解决这些问题提供了契机。在评价SVG作为下一代网络矢量图形开放标准的优势基础上,对如何以SVG为基础构建应急救援网络地理信息系统(WebGIS)进行了深入分析;介绍了用SVG设计应急救援专题电子地图的特色与实现方法,然后针对该专题对基于SVG的WebGIS架构进行了剖析与优化设计,并引入了重大危险源元数据库与应急救援方法库两个概念,最后给出一个重大危险源应急救援信息系统的框架。以该技术建立的应急救援WebGIS无平台依赖性,网络发布与交互便捷,开发具有伸缩性,适合不同层次应用需求。     

中国地震灾害现状及地震灾害系统工程研究

本文在对中国地震灾害现状分析的基础之上，依据地震工作三大体系的要求和建设首都圈防震减灾系统工程的经验，提出了在我国建立地震灾害系统工程的设想，并对该系统进行了初步的设计和论证。分析研究表明，地震灾害系统工程可以涵盖地震工作的各个方面，并且具有系统化、法制化及高科技等特点，对我国实现减轻地震灾害的目标具有积极的推进作用。     

Decision support systems for major accident prevention in the chemical process industry: A developers’ survey

Solid major accident prevention management is characterized by efficient and effective risk assessments. As a means of addressing the efficiency aspect, decision support analysis software is becoming increasingly available. This paper discusses the results of a survey of decision support tools for investigating (internal and external) major hazards in the chemical industry. The most significant features, such as the usability and the functionality of the toolkits are discussed. Toolkit characteristics are analyzed in the light of the different major risk decision process stages. Consequently, valuable supportive information for company decision makers purchasing such software is given. Furthermore, conclusions are drawn and recommendations are formulated for establishing priorities for future risk toolkits developments.     

COMBINED SURFACE WATER-GROUNDWATER ANALYSIS OF HYDROLOGICAL SYSTEMS WITH THE AID OF THE HYBRID COMPUTER1

The solution with the aid of the hybrid computer of the partial and total differential equations for an integrated surface water groundwater system is described. A versatile computing technique has been developed to make a rapid and accurate study of the groundwater response due to varying inputs (deep percolation) or outputs (evapotranspiration) from the groundwater system. Spatial variations in basic vegetation phenomena, such as pattern, and hydrological parameters, are represented by means of a grid network which also allows the input of variable boundary conditions. The model is applied to an area in Columbia, South America which is subject to high water-table conditions. Various reclamation schemes and management practices under conditions of irrigated agriculture are assessed.