IMPERVIOUSNESS: A PERFORMANCE MEASURE OF A DELAWARE WATER RESOURCE PROTECTION AREA ORDINANCE1

ABSTRACT: The New Castle County Resource Protection Area Technical Advisory Committee (RPATAC) requested that the University of Delaware utilize impervious cover estimates to evaluate the performance of the Water Resource Protection Area (WRPA) ordinance. This 1991 ordinance was the first in Delaware to protect the quantity and quality of drinking water supplies by limiting new development in WRPAs ‐ such as areas of ground water recharge, wellhead protection, drainage above reservoirs (reservoir watersheds), and limestone aquifers ‐ to a maximum 20 percent impervious cover. The research used geographic information system (GIS) techniques to evaluate the effectiveness of the ordinance in attaining its objective. The analysis indicated that 138 new developments were proposed in WRPAs since the ordinance was approved in 1991. The composite impervious cover of the 231 square kilometers of WRPAs in New Castle County is 15 percent, less than the 20 percent code requirement, ranging from 7 percent in recharge areas to 41 percent in several wellhead protection areas. To further protect drinking water supplies, the study results indicate, New Castle County should discourage code variances for applications in the more developed WRPAs, those where impervious cover already exceeds 20 percent, and should acquire parks and open space to protect the healthier WRPAs where impervious cover is currently less than 20 percent.     

THE DEVELOPMENT AND IMPLEMENTATION OF A GIS-BASED CONTAMINANT SOURCE INVENTORY OVER THE SPOKANE AQUIFER,SPOKANE COUNTY WASHINGTON1

ABSTRACT: U.S. Environmental Protection Agency (EPA) statutes require identification of all potential sources of contamination within a wellhead protection area. All wells over Spokane County's aquifer are included in one wellhead protection zone called the Aquifer Sensitive Area (ASA). A GIS-based Contaminant Source Inventory (CSI) was developed for the ASA. Datasets listing businesses and agencies within the ASA were imported into the GIS from state, county, city, and local agencies. These datasets were selected, joined, and sorted using GIS relational database capabilities into one ASA “business master file.” Map files were projected and transformed into common coordinates. Next, business sites within the master file were spatially related by address to the digital map files. Likely Critical Materials Users (CMU) were identified by sorting on selected standard Industrial Codes (SIC). Additional files of CMUs were imported into the Contaminant Source Inventory. GIS queries were performed to locate specific materials, quantities, and storage facilities, and to analyze CMU activity within selected buffer zones. This project demonstrated the usefulness of GIS technology in the development, management, maintenance, and analysis of vast quantities of data associated with a local wellhead protection pro. gram.     

Geographic information systems: a tool for strategic ground water quality management

Geographically‐related information is needed for several elements of an integrated ground water quality management programme, including ground water monitoring planning, prioritization of pollution sources, usage of permits and inspections for source control, and planning and completion of remedial actions. Geographic Information Systems (GISs) can be used to support these elements along with delineating wellhead protection areas (WHPAs), prioritizing existing contaminant sources and evaluating proposed changes in land usage in such areas. Eight case studies of the use of GISs in wellhead protection programmes are summarized, including examples from Rhode Island, Mississippi, New Jersey, New York, Pennsylvania, Kansas, Massachusetts and Texas. Six additional examples are mentioned relative to the use of GISs for evaluating ground water pollution potential, facilitating data analysis for environmental restoration of a large area with numerous waste sites, evaluating trends in ground water nitrate contamination, establishing a national database for ground water vulnerability to agricultural chemicals, simulating water table altitudes from stream and drainage basin locations, and selecting radioactive waste dump sites. The applicability of GISs and their associated advantages in wellhead protection and other ground water management studies are demonstrated via the case studies. The GIS technology provides a unique opportunity for analysing and visualizing spatial data. Contaminant and source prioritization within WHPAs is needed for both extant conditions and in the evaluation of proposed land use changes. The coupling of a GIS with contaminant/source prioritization would provide a strategic tool which could be used to plan targeted ground water monitoring programmes, to identify appropriate management or mitigation measures, minimize introduction of contaminants from existing sources into the subsurface environment, and to evaluate the potential of proposed land use activities for causing ground water contamination. GISs can be useful in providing current information for policy makers, planners and managers engaged in ground water quality decision making.     

METHODOLOGY OF DELINEATING WELLHEAD PROTECTION ZONES IN CRYSTALLINE BEDROCK IN MAINE1

ABSTRACT: Delineation of contributing areas for wellhead protection around supply wells drilled into bedrock in Maine, USA, is currently achieved by assigning a fixed radius circle around the well. This project develops a methodology that incorporates hydrogeologic processes and ground water modeling (MODFLOW) and accounts for variable data availability to estimate the areas that contribute water to 26 bedrock supply wells. Outcrop fracture mapping and lineament analysis are used to characterize the fracture system. Multiple simulations are constructed of each site using ranges of values for recharge, hydraulic conductivity, and anisotropy. Uncertainty in the delineation process is accounted for by portraying the delineated areas as confidence zones that are constructed by overlapping the capture zones from the multiple simulations. The results are variable and depend on the ability to characterize a site in a way that can be easily modeled. Sites with complex hydrogeology tend to have larger contributing areas that reflect the greater uncertainty in the parameters. The majority of the sites, however, produce reasonable results that provide a much more accurate depiction of the area likely to contribute to a bedrock well than the fixed radius circle.     

GIS在水污染控制中的研究与探讨

地理信息系统(GIS)是专门用于地理空间信息处理和管理的计算机技术系统，造成城市水污染的污染源及其相关数据均具有空间分布特性，这决定了GIS可在该领域发挥重要作用。GIS能支持与水环境有关的地理空间数据的获取、管理、分析、模拟和显示，以解决复杂的水环境综合治理问题和水污染控制问题；同时，建立完善的空间数据库和属性数据库，为环境保护部门和科研部门提供研究与决策支持。本文就GIS在水污染控制这一领域的应用做一定探讨。     

MAXIMIZING THE VALUE OF INFORMATION FOR GROUND WATER PROTECTION: THREE TEST CASES1

ABSTRACT: Public awareness of the importance of protecting the nation's water supplies is growing. Recent studies have shown a substantial increase in the perceived value of protecting water supplies for future use. In the Northeast, much of the water supply comes from ground water. This paper examines three test cases, each with different approaches for using geographic information systems (GIS) for ground water protection planning. In Wellfleet, Massachusetts, build-out scenarios were used to support regulatory and land acquisition decisions for siting a public water supply well. In Hadley, Massachusetts, the focus was on a decision support model for septic suitability assessment in support of regulatory efforts and infrastructure expansion. For Cortland County, New York, an interactive graphic user interface was created to facilitate the manipulation and recombination of a large volume of data by county officials to target ground water pollution prevention efforts. As personal computers become more powerful and inexpensive, and GIS data become more readily available, community and county governments are turning to GIS as a tool for developing comprehensive resource protection plans. Once appropriate data are input, a GIS can effectively and efficiently be used to derive outcomes of various land use plans and regulations.     

A GIS-based decision support system for regional eco-security assessment and its application on the Tibetan Plateau

Regional eco-security assessment is an intricate, challenging task. In previous studies, the integration of eco-environmental models and geographical information systems (GIS) usually takes two approaches: loose coupling and tight coupling. However, the present study used a full coupling approach to develop a GIS-based regional eco-security assessment decision support system (ESDSS). This was achieved by merging the pressure-state-response (PSR) model and the analytic hierarchy process (AHP) into ArcGIS 9 as a dynamic link library (DLL) using ArcObjects in ArcGIS and Visual Basic for Applications. Such an approach makes it easy to capitalize on the GIS visualization and spatial analysis functions, thereby significantly supporting the dynamic estimation of regional eco-security. A case study is presented for the Tibetan Plateau, known as the world’s “third pole” after the Arctic and Antarctic. Results verified the usefulness and feasibility of the developed method. As a useful tool, the ESDSS can also help local managers to make scientifically-based and effective decisions about Tibetan eco-environmental protection and land use.     

GEOGRAPHIC INFORMATION SYSTEMS AS A TOOL IN WATER USE DATA MANAGEMENT1

ABSTRACT: The temporal and locational attributes of water use data are ideally suited for analysis using a geographic information system (GIS) approach. A GIS combines spatial database management, statistical analysis, and cartographic modelling capabilities within a computer hardware and software configuration. Texas water use data for selected categories in 1980 and 1986 were analyzed using ARC/INFO to demonstrate the utility of GIS for water resource information management. Examples of data analysis and display are presented to illustrate the effectiveness of cartographic representations to communicate water use data.     

SPATIAL MODELLING WITH GEOGRAPHIC INFORMATION SYSTEMS FOR DETERMINATION OF WATER RESOURCES VULNERABILITY APPLICATION TO AN AREA IN MASSIF CENTRAL (FRANCE)1

ABSTRACT: A method for water resources protection based on spatial variability of vulnerability is proposed. The vulnerability of a water resource is defined as the risk that the resource will become contaminated if a pollutant is placed on the surface at one point as compared to another. A spatial modelling method is defined in this paper to estimate a travel time between any point of a catchment and a resource (river or well). This method is based on spatial analysis tools integrated in Geographical Information Systems (GIS). The method is illustrated by an application to an area of Massif Central (France) where three different types of flow appear: surface flow, shallow subsurface flow, and permanent ground water flow (baseflow). The proposed method gives results similar to classical methods of estimation of travel time. The contribution of GIS is to improve the mapping of vulnerability by taking the spatial variability of physical phenomena into account.     

INTERFACING GIS WITH WATER RESOURCE MODELS: A STATE‐OF‐THE‐ART REVIEW1

Two distinctive, independently developed technologies, geographic information systems (GIS) and predictive water resource models, are being interfaced with varying degrees of sophistication in efforts to simultaneously examine spatial and temporal phenomena. Neither technology was initially developed to interact with the other, and as a result, multiple approaches to interface GIS with water resource models exist. Additionally, continued model enhancements and the development of graphical user interfaces (GUIs) have encouraged the development of application “suites” for evaluation and visualization of engineering problems. Currently, disparities in spatial scales, data accessibility, modeling software preferences, and computer resources availability prevent application of a universal interfacing approach. This paper provides a state‐of‐the‐art critical review of current trends in interfacing GIS with predictive water resource models. Emphasis is placed on discussing limitations to efficient interfacing and potential future directions, including recommendations for overcoming many current challenges.     

DEVELOPMENT OF A WATER SUPPLY PROTECTION MODEL IN A GIS1

ABSTRACT: As part of a larger model to identify lands suitable for acquisition, a water supply protection model was developed using the Southwest Florida Water Management District's GIS. Several hydrologic and hydrogeologic data layers were overlaid to develop maps showing ground-water supply suitability, protection areas for surface-water supply, protection areas for major public supply wells, susceptibility to ground-water contamination, and recharge to the Floridan aquifer. These intermediate layers were combined into a final map to prioritize protection areas for water supply.     

An approach for delineating drinking water wellhead protection areas at the Nile Delta, Egypt

In Egypt, production has a high priority. To this end protecting the quality of the groundwater, specifically when used for drinking water, and delineating protection areas around the drinking water wellheads for strict landuse restrictions is essential. The delineation methods are numerous; nonetheless, the uniqueness of the hydrogeological, institutional as well as social conditions in the Nile Delta region dictate a customized approach. The analysis of the hydrological conditions and land ownership at the Nile Delta indicates the need for an accurate methodology. On the other hand, attempting to calculate the wellhead protected areas around each of the drinking wells (more than 1500) requires data, human resources, and time that exceed the capabilities of the groundwater management agency. Accordingly, a combination of two methods (simplified variable shapes and numerical modeling) was adopted. Sensitivity analyses carried out using hypothetical modeling conditions have identified the pumping rate, clay thickness, hydraulic gradient, vertical conductivity of the clay, and the hydraulic conductivity as the most significant parameters in determining the dimensions of the wellhead protection areas (WHPAs). Tables of sets of WHPAs dimensions were calculated using synthetic modeling conditions representing the most common ranges of the significant parameters. Specific WHPA dimensions can be calculated by interpolation, utilizing the produced tables along with the operational and hydrogeological conditions for the well under consideration. In order to simplify the interpolation of the appropriate dimensions of the WHPAs from the calculated tables, an interactive computer program was written. The program accepts the real time data of the significant parameters as its input, and gives the appropriate WHPAs dimensions as its output.     

基于GIS的自然保护区管理信息系统建设

探讨了GIS在自然保护区建设与管理中的应用,以及利用最新的组件式GIS技术开发适合保护区的管理信息系统.结合GIS的信息管理模式比传统的信息管理更能实时地表现空间数据,提高了自然保护区的科研与工作效率.介绍了自然保护区信息管理系统的设计原则、开发方式、总体构架、数据库及其主要功能.     

Conceptual Design of a System for Selecting Appropriate Groundwater Models in Groundwater Protection Programs

/ An effective groundwater protection program requires understanding of water flow and contaminant transport processes in the subsurface. Although many mathematical models have been developed to simulate the processes, few actually are used in groundwater protection programs due to the difficulties in data collection, model selection, and model implementation. This study presents a conceptual design of a GIS-supported model selection system that evaluates available data and mathematical models to facilitate groundwater protection programs. Steady-state groundwater and contaminant transport models applied in isotropic aquifers are placed into four classes to simulate conservative or nonconservative contaminant transports in simple or complex geohydrological conditions. After analyzing specific study objectives, available data, and model requirements, the proposed system selects a class of models that can be used in simulation and recommends any need for additional data collection. This study initiates an effort to integrate GIS, mathematical models, and expert knowledge in one system to promote the application of appropriate groundwater models. The new technology of GIS and digital data-base management makes it possible to develop such a system in practice.KEY WORDS: Groundwater models; Geographic information systems     

VALIDATION OF AGNPS FOR SMALL WATERSHEDS USING AN INTEGRATED AGNPS/GIS SYSTEM1

ABSTRACT: The AGNPS (AGricultural NonPoint Source) model was evaluated for predicting runoff and sediment delivery from small watersheds of mild topography. Fifty sediment yield events were monitored from two watersheds and five nested subwater-sheds in East Central Illinois throughout the growing season of four years. Half of these events were used to calibrate parameters in the AGNPS model. Average calibrated parameters were used as input for the remaining events to obtain runoff and sediment yield data. These data were used to evaluate the suitability of the AGNPS model for predicting runoff and sediment yield from small, mild-sloped watersheds. An integrated AGNPS/GIS system was used to efficiently create the large number of data input changes necessary to this study. This system is one where the AGNPS model was integrated with the GRASS (Geographic Resources Analysis Support System) GIS (Geographical Information System) to develop a decision support tool to assist with management of runoff and erosion from agricultural watersheds. The integrated system assists with the development of input GIS layers to AGNPS, running the model, and interpretation of the results.     

LOS ALAMOS FOREST FIRE IMPACT MODELING1

ABSTRACT: A controlled burn at Bandelier National Monument got out of control and burned about 43,000 acres (17,400 hectares) near Los Alamos, New Mexico, in May 2000. The wildfire caused dramatic changes in infiltration capacity and wettability of soils in many of the watersheds above Los Alamos National Laboratory (LANL) and destroyed the duff layer, dramatically reducing the interception and infiltration capacity of the formerly forested watersheds. These sudden changes in basin hydrology necessitated a rapid assessment of hydrology and hydraulics for the canyons running through LANL property to evaluate flood risk, plan emergency flood protection measures, and assess potential sediment and actinide transport. This paper presents the results of hydrologic and hydraulic modeling of Los Alamos Canyon following the wildfire. The large scale modeling effort, with over 13,000 cross sections for the hydraulic model (5,000 for Los Alamos Canyon, 8,000 for Guaje Canyon), relied heavily on a geographic information system (GIS) for model input and floodplain delineation. The HEC‐geoRAS model provided good integration between the hydraulic model (HEC‐RAS, Version 3.0.1) and the GIS (ArcView, v. 3.3). These modeling results are being used in drainage master planning efforts at LANL and in the development of sediment transport models using HEC‐6T. Sediment transport modeling results will be used to develop actinide transport models for the canyons at LANL.     

Statistical evidence on the effectiveness of sewering to protect groundwater from VOC contamination

Volatile organic compounds (VOCs) are an important source of contamination of groundwater supplies in Massachusetts and many parts of the United States. One local response is to require sewering in wellhead protection areas as an easily enforceable policy designed to reduce the probability of VOC contamination of groundwater. Data were collected for 238 wellhead protection areas in Massachusetts on VOC contamination levels and the sewered and unsewered land uses in those aquifer recharge areas. Logistic regression procedures were used to see whether sewering had any statistical effect on likelihood of contamination of well water. The results provided limited, but not overpowering, support for the idea that requiring commercial and industrial land uses to use sewers would reduce the chance of VOC contamination.     

Linking GIS-based models to value ecosystem services in an Alpine region

Planning frequently fails to include the valuation of public goods and services. This can have long-term negative economic consequences for a region. This is especially the case in mountainous regions such as the Alps, which depend on tourism and where land-use changes can negatively impact key ecosystem services and hence the economy. In this study, we develop a semi-automatic procedure to value ecosystem goods and services. Several existing process-based models linked to economic valuation methods are integrated into a geographic information system (GIS) platform. The model requires the input of a digital elevation model, a land-cover map, and a spatially explicit temperature dataset. These datasets are available for most regions in Europe. We illustrate the approach by valuing four ecosystem services: avalanche protection, timber production, scenic beauty, and habitat, which are supplied by the “Landschaft Davos”, an administrative district in the Swiss Alps. We compare the impacts of a human development scenario and a climate scenario on the value of these ecosystem services. Urban expansion and tourist infrastructure developments have a negative impact on scenic beauty and habitats. These impacts outweigh the benefits of the developments in the long-term. Forest expansion, predictable under a climate change scenario, favours natural avalanche protection and habitats. In general, such non-marketed benefits provided by the case-study region more than compensate for the costs of forest maintenance. Finally, we discuss the advantages and disadvantages of the approach. Despite its limitations, we show how this approach could well help decision-makers balance the impacts of different planning options on the economic accounting of a region, and guide them in selecting sustainable and economically feasible development strategies.     

Urbanization and its impact on groundwater: a remote sensing and GIS-based assessment approach

The perils of unplanned urbanization and increasing pressure of human activities on hydro-geomorphologic system often result in modification of the existing recharge mechanism, which leads to many environmental consequences. In the present research, an attempt has been made to investigate the applicability of remote sensing and geographical information system (GIS) in dealing with spatial and temporal variability of dynamic phenomena, like urbanization and its impact on groundwater. This paper covers primarily, quantitative and qualitative impacts of urban growth on the behavior of aquifer in Ajmer city (India). Urban growth of the Ajmer city in last 17 years has been estimated from the satellite images. Database related to urbanization and groundwater has been created in GIS. Groundwater recharge has been computed using a water balance approach known as Water Level Fluctuation Methodology. Recharge estimation methodology has been implemented in GIS to introduce the spatial variability of hydro-geological characteristics. Further, temporal and spatial variations in groundwater quality and quantity have been correlated with urban growth using overlay analysis in GIS. The study reveals a general decline in water table and quality with urbanization. Further, remote sensing and GIS technologies have been found useful in assessment of spatial and temporal phenomena of urbanization and its impact on groundwater system.     

Agricultural Land Use and Best Management Practices to Control Nonpoint Water Pollution

In recent years, improvements in point-source depuration technologies have highlighted the problems regarding agricultural nonpoint (diffuse) sources, and this issue has become highly relevant from the environmental point of view. The considerable extension of the areas responsible for this kind of pollution, together with the scarcity of funds available to local managers, make minimizing the impacts of nonpoint sources on a whole basin a virtually impossible task. This article presents the results of a study intended to pinpoint those agricultural areas, within a basin, that contribute most to water pollution, so that operations aimed at preventing and/or reducing this kind of pollution can be focused on them. With this aim, an innovative approach is presented that integrates a field-scale management model, a simple regression model, and a geographic information system (GIS). The Lake Vico basin, where recent studies highlighted a considerable increase in the trophic state, mainly caused by phosphorus (P) compounds deriving principally from the intensive cultivation of hazelnut trees in the lake basin, was chosen as the study site. Using the management model Groundwater Loading Effects of Agricultural Management Systems (GLEAMS), the consequences, in terms of sediment yield and phosphorus export, of hazelnut tree cultivation were estimated on different areas of the basin with and without the application of a best management practice (BMP) that consists of growing meadow under the trees. The GLEAMS results were successively extended to basin scale thanks to the application of a purposely designed regression model and of a GIS. The main conclusions can be summarized as follows: The effectiveness of the above-mentioned BMP is always greater for erosion reduction than for particulate P reduction, whatever the slope value considered; moreover, the effectiveness with reference to both particulate P and sediment yield production decreases as the slope increases. The proposed approach, being completely distributed, represents a considerable step ahead compared to the semidistributed or lumped approaches, which are traditionally employed in research into tools to support the decision-making process for land-use planning aimed at water pollution control.