A Decision Support System of Animated Graphs, GIS, and Temporal Ecological Data to Quantify and Disseminate Water Quality Information
Joanne N. Halls Department of Earth Sciences, University of North Carolina, 601 South College Road, Wilmington, North Carolina, USA, 28403-3297,
[email protected] Keywords:
interactive mapping, GIS, decision support system, dynamic visualization, water quality
Abstract:
To visualize the water quality of the Lower Cape Fear River basin a Decision Support System (DSS) web site was developed which incorporates dynamic graphing and Geographic Information System (GIS) software. Together, these two software packages enable users to interact with water quality variables in order to investigate the spatial and temporal complexity of the data. The result of this research is that graphing and GIS technology are capable of being implemented over the Internet and that complex water quality data can be successfully disseminated using this medium. However, there is a need to seamlessly link the graphing and GIS software which will make the visualization tools much more successful at communicating the complex spatial and temporal data. Future research will seamlessly integrate these software tools, provide more advanced a analysis, and allow users to learn about coastal river ecology using interactive tools.
1
INTRODUCTION
Urban planning, sustainable growth, and ecosystem management are separate disciplines and yet geography is the underlying framework that links these land use decisions. A Geographic Information System (GIS) is a software toolbox for integrating disparate spatial data, analyzing and modeling spatial and attribute relationships, and producing a variety of outputs, most notably maps, for disseminating information. There are several definitions of GIS but one often cited is “a set of tools for collecting, storing, retrieving at will, transforming, and displaying spatial data from the real world for a particular set of purposes” (Burrough, 1986, 6). Only recently have the results of years of data collection been readily available to the public due to the rapid commercialization of the Internet. This paper describes the development of a web site designed for graphically and spatially disseminating water quality information for the Lower Cape Fear River. Whereas Decision Support Systems (DSS) and Spatial DSSs (SDSS) have traditionally been implemented within an organization, the network expansion of Internet access and growth in technologies geared towards information dissemination have made it possible to develop DSSs and SDSSs for the Internet. In the future, technological advances could enable fully functional GIS applications, including spatial analysis, to be implemented over the Internet (Foresman, 1999). One example of making strides towards on-line
spatial analysis is demonstrated by this research which successfully created simultaneously interactive mapping and dynamic temporal graphing. 2
ENVIRONMENTAL DSS AND THE INTERNET
The Internet’s World Wide Web (WWW) is becoming a primary means of disseminating information. The traditional method for obtaining GIS data across the Internet was downloading data by ftp’ing the data and saving the compressed files on your personal hard disk space. Recently, the U.S. Federal Geographic Data Committee (FGDC) developed a metadata standard for documenting the source(s), appropriate use(s), scale, and many other important characteristics of spatial database (see http://www.fgdc.gov/ ). Although labor intensive to create, the metadata report has vastly improved the information content available to potential users of GIS data. However, it is still often difficult to determine the usefulness of data because a potential user cannot interact and visualize the data. Therefore, GIS users are continuing to download, uncompress, convert, and import these data into a GIS in order to determine the usefulness of these data for their particular application. With the advent of producing maps over the Internet, GIS users and developers can now see the spatial characteristics of the data instantly and then decide the degree of appropriateness of the data for their application. The ability to host maps over the Internet has created an environment for professionals to see the GIS data before going through the lengthy process of converting data into a useable format. In contrast to static Internet mapping, interactive mapping is growing as a mechanism for users to investigate data and perform spatial visualization analysis. This technology uses the Internet client-server scenario where the user (client) submits commands, the web server processes the commands, and a result is passed to the client in the form of an updated map in a Web browser window. For non-GIS users, the ability of the public to interact with maps over the Internet has allowed for information dissemination at the local level where more of the population can see various data layers of interest to where they live and work. In fact, the Internet has evolved into such an important information source that it has quickly become a leading factor in the development of GIS technology (Thoen, 1999). This is a new medium for GIS scientists. In 1993 the U.S. government published a report (OMB Circular A-130) that established a policy for information exchange and distribution. In 1994 the U.S. government developed the National Spatial Data Infrastructure (Executive Order 12906) which made coordinating federal spatial data a priority and led to the development of the Federal Geographic Data Committee. This committee has spearheaded the development of an Internet-based clearinghouse network based on a database designed metadata format for documenting spatial data. Up until this point GIS users were UNIX based researchers, but in 1995 Microsoft Windows 95 was released and this gave GIS software vendors a PC platform that was more robust and easier to network. Soon all major vendors were supporting the 32-bit PC platform for desktop mapping, but not GIS. At this point, the GIS industry was beginning to develop methods of displaying map data across Wide Area and Local Area networks. In 1996, tools for hosting web-enabled maps over the Internet were becoming available for GIS developers as a means of displaying information. Currently the ability exists to create interactive maps over the Internet using a client-server network technology and special mapping software.
Over the last two decades GIS has grown at such a rapid rate so that virtually all surfaces of the United States have digital maps and most urban planning offices have GIS implementations complete with data for every parcel of land. Geographers have utilized GIS for analyzing urban growth scenarios and researchers have shown that GIS visualization tools for interacting with GIS data are viable over the Internet (El-Raey, Fouda, and Gal, 2000; Huang and Lin, 1999). This technology has allowed for an increasing number of people to visualize spatial GIS data. However, there has not been a method of displaying GIS data that has a large temporal dimension or is interactive where users can change the information displayed on the map. In the environmental realm, Internet mapping has not been developed as a means of synthesizing and visualizing numerous parameters over space and time. Focus has been on developing 3-D visualization techniques where the user can see one point in time and what the study area looks like. This paper explores the development of a non-static GIS-enabled web environment where both interactive mapping and data streaming graphics give users the ability to explore water quality data to understand the complex nature of this hydrological environment. Data streaming is a method of dynamically visualizing the characteristics of data. Internet software structure using java programming has given the user the ability to independently interact with data across the network. 3
CASE STUDY: THE LOWER CAPE FEAR RIVER BASIN 3.1 Environmental Threats
The coastal zone of North Carolina has numerous environmental issues some of which include coastal hazards such as erosion, hurricane disaster impacts, flooding, emergency management, drinking water resources, and many other catastrophic impacts. Recent hurricanes have had widespread catastrophic impacts along coastal North Carolina and most recently with the large flooding and resulting water pollution from Hurricane Floyd (Bowie, 2000; Environmental News, 2000; Zagier 2000). From a longterm, non-disaster perspective, there are many recently recognized environmental concerns regarding the balance of human development and ecosystem health. New Hanover County, a small county located in Southeastern North Carolina, has experienced rapid population growth in a region consisting of (but not limited to) various types of wetlands, pristine and developed barrier islands, salt marshes, shallow groundwater table, critical fisheries and shellfish resources, and tidally influenced complex hydrologic network. The rapid population growth has led to an increase in suburban development that has resulted in ecosystem loss due to urban encroachment and conversion of agricultural lands to urban lands consisting of mostly single-family residential gated communities, strip malls, and new transportation corridors. This urban development scenario is typical of most cities in the United States; however this area is also profoundly affected by the relatively recent growth in industrial hog farming throughout the Piedmont and coastal regions of North Carolina. Recent events have documented the spraying of hog waste on river floodplains and lagoon failure where effluents have reached rivers (Mallin, 2000). These environmental threats have led to increased biological, ecological, and public safety monitoring programs in the region. It is hoped that research such as this will lead to more public awareness of our natural resources by
providing access to the data over the Internet in a manner which is user friendly, comprehensive, and unbiased. 3.2 Development of River Run There are several approaches for managing environmental problems in urban areas and although many local governments have current GIS technology, the data can be out-dated and the mechanism for involving the community and is inclusive of all residents due to the inability to successfully inform the public/community of (IyerRaniga and Treloar, 1999). In urban planning, GIS technology has been embraced as “a way to monitor the overall environment, as a tool to analyse planning options, as a guide to reduce risk for the decision maker and as a set of techniques to assist those who might implement the decisions” (Dale, 1991, p. 14). The current environmental emphasis is in integrated analysis and integrated ecosystem management (Swaminathan, 1999). Towards this end, integrated assessment has led to many recent advances in modeling and managing resources using the natural geographic area of watersheds (Voinov and Costanza, 1999; He, Malcolm, Dahlberg, and Fu, 2000). The use of watersheds as the geographic framework for developing GIS applications has led to integrated spatial analysis and process modeling. In February 2000 a project was initiated to develop a web site for visualization of water quality sampling data along the Lower Cape Fear River basin (Figure 1). The River Run website (www.uncwil.edu/riverrun) was developed for educators, university scientists, environmental regulators and the general public for environmental information dissemination. Therefore, the scientific premise for developing the River Run web site is the devlopement of an Environmental Decision Support System (E-DSS). By definition, an E-DSS is an “information system containing at least one component whose purpose is to support human decision making about an environmental issue” (Swayne, et al. 1999, p. 260). The River Run website is an excellent teaching tool which sparks the intellectual curiosity and imagination of its users. It is particularly appropriate for undergraduate limnology and environmental studies students. Using this website enhances students' understanding of the interaction of seasonal variations on environmental indicators. The River Run website is highly interactive and is designed to stimulate creative inquiry. The website provides public Internet access to the information gathered by the Lower Cape Fear River Program, which is one mission of the Program. Stakeholders of the lower Cape Fear benefit by using this web site to gather information about the local quality of water for many environmental variables. Unlike public forum meetings where the public is presented with mapped information that summarizes information and can be misleading, the dissemination of information over the Internet using tools that allow the public to interact with the raw data empowers the users to question the spatial and temporal distribution of the data. River Run provides a local and regional service by providing interactive and exciting Internet access to the water quality data. The information helps those in this watershed to understand the processes of the river and the impacts on it. This knowledge empowers the users to better protect the quality of life and the environment in our coastal region.
3.3 Interactive Mapping Previous research has shown that existing technology can implement some GIS tools over the Internet (Keskisarja and Sirvio, 1999). However, the ability to illustrate highly temporal data and spatially complex information has been implemented on the River Run site using both GIS and dynamic graphing for visualizing multivariate relationships. The River Run site contains an interactive GIS mapping tool that displays water quality parameters in the lower Cape Fear basin. The Internet Map Server (IMS), a product of ESRI, is located in the UNCW Department of Earth Sciences Spatial Analysis Lab (gisweb.uncwil.edu) and provides the user with a map interface to the water quality data. There is a separate map interface for a base map for the user to get familiar with the area and each water quality parameter: dissolved oxygen, fecal coliform, temperature, total nitrogen, and total phosphorus (Figures 1, 2, 3). The User can turn on and off data layers and the IMS responds to the selections by updating the map. The maps are not all stored in the SAL server, but are generating dynamically as the user interacts with the map interface on their browser. The user can also zoom in and out of the map, print maps, and select features on the map and list the attributes of those features. This interactive capability is a very power data dissemination and map visualization tool.
Figure 1. The distribution of the water quality base map information in the Lower Cape Fear River. Notice the locations of the sampling stations and the abundance of agricultural hog farms.
Figure 2. Spatial pattern of dissolved oxygen in October 1998. At this time of year the levels of dissolved oxygen are low due to a lack of rainfall.
Figure 3. Spatial pattern of dissolved oxygen in March 1999. At this time of year the levels of dissolved oxygen aremuch greater due to the high levels of rainfall typical for the Spring season.
3.4 Dynamic Graphing on The Web One of the strengths of the current River Run website is that it provides numerous opportunities for users to discover and explore extremely interesting ecological events, which tend to stand out when the data is graphically displayed. These provocative anomalies are abundant because the river systems from which the data are drawn have experienced numerous noteworthy events during the years over which the data were collected. Specifically, the River Run software tools provide data and utilities for exploring data on the water quality of the Cape Fear River and the Northeast Cape Fear River from 1995 to 2000. During these years these river systems experienced a major poultry farm spill, several ruptures of hog waste lagoons, five hurricanes, and a 500-year flood. Consequently, when water quality data are explored using the Data Visualization Tool conspicuous spikes in line graphs and flashes of color appear on the color mapper. These anomalies invite students to stop the animations, form hypotheses, reset parameters, and rerun the animations to test their hypotheses. For example, looking at the DVT default scenario for September 1998 at the NAV site, the effects of Hurricane Bonnie on four water quality parameters can be dramatically seen (Figure 4). The large spike in fecal coliform bacteria can be attributed to the shut down of the City of Wilmington's north side sewage treatment plant when the back-up power generators failed resulting in untreated human sewage being dumped directly into the Cape Fear River. Concurrently, the GIS mapping tool for September 1998 fecal coliform also spatially illustrates the surge in values at various locations in the basin (Figure 5). By resetting the parameters, students can easily determine the impact of Hurricane Bonnie on nine additional parameters at the NAV site or any of the other 15 sampling sites.
Figure 4. Effects of hurricane Bonnie on four water quality parameters.
Figure 5. Distribution of fecal coliform in September 1998. Notice the high value in New Hanover county that corresponds to the peak in the graph in Figure 4. Interpretations such as those made above could be further tested using the DVT and/or with other appropriate resources (such as newspaper records of flooding and storms). Regardless of the users take when exploring such anomalies, the animated color-coded graphics are an ideal tool for making the data come alive--the graphics leave no doubt about the fact that something interesting happened around the NAV testing station in September of 1998! 4
CONCLUSIONS
This paper explores the use of the Internet for visualizing complex spatial and temporal water quality data. Two methods were developed and implemented in order to test the usefulness and compatibility of data streaming via dynamic graphing and interactive GIS. The same databases were in both techniques where the graphs provided multiple variables and the rates of change over time at one station and the maps provided all stations through time for one variable. The power of the Internet for education and information dissemination lies in the ability of the user to interact directly with data in ways that foster inquiry. The River Run website (www.uncwil.edu/riverrun), offers powerful evidence that the Internet can stimulate inquiry. The data are currently very difficult to understand and although the individual pieces of software are working there is a need to make the two software tools seamlessly
linked, provide educational information about river ecology, and provide relevant summary maps and information to the public who do not have the time or need to sift through the raw data. All of the stakeholders of the lower Cape Fear will benefit by using this web site, especially if it provides meaningful information in a more user-friendly manner. Current research is being conducted to make these improvements and to test the visualization comprehension. Lastly, an environmental DSS for the Lower Cape Fear River should include a watershed model. There are many examples of successful watershed models and some of these at least partially use GIS for analyzing spatial data, recoding the data into a standardized attribute scheme, or presenting the results of an external model (Aspinall and Pearson, 2000; Ball, 1994; Chang, et al., 2000). One of the next developments to successfully implementing spatial analysis on the Internet will be the implementation of a true watershed model. It is very likely that a GIS will be used either by fully implementing a watershed model or loosely coupling the model to the web client through a map interface. 5
AKNOWLEDGEMENTS
This project was partially funded by a grant from the University of North Carolina at Wilmington’s Information Technology Innovations Award Committee. The collaborative efforts of several individuals were instrumental in the success of developing the River Run web site. The Lower Cape Fear River Program (Executive Director Marian McPhaul and Research Associate Dr. Michael Mallin) provided the water quality data and financial support for field data collection. The Students as Scientists Program (Dr. Richard Huber) initiated and managed the dynamic graphing software development. Steven Perry and Lori Speakman of the Information Technology Systems Division provided technical support for building the GIS web server. 6
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