Tim Foresman

Baltimore-Washington GIS Testbed for Regional and Global Change Research

ABSTRACT

Opponents to the theory of current and impending global change tend to overlook the definitive evidence of human impacts on the planet. Scientists and managers have recently begun focusing upon land transformation and urbanization processes using spatial technology tools to inventory, map, and model these human impacts. Their success to date has been hampered in part by the lack of universal standards to base their measurements or modeling results. Local or regional science-based resources, such as a database of validated reference materials to calibrate the performance of any single model, algorithm or procedure defining land transformation processes, have been missing. Therefore, a regional data center resource, of use to the community of environmental modelers and global change scientists in the form of georeferenced, spatially structured and well documented data sets, has been designed for the Baltimore-Washington Region.

Cooperative participation of scientists and land management personnel from federal, state, local, and university organizations is instrumental in building an Internet accessible "collaboratory" containing quality controlled, spatially referenced databases for applications requiring calibration and validation. Land transformation processes are being examined from a variety of perspectives and scales using numerous field data and remotely sensed measurements. This GIS testbed, known as the Baltimore-Washington Regional Collaboratory, provides for the calibration, verification, and validation of multiple scalar, temporal, thematic, and spectral studies or models. It is expected that regional and global change research can benefit from the GIS testbed as applied under various environmental modeling applications.

INTRODUCTION

Global change issues remain controversial, as the implications of redirecting or managing human activities becomes translated into business economics equations and land development politics. Many factors, reasoned to influence the acceleration of such global climate change variables, such as atmospheric greenhouse gases and global temperatures, have exhibited such incremental, daily rates of change that these obvious causal factors are often ignored. However, as the evidence for rates of global change related to human activities becomes more objectively evident the argument for or against global change research and policy concerns may switch to the citizenry at large and not held hostage by the special interests such as industrial-based financial organizations and energy corporations. Peter Vitousek (1994) describes, as well-documented factors of concern for global change community, the ongoing land use/land cover change, along with increasing concentrations of carbon dioxide in the atmosphere and alterations in the global nitrogen cycle.

A massive unplanned global experiment, known as urbanization, is affecting increasingly large acreages of the Earth's surface. This massive change in land surface character, a daily incremental event, is just beginning to be studied by Earth system scientists in terms of ecological processes, atmospheric implications and micro and macro-climatic impacts. McDonnell and Pickett (1990) have raised interesting questions regarding ecosystem structure and function along the urban-rural gradient, which may well translate to a host of global change concerns. New insights have been provided from recent investigations along the urban-rural gradient (Pouyat and McDonnell, 1991; et al., 1995) into the apparent impacts urbanization has introduced to stable ecological systems. Urbanization has been identified as a major causal agent for many topics of concern to scientists and citizens alike. These topics include issues that have considerable potential for influencing the quality of life such as:

Earth scientists appear to agree that urbanization is a key determinant in the litany of ecosystem transition processes of interest to the environmental modeling community. Some scientists are interested in furthering the study of these processes to include the human dimension of urbanization under a human ecosystems paradigm (Machlis et al,1996). At the global scale, interest in combining human and ecosystem models into the study of sustainable development has generated consensus regarding major categories for regional-global concern (Estes et al, 1994). However, a significant gap exists in the capabilities to address design and implementation of integrated modeling structures along the urban-rural gradient related to these concerns. Challenges of integrating and developing models to understand and predict processes of urbanization affecting social, economic, and environmental conditions require an interdisciplined approach. Collaboration of the human talents, modeling resources, and spatial data at local, regional, and global scales is required to meet these challenges. A collaborative spatial data testbed for the Baltimore-Washington region has been designed, referred to herein as the Baltimore-Washington Regional Collaboratory or simply Collaboratory to address these concerns. The framework and early results of the Collaboratory demonstrate significant potential for this partnership program to harness and focus many of the dispersed and uncoordinated local and regional activities to improve the understanding and management of our community resources.

Both the GIS and environmental modeling community remain interested in design and construction of large spatial databases for environmental modeling, as evidenced by the content of the three international conferences sponsored by the National Center for Geographic Information and Analysis. Progress has been made by members of the environmental modeling community in effectively employing entity-relationship-attribute schemas from GIS database structures. Object and feature-based schemas are described by many modelers as a successful path for improving performance of environmental models with respect to the ability to obtain data from spatial databases (Guptill, 1988; Raper and Livingston, 1995). Puequet (1994) offers an overview of temporal data structure theory that indicates various avenues of approach are available for time series analysis, requisite for change or trend analysis. Contemporary modeling with GIS remains, however, primarily focused on the application of time slices defining geographic entities either in raster or vector data structures (Kemp, 1993; Mitasova et al., 1995; Farmer and Rycoft, 1991). The Baltimore-Washington regional testbed is conservative in terms of its conventional GIS database development, with emphasis on improved metadata documentation. This approach offers better calibration opportunities to modelers using arc-node entity definitions and relational attribute definitions. Decisions and steps that led to the creation of the Baltimore-Washington regional testbed and the major activities for regional and global change research are outlined in this paper.

BACKGROUND

In partnership with the U.S. Geological Survey (USGS), the University of Maryland Baltimore County, under a grant from the National Aeronautics and Space Administration (NASA) Office of Mission to Planet Earth, has compiled historic maps, demographic data, environmental parameters, and satellite images to map human-induced land transformations for the Baltimore- Washington region. This multiple agency effort includes collaboration with the Bureau of the Census, the University of California at Santa Barbara, the NASA Goddard Space Flight Center, and numerous other federal, state, local, and private institutions. Previous research by the USGS, as part of the U.S. Global Change Research Program, documented the potential of urban mapping research activities to study urban transition processes from an historical and multi-scale perspective appropriate for modeling and predicting regional patterns of urbanization into the future (Kirkland et al., 1994). That effort involved mapping the growth of urban development for the San Francisco Bay area using archival topographic maps and Landsat satellite images to delineate changes in the urban extent over time (Bell et al., 1995). The methodologies were expanded for the Baltimore- Washington effort to promote a variety of environmental, social, and economic models related to urban-rural dynamics.



The Collaboratory project team created a multi-phased research plan, Table 1, which entails the creation of a multi-thematic, multi-temporal, multi-scale and resolution, spatial database structure for the greater Baltimore-Washington region, Figure 1.




This multi-year collaboration continues to support activities assembling an integrated and flexible temporally based, urban land characteristics database encompassing the period from 1792 to 1992. Phase I focused on testing the previous methodologies for an area encompassing the greater Baltimore metropolitan area. Database design and construction, metadata documentation, and basic visualization methods have been tested and implemented using the Phase 1 database (Acevedo et al., 1996; Masuoka et al, 1995; 1996). Phase II efforts have expanded the database development for the entire 2-degree by 2-degree region. Phase III and IV will focus on experimenting with selected mapping themes, analyzing spatial patterns and rates, and linking with various local, regional, and global environmental models. Included in the Phase I and II database development are temporal mapping layers for primary transportation, hydrography, and population density. Derivation of these data layers comes from the archives of historic maps and records prior to 1970's and digital data in the post 1970's era using Landsat imagery, Digital Line Graphs, Digital Elevation Models, and DIME and TIGER files. The resulting database of temporal urban demographic changes, which forms the framework of the Baltimore-Washington testbed, provides an ideal source of information to calibrate and verify models for urban geographers, environmental scientists, and global change scientists. Figure 2 displays the results of the Collaboratory analysis of urbanization dynamics for a two hundred year period.


Figure 2: Two Hundred Years of Urbanization in the Chesapeake Bay Region



Contributing agencies and the expansion of activities related to the Baltimore-Washington regional spatial database are lending support to the testbed concept. This testbed provides a distributed, Internet accessible resource for environmental scientists as well as interested local and regional planners. Activities associated with the Baltimore-Washington Collaboratory include data visualization research, NSDI metadata compliance and testing, user community outreach, and applied science modeling. A multi-disciplinary team has expanded on methodology, definitions, and collection criteria used to define the various data layers, ensuring consistency in data definitions and data collection techniques among the different collaborators.

DESIGN AND IMPLEMENTATION OF THE BALTIMORE-WASHINGTON REGIONAL COLLABORATORY

Successful approaches to system design of large spatial (GIS) databases have been adapted from the rich experiences of non-spatial systems engineering protocols (Calkins, 1982). From this setting a GIS database designer can construct the bounding parameters of systems, data, people, and financial resources into a conceptual template for the database to exist and perform its primary function. For the Baltimore-Washington Collaboratory, the design of the spatial database requires attention to new demands outside the traditional GIS construction domain. This system design is based on the realities of the collaborating data providers and users including some of the following perspectives.

The Collaboratory is following the general constructs of both the National Spatial Data Infrastructure (FGDC, 1995) and the NASA Mission to Planet Earth (MTPE) plans for handling Earth observations from space (National Research Council, 1995). Environmental modelers, will be able to use Collaboratory assets for both model input and as calibration/validation tool for their models, as a result of thorough metadata documentation for these data resources. Other users will likely view the Collaboratory as a source of input for regional planning purposes to analyze and predict rates of land use change and the sensitivity of causal factors related to the land use transitional processes. Members of the modeling community are expected to capitalize on these resources as they develop integrated regional models to couple environmental, human, and physical models (Blood, 1994). These modelers will be instrumental in refining both the content and structure of the Collaboratory's assets related to linking regional and global models. It therefore becomes incumbent on the Collaboratory designers and modeling community to creatively deal with issues of calibration, validation, uncertainty and error propagation, simplification or aggregation, resolution and scale as they impact the performance of integrated regional models or environmental models in general. The Collaboratory design must take into account these issues and therefore the design must in part be continually assessed on a case by case basis. Attention to the ramifications of any design constraints on the use of the spatial database for general modeling applications has led to a conservative approach to the creation and documentation of the spatial database.

The Baltimore-Washington Collaboratory designers assume data assets to be either digital vector or raster with associated attribute files and metadata. Data sets initially represented in the Collaboratory are listed in Figure 3. Many vector datasets will be converted to grid formats for input in cellular autonoma, finite element or finite difference modeling structures (Coucleilis, 1985; Clarke et al, 1996). Vector data sets will be used for referencing of geographic phenomena, via hydrology or transportation alignments, or as vector overlays for improved comprehension of associated datasets. Error propagation attendant to vector to raster conversion remains unavoidable.


Figure 3: Baltimore-Washington Regional Collaboratory Baseline Data Resources

Proposed Thematic/Spatial Coverage



Physical location of the Collaboratory's spatial database assets is distributed among the cooperating data providers and accessible via the Internet or in bulk media formats. Under the guidance of NASA's Earth Observing System Data and Information Systems (EOSDIS) general protocols, a few nodes may have additional responsibilities to serve as part of a regional data center (RDC). A key design assumption for the Collaboratory is that data providers (e.g., NASA, USGS, NOAA) remain stewards of their data whenever possible, to maintain full metadata documentation, and provide updates and upgrades to data as appropriate. The Collaboratory will ensure that data resources included in the data catalog have complied with cooperative protocols for Federal Geographic Data Committee (FGDC) metadata.

Both federal and Maryland State agencies have been directed to comply with federal metadata standards (FGDC, 1994). Data available through the Collaboratory varies in format and quality, however, the attention to the details of metadata documentation will provide environmental modelers with the information required to determine goodness-of-fit for their modeling use. While the federal metadata standards have been viewed by many as unfunded mandates, compliance offers the modeling community a rich resource of digital data reducing the uncertainty of their modeling parameters. Adherence to metadata documentation is not a trivial exercise and has required significant use of project personnel resources. Numerous technical problems have been discovered in the implementation of the FGDC metadata standards within the GIS framework. Testing the performance of search engines at varying levels of metadata documentation is required to determine the appropriateness of the current FGDC structure. Results from the Baltimore-Washington Collaboratory have demonstrated the usefulness of an hierarchical approach to metadata documentation under a hybrid FGDC schema being testing (Foresman, et al, 1996). The hybrid approach is based on the requirement of including large quantities of local and regional digital data resources from agencies not bound by federal or state standards. The challenge resides in the ability to harness data resources available through the Collaboratory at fine resolution scales (1 meter to 10 meters) while still attending to the philosophy for goodness-of-fit labeling requirements, Figure 3.

The RDC design considerations add requirements for various preprocessing steps of remotely sensed data. This will make the data suitable for some local or regional users and environmental modelers. For example, AVHRR or Landsat data requires some data format handling before it can be used on desktop, personal computer GIS software packages available to county planners and decision makers. As an RDC, the Baltimore-Washington Collaboratory, using personnel from UMBC and NASA Goddard Space Flight Center will be working with various environmental modelers. An environmental application example incorporates the testing of the HSPF hydrologic model for performance along an urban-rural gradient using Collaboratory input parameters. A study of how HSPF performs along this gradient at cascading spatial scales or grid resolutions is planned in cooperation with personnel of the USGS, Yale School of Forestry, and the Institute of Ecosystem Studies. The Collaboratory can serve in an iterative fashion to both supply data for modeling and to share the results back to the community for assessment and planning purposes. Professor Keith Clarke (1996) is planning to test and calibrate an urban growth cellular autonomon model using Collaboratory data. His modeling results should be available over the Internet in the near future complete with operating code and data. This approach will provide local land use managers with essentially no-cost tools to examine population growth for their regions 50 years into the future.

The Baltimore-Washington Collaboratory will also serve the remote sensing community to verify, calibrate, and validate remotely sensed data. Careful geographic registration of the regional infrastructure, land use, demographics, topography, and other physical data sets, as part of the Collaboratory shared digital resources, can provide crucial ground truth for calibration. This becomes increasingly important as a host of new sensors being developed for the EOS program begin to produce data. These activities will assist the user communities of local environmental and land use managers, and planners, and commercial entities to determine the applicability of EOS information for their local/regional applications.

CONCLUSION

The design of a regional, digital spatial data resource has been established with a general topology- relational GIS database structure to support the ready import of data for a variety of regional environmental models. A regional spatial data testbed is considered critical for the environmental community to calibrate, verify, and validate the various models. The use of object or feature base representation for spatial, temporal, and attribute modeling continues to show much progress, as reported by Raper and Livingston (1995) and others (Guptill, 1988; Shi and Zang, 1995). A regional digital database however, must attend to the needs of the many and therefore a conservative GIS structure has been initially selected for the Baltimore-Washington Collaboratory. By aligning the Collaboratory protocols with national standards and trends, modelers using the digital data resources can benefit from working in the context of the national spatial data infrastructure where efforts to correct and improve the national protocols will result in more meaningful approaches for long-term use of their models at regional and global scales.

Integrated environmental modeling assessments and integrated regional models require better understanding of the semantics and parameter formats of different modeling schools. These models, using GIS data structures and resources, may require significant modification to extend into the domains of human ecology, urban environments, landscape ecology, sustainability, and ecological economics to meet the demands for improved decision making and management applications. Through the application of quality documented data resources, available from RDCs such as the Baltimore-Washington Collaboratory, it is envisioned that development of integrated environmental models at regional to global scales can be better accomplished in the future.

ACKNOWLEDGMENTS

This research involves the efforts of many in the U.S. Geological Survey, the University of Maryland Baltimore County, the Bureau of the Census, and the National Aeronautics and Space Administration. This research is funded in part by NASA Research Grant NAGW-1743. For further information, please investigate our homepage at http://www.umbc.edu/bwrdc.


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Dr. Timothy W. Foresman
Director, Laboratory for Spatial Analysis
Department of Geography
University of Maryland Baltimore County
5401 Wilkens Avenue
Baltimore, MD 21228
Telephone: 410-455-3149
Fax: 410-455-1056
E-mail: foresman@umbc.edu