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Using geographic information systems to assess conflicts between agriculture and development
Landscape
and I’rban Planning,
333
16 ( 1988 ) 333-343
Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
USING GEOGRAPHIC INFORMATION SYSTEMS TO ASSESS CONFLICTS BETWEEN AGRICULTURE AND DEVELOPMENT MARK S. LINDHULT, Department
qfLandscape
Architecture
JULIUS and Regional
FABOS, PAM BROWN Planning.
and NANCY
University OfMassachusetts,
Amherst,
PRICE MA 01003 (U.S.A.)
ABSTRACT
Lindhult, M.S., Fabos, J., Brown, P. and Prince, N., 1988. Using geographic information systems to assess conflicts between agriculture and development. Landscape Urban Plann., 16: 333-343.
The conflict between agriculture and urban development is intense in urbanizing areas of the United States and is a problem best resolved at the local level. To effectively develop and applv techniques for preserving farmland, areas of
INTRODUCTION The conversion of agricultural land to other uses is a problem of national concern in the United States. Farmland is steadily being whittled away. Between 1968 and 1975 over 24.6 million acres ( 10 million ha) of farmland were converted into urban and other uses in the United States, never to be returned to farmland (Keene, 198 1 ). Currently, the United States is losing 20 000 acres ( 8 100 ha) of agricultural land each week, or 3 million acres ( 1 215 00 ha) year-’ (U.S. Soil Conservation Service). Although conversion of agri0169-2046/88/$03.50
0 1988 Elsevier Science Publishers B.V.
conflict must be identified. This article describes the application of a geographic information system (GIS) for determining the location and level of conflict between agriculture and otherforms ofhuman intervention. The procedures used for assessing conflicts are described through a case study in the city of Westfield, Massachusetts and thejndings show that GIS can be an effective tool for local decision makers, allowing alternative strategies to be developed and evaluatedfor agriculturalprotection
cultural land is clearly a national problem, it is one that can be best dealt with at the regional, state and local levels (Jeffords, 1984). In Massachusetts, where there were 30 000 farmers working over 2 million acres of land in the 1940’s, there are now only about 5900 farmers working less than 680 000 acres of land (USDA, 1983). The importance of agriculture is not, by any means, limited to its economic importance as an industry. There is much local concern about protecting and preserving the cultural heritage of western Massachusetts. Farmland provides a vital source of open space, in terms of both its visual character and eco-
334
logical importance. In recognizing the many values possessed by agriculture, the Massachusetts legislature has spent over $30 million in the past 3 years for the purchase of development rights on agricultural land. Currently there is a proposal for an open space bond which proposes to add another $27 million for this purpose. In addition, legislation is proposed to permit land banks at the local level, a fund generated through a 2% surcharge on all real estate transactions, of which 50% will typically go towards the purchase of open space and agricultural land. There are numerous strategies that can be used for protecting farmland, from restrictive zoning to land banks. However, all methods require knowledge of the existing resources and the degree of conflict that exists between farmland and urban development. The computer can be utilized by local planners to identify and measure the level of conflict. Such information is essential for the development and evaluation of strategies for the protection of farmland. To be successful, a plan for farmland protection must be one aspect of a larger ongoing planning process. Agricultural land retention viewed in this context is a complex issue requiring consideration of several independent and related factors. The Metropolitan Landscape Planning Model ( METLAND ) provides a logical, clear, step-by-step process for dealing with complex issues of this type. The METLAND Planning Project is an ongoing research effort that represents a comprehensive approach to landscape and resource assessment. This planning approach has been developed over the past 17 years by a multidisciplinary team of landscape architects, planners, economists and social and natural scientists at the University of Massachusetts. One of the primary objectives of this research has been to aid decision makers in overcoming the negative effects, costs and uncertainties generated by incremental development by providing pertinent information on specific land
areas where changes occur (Gross et al., 1984 ), The METLAND model has three components: ( 1) assessment of landscape resources: (2) generation of land-use plans using this information; ( 3 ) evaluation of these plans based on specific criteria. Each of these components could be completed by hand using manual overlay techniques, but, because of the vast amounts of data, this would be an extremely long and tedious process. Such a manual process can be used to assess only a limited number of factors and generate only two or three alternatives. An evaluation of these alternatives is most often limited to intuitive judgments. The computer has evolved as an effective tool for organizing spatial and tabular data into an understandable and usable form for decision makers. It can assess a great number of spatial factors. The user can generate and test an infinite number of alternatives, each taking hours instead of weeks. Especially important are evaluation procedures which are available to determine or estimate the consequences of each action (Gross et al., 1984). This tool has been recognized and developed into the field of Geographic Information Systems. WORKSTATION-BASED GEOGRAPHIC INFORMATION SYSTEMS A geographic information system (GIS) is a collection of computer hardware and software designed to accept and store large volumes of spatial and tabular data derived from a variety of sources. The user of a GIS can retrieve, manipulate, analyze and display the data according to predefined specifications (Hendrix and Smith, I985 ). There are 3 basic components of any GIS. ( 1) Data input is required to convert conventional paper or mylar maps into a digital or computer-readable form through digitizing or scanning. Tabular information related to the digital maps is entered into a database. The tabular data are linked to the spatial
335
data by a label that identifies what exists in a certain region of a map (Fig. 1) . (2) Analysis and manipulation. These are procedures performed by the GIS to look for particular attributes or combinations of attributes of a particular geographic region. The computer electronically overlays maps and determines where particular conditions coincide. (3 ) Extracting and displaying data. The user can search for, find and display desired information in a variety of ways. A display can be spatial region-filled maps which may be output to color plotters or ink-jet printers. Information related to these maps can be output as tabular data and statistics. The major advantage of GIS when compared with traditional planning procedures is the remarkable speed with which the computer is able to search through large volumes of data and generate output that matches user-specified criteria. This speed allows a decision
Farm
maker to consider several alternatives based on different criteria for a given problem. Over the last decade, GIS technology has proven to be a useful tool for federal and state agencies and large corporations in making landscape and resource decisions. The thrust of the METLAND approach to geographic information systems is to move this powerful planning tool, once wholly dependent upon expensive mainframes and minithe affordable computers, down to microcomputer workstation environment. The workstation-based GIS offers the opportunity for truly participatory planning by allowing local planners and citizens groups to simulate the effects of zoning, ownership and land-use changes (Lindhult and Waltuch, 1985 ). An objective of METLAND has been to develop a workstation-based GIS for local planners that is powerful, affordable and easy to use. The system’s power is derived from the new generation of workstations (METLAND
Parcels
Soils Zoning Flood Plain Sewer
Parcel
Farmer
12 25 148 69 51
Years to go
Other Family
= of Offers
lo+ 5+ 2
Y N Y
3 0 5
15
N
1
_-
N 5
Fig. 1. Each region on a map is given a label which links the spatial data with the tabular data base.
336
is based on the SUN family of workstations, although it is adaptable to other UNIX-based machines) that have the power of recent mainframes. Because the system is intended for local planning officials, cost was a major determinant in the overall design. The target was a system that costs less than $25 000 for all hardware and software. Ease of use is especially important with agencies that can not afford specialized computer personnel. This meant the creation of a simplified method of entering data and queries into the computer so that the planner does not have to worry about “command structures” and can concentrate on the problem. In addition to its low cost, another advantage of the METLAND GIS is that it is a poly-
New
gon-based system. Unlike most GIS which convert spatial information relating to soils, land use and other data into grid cells, all data is manipulated in polygon form through a network-clipping algorithm (Waltuch and Hoffman, 1986). This is important when dealing with applications such as the case study which depends heavily on the accuracy of property boundaries and their relationship to other landbased information.
CASE STUDY A case study involving the city of Westfield, MA highlights the issues relevant to the application of workstation-based GIS technology to farmland preservation as well as other land-use
England
States
nn
0 5
0’
NEW
HAMPSHIRE
MASSACHUSETTS
10
15
miles
25 kilometers
337
!02
90
Fig. 2. The location of Westfield, Massachusetts
and the distribution
decisions. The city of Westfield belongs to a group of west-central Massachusetts towns that lie in the valley surrounding the Connecticut River (Fig. 2). The city covers 47.5 square miles; its population is approximately 36 500 and growing rapidly, 13.8% between 1970 and 1980 at a time when the county lost 3.8% of its population. The purpose of the project was to assist the city of Westfield’s Department of Community Development in determining the extent and location of conflict between urban development (industrial, commercial and residential) and the city’s farmland (a “city” in Massachusetts can encompass non-urban land since all land is part of an incorporated unit ) . The project was unusual in that it involved cooperation between the city of Westfield, the USDA Soil Conservation Service, the Massachusetts Cooperative Extension Service and the MET-
of farm parcels within the city.
LAND research team. The project also fulfilled the ideal of being a participatory project which centered around a volunteer farmland advisory committee which assisted in the development of questionnaires and data collection. The objectives The four major objectives of the project were to provide the City with methods to: ( 1) determine what areas of Westfield contain important farmland under active agricultural use; (2) determine which areas of the city are most suited for development; (3 ) assess the degree of conflict between agriculture and development in the city; (4 ) identify farm parcels that meet the criteria for the Massachusetts Agricultural Preservation Restriction (APR) Program, a state-
338
funded program that allows selected farmers to sell their development rights to the state at fair market value. Data sources
The first step in the process was the formation of a farmland advisory committee composed of farmers, developers, city board members and other citizens concerned with the future of Westfield’s farmland, all of whom participated in setting the direction of the committee. An extension service specialist was the group’s coordinator, 2 METLAND researchers served as liaisons to keep the cominformation informed about mittee METLAND was gathering and an SCS planner provided important input to the project. All listened to the farmers’ ideas about farmland in the city. The farmland advisory committee developed a questionnaire and conducted a survey of Westfield farmers in order to gather detailed information about individual farm parcels. Farmland is scattered throughout the city, with approximately 152 farm parcels in Westfield totaling 5594 acres, 18.5% of the total land area. Surveys were returned by 18 dairy, 6 beef, 7 hay, 6 vegetable, 3 fruit, 2 livestock, 3 forestry, 1 orchard and 2 other farmers, reporting on 4 012 acres of land. A majority of the nonresponding “farmers” were absentee landowners. Maps of Westfield were digitized and entered into the computer. This information included data on soils, land use/land cover, flood plain, surface zoning, 1% probability water, roads and railroads, slope, existing sewer and water lines and farmland parcels. ASSESSMENT
PROCEDURES
To determine the actual conflict that existed between agriculture and urban development, it was necessary to assess the land’s inherent productivity, development pressures that were
impacting the City of Westfield and development suitability issues which could aid the city to find alternative non-agricultural land for development. To accomplish this, 5 assessment procedures had to be developed, one for each of the following categories of land potential. An assessment procedure can be defined as the quantification of resource values for certain use potentials. ( 1 ) Agricultural productivity potential. (2 ) Municipal/administrative forces - development pressure according to zoning, public utilities and other municipal/administrative forces. (3) Commitment to agriculture - development pressure according to farmers’ commitment and external forces. (4) Physical development suitability. ( 5 ) Flood plain hazard areas. Agricultural productivity potential
A 3-step procedure was used to determine the agricultural productivity rating for any given area of land. First, the 270 soil types and classes were aggregated into 5 soil suitability groups, according to a modified version of the Land Evaluation System (LESA) developed by the Soil Conservation Service of the U.S. Department of Agriculture. The modifications were necessary since the LESA system is biased towards “in-ground” crops, such as vegetables, and soil suitability was determined according to its ability to support these crops. However, Westfield’s farmland is characterized by only 9% vegetable crops and 18% silage corn. Most farmland in Westfield (73%) is used for dairy, beef, orchards and other forms of agriculture. Second, the degree to which current land use detracts from soil suitability was considered. The 104 land-use types (MacConnell, 1975) were aggregated into 5 groups based on relative impact of land use on the agricultural productivity of the soil (Fabos and Caswell, 1977 ). For example, a parcel of land with excellent agricultural soils that was covered with
339
housing is very unlikely to be put back into agricultural production. The degree of detraction is expressed as the cost of restoring the land from its current use to productive agricultural use. The computerized land-use map was used to group land uses and to store an aggregated map of the land according to these detractor ratings. The final step involved an overlay of the aggregated soil suitability and detractor maps, and determination of high to low agricultural productivity ratings. The final agricultural productivity assessment map was produced on the computer, with ratings of AA, A, B, C or D assigned according to the combined values of soil suitability and land use (Prince, 1985 ). Municipal/administrative
forces
The first of 2 assessments of development pressure was developed specifically for this study. It involved the use of spatial and municipal/administrative data. This procedure involved the rating of land parcels for 5 factors that contribute to the conversion of farms to non-farm use: ( 1) proximity to public utilities - sewer and water lines; (2) adjacent land use - percentage of land in agricultural use with a 0.25 mile radius of the parcel; ( 3 ) zoning of the farm parcel - agricultural or open space, industrial/commercial or residential; (4) the tax classification of the farm parcel whether or not it was assessed with a differential property tax based on the parcel’s agricultural use; ( 5 ) proximity of the farm to improved roads. Each factor was rated A, B or C, in decreasing order of the pressure on a farmer to sell land to a developer. Commitment
to agriculture
The second assessment of development pressure evaluated the farmer’s current and fu-
ture commitment to agriculture based on three questions from the farmer survey: ( 1) the number of years the farmer intended to continue farming; (2) whether or not there was a family member or other interested in continuing the farm operation; (3) the number of offers the farmer has had for purchase of his land in the past 5 years. Physical development suitability
The assessment of physical suitability for development was based on earlier METLAND procedures (Fabos and Caswell, 1977) to determine the cost of development. This procedure assessed 5 soil characteristics: depth to bedrock, depth to water table, drainage, slope and quality of topsoil. Each of the soil characteristics poses its own limitation on development and there was an associated cost involved to overcome that limitation. For each soil type, the costs for overcoming each limitation are added and rank ordered in tabular form, then displayed spatially on the screen or printed out. This list of development costs was attached to the soils data base and was used to aggregate the soils spatially. A very low rating for development suitability does not preclude development from taking place. It indicates that the cost for developing the parcel will be quite high and assumes a developer will look for a site that has fewer restrictions, thus reducing costs. Flood hazard
Many areas, especially good farmland located near rivers, are prone to flooding. The flood hazard assessment served to identify lands within the 1% probability flood plain. It is important to restrict or limit the amount of development within the flood plain to minimize damage and prevent the loss of life associated with major floods.
340
APPLICATION
OF ASSESSMENTS
The 5 assessment procedures were developed for a series of specific applications, of which 2 are described. The first determines the degree of conflict between agriculture and development and where that conflict is occurring. This procedure uses the flood plain and development suitability assessments along with the farm parcels map to assess the conflict. The second application discusses how this information can be applied to a specific planning issue once the conflicts are determined. This application uses all 5 assessments. The application of these assessments links the community planner’s values, knowledge and judgement with the tremendous data storage, manipulation and display capabilities of the workstation-based GIS (Lindhult and Waltuch, 1985). Identifying conflicts between agriculture and development To make any attempt at preserving farmland and finding appropriate locations for development that do not conflict with agricultural activities, the planner must first identify where potential conflicts exist and the extent of those conflicts. Without a clear understanding of this information, it is difficult to make appropriate land-use decisions. In the case of Westfield, the first step was to identify what parcels enjoyed limited protection from the flood plain. Westfield has two large contiguous areas of flood plain adjacent to the Westfield River (Fig. 3 ). An overlay map was generated of the flood plain and farm parcels which showed that 13 individual farm parcels have at least 50% of their land area within the flood plain. Throughout the rest of the city the flood hazard line passes through all or part of 29 additional farm parcels. This means that 42 of the 152 farm parcels in Westfield have limited protection due to restrictions on development within the flood plain. The total
acreage comes to 540 acres or 10% of the total farmland. This figure can be somewhat misleading in that a developer can still purchase a parcel and only develop on upland areas away from the flood plain, thus removing the parcel from agricultural use. The remaining 90% of Westfield’s farmland is still available for potential development. The next step was to overlay farm parcels with the physical development suitability map. Areas of potential conflict between agriculture and development became quite obvious. The prime or least-cost class ( 1 out of 4) for development constituted an area of 8860 acres in Westfield, of which 1926 acres lie on farmland in parcels ranging from 1 1 to 300 acres. The 1926 acres are 22% of the prime developable area and 35% of the farmland. The three classes ( 1, 2 and 3 that do not pose severe development restrictions cover a total of 1 1 783 acres of which 3667 acres (31%) are in active agriculture. This leaves 8 116 acres available for development. These results indicate that Westfield has abundant land available for development without using the current farm parcels (Fig. 4). Although this is a lot of land, one must not give in to the assumption that no problem exists. Agricultural land is an attractive commodity to developers since it is typically in a large block, thus reducing the need for assembling several different parcels. The GIS allowed the planner to identify where the best developable land is in Westfield and how it relates to the location of active farm parcels. This allowed various strategies to be formulated about how development could be directed to prime developable areas located away from agricultural land. Decisions such as the placement of proposed sewer lines greatly impact the future of farmland. Fifty-five percent (55%) of Westfield is zoned for agriculture while only 18.4% is in active agricultural use. What is needed is a rezoning effort which considers this large block of land relative to its development potential and which designates appropriate uses.
341
Kilometks
Fig. 3. The location of the flood plain in relationship to the farm parcels.
The procedure for determining the degree of conflict between agriculture and development appears extremely simple and straightforward. However, one must consider that none of the assessments is written in stone. Interest groups and individuals may desire to modify these assessments, thus changing the results. This is where the workstation-based GIS excels. Instead of working for days to prepare a new map showing a group’s interpretation, the computer can quickly generate a map showing the spatial distribution of the results. This makes it possible to direct the discussion towards the actual differences that result from new interpretations. Specific planning applications
The application of the assessment procedures is relevant not only to the identification
of conflicts, but to other spatial planning problems as well. The Massachusetts Agricultural Preservation Restriction Program (APR) illustrates this process. APR is a highly competitive program that gives preference to protecting those farms which are facing imminent development pressure. To determine which farms are potential candidates for this program, the following APR criteria were entered into the computer: ( 1) to look for the farms with the highest agricultural potential; (2 ) to see which farms were under the highest in terms of proximity to pressure infrastucture; (3 ) to estimate the likelihood of a farmer or his heirs continuing the agricultural use of the land; (4) to see which parcels were highly suitable
342
Excellent Good Acceptable Poor Downtown Westfield
L/q Fig. 4. Development
1
2 Kilometers
suitability ranking for soils in Westfield.
for development and therefore likely to be targets of developers; (5) to see what areas are already indirectly protected because of flood plain development restrictions. By applying the 5 assessment procedures, a map was generated illustrating which farms most closely fit the APR criteria and thus had the greatest potential for receiving state support. The workstation-based GIS can only identify parcels that meet the user-specified criteria; it is not designed to take into account political judgments that are intuitive to a planner. The computer’s main use is to substantially narrow down the likely parcels, in this case 152 to 3, so that a community can focus educational efforts about farmland protection towards those farmers who face the greatest pressure. This type of procedure relieves the
planner of the tedious and time-consuming task of evaluating all land parcels against a program’s criteria. CONCLUSION Workstation-based GIS is expected to be used in the near future by local planners to generate land-use scenarios that will identify where development should occur in order to protect valuable agricultural resources. Planners will be able to utilize this tool to quickly avail themselves of current information. In place of the limited application of information used in similar types of situations, the computer permitted us to use 5 relevant data sets and combine them to produce composite assessments. Using the workstation-based GIS, the plan-
343
ner can develop more sophisticated techniques of assessing information rather than relying on simplistic procedures necessitated by manual labor. Information can be combined in a multitude of ways and in a short period of time, allowing the planner and the public to evaluate a larger number of potential alternatives to planning problems. Planning is a learning process and decision making involves many players. The workstation-based GIS can articulate the decision making by mapping out alternative plans for each interest group or individual. The benefit is the ability to add meaningful public participation; where an idea, opinion or answer to a question can be expressed spatially, the pros and cons of each alternative can be evaluated against environmental and cultural criteria. It was found that one of the major benefits of the GIS to the city was as a cartographic tool. As in most communities, the 8 major maps used by the Department of Community Development were at 6 different scales, making it impossible to overlay maps to extract information. The establishment of a computerized geographic data base resolved this through digitizing the maps, putting them into digital form, which allowed the maps to be plotted at a common scale for simple manual overlays. The protection of farmland must be integrated into a comprehensive planning process that evaluates all land-use decisions in a community. The workstation-based GIS provides planners with a tool to run a series of land-use scenarios and evaluate their spatial consequences. This can only bode well for the protection of our valuable farmland resources.
REFERENCES Fabos, J. and Caswell, S.J., 1977. Composite Landscape Assessment. Research Bulletin No. 637, Massachusetts Agricultural Experiment Station, University of Massachusetts at Amherst. Gross, M., Bucko, D., Fabos, J. and Foster, J., 1984. Landscape Planning and Evaluation: A Combined Goal-oriented and Benefit Loss Approach. Research Bulletin No. 692, Massachusetts Agricultural Experiment Station, University of Massachusetts at Amherst. Hendrix, W. and Smith, G., 1985. The application of geographic information system technology for resource management and landscape planning. Proceedings from Landscape/Landuse Planning Session, American Society of Landscape Architects Annual Meeting, pp. 38-46. Jeffords, J.M., 1984. The loss of U.S. cropland: whose issue is it? In: F.R. Steiner and J.G. Theilacker (Editors), Protecting Farmlands. AVI Publishing Co., Westport, CT, pp. 3-14. Keene, J., 198 1. Executive Summary, Loss of Valuable Agricultural Land, The Problem and Its Causes. In: R.E. Caughlin and J.C. Keene (Editors), National Agricultural Lands Study; The Protection of Farmland: A Reference Guidebook for State and Local Governments. U.S. Government Printing Office, Washington, DC. Lindhult, M. and Waltuch, M., 1985. Workstations on the cutting edge of landscape planning. Proceedings from Landscape/Landuse Planning Session, American Society of Landscape Architects Annual Meeting, pp. 47-54. MacConnell, W.P., 1975. Remote Sensing 20 Years of Change in Massachusetts I95 l/2-1 97 l/2. Research Bulletin No. 630, Massachusetts Agricultural Experiment Station, University of Massachusetts at Amherst. Prince, N., 1985. Farmland preservation in the city of Westfield, MA: a computer-aided planning approach. Unpublished Masters Project. U.S. Department of Agriculture, 1983. National Agricultural Land Evaluation and Site Assessment (LESA) Handbook. USDA Soil Conservation Service, Washington, DC. Waltuch, M. and Hoffman, J., 1986. MAPLE: A workstation based GIS for landscapes and the environment. Proceedings from Landscape/Landuse Planning Session, American Society of Landscape Architects Annual Meeting, pp. 72-76.
and I’rban Planning,
333
16 ( 1988 ) 333-343
Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
USING GEOGRAPHIC INFORMATION SYSTEMS TO ASSESS CONFLICTS BETWEEN AGRICULTURE AND DEVELOPMENT MARK S. LINDHULT, Department
qfLandscape
Architecture
JULIUS and Regional
FABOS, PAM BROWN Planning.
and NANCY
University OfMassachusetts,
Amherst,
PRICE MA 01003 (U.S.A.)
ABSTRACT
Lindhult, M.S., Fabos, J., Brown, P. and Prince, N., 1988. Using geographic information systems to assess conflicts between agriculture and development. Landscape Urban Plann., 16: 333-343.
The conflict between agriculture and urban development is intense in urbanizing areas of the United States and is a problem best resolved at the local level. To effectively develop and applv techniques for preserving farmland, areas of
INTRODUCTION The conversion of agricultural land to other uses is a problem of national concern in the United States. Farmland is steadily being whittled away. Between 1968 and 1975 over 24.6 million acres ( 10 million ha) of farmland were converted into urban and other uses in the United States, never to be returned to farmland (Keene, 198 1 ). Currently, the United States is losing 20 000 acres ( 8 100 ha) of agricultural land each week, or 3 million acres ( 1 215 00 ha) year-’ (U.S. Soil Conservation Service). Although conversion of agri0169-2046/88/$03.50
0 1988 Elsevier Science Publishers B.V.
conflict must be identified. This article describes the application of a geographic information system (GIS) for determining the location and level of conflict between agriculture and otherforms ofhuman intervention. The procedures used for assessing conflicts are described through a case study in the city of Westfield, Massachusetts and thejndings show that GIS can be an effective tool for local decision makers, allowing alternative strategies to be developed and evaluatedfor agriculturalprotection
cultural land is clearly a national problem, it is one that can be best dealt with at the regional, state and local levels (Jeffords, 1984). In Massachusetts, where there were 30 000 farmers working over 2 million acres of land in the 1940’s, there are now only about 5900 farmers working less than 680 000 acres of land (USDA, 1983). The importance of agriculture is not, by any means, limited to its economic importance as an industry. There is much local concern about protecting and preserving the cultural heritage of western Massachusetts. Farmland provides a vital source of open space, in terms of both its visual character and eco-
334
logical importance. In recognizing the many values possessed by agriculture, the Massachusetts legislature has spent over $30 million in the past 3 years for the purchase of development rights on agricultural land. Currently there is a proposal for an open space bond which proposes to add another $27 million for this purpose. In addition, legislation is proposed to permit land banks at the local level, a fund generated through a 2% surcharge on all real estate transactions, of which 50% will typically go towards the purchase of open space and agricultural land. There are numerous strategies that can be used for protecting farmland, from restrictive zoning to land banks. However, all methods require knowledge of the existing resources and the degree of conflict that exists between farmland and urban development. The computer can be utilized by local planners to identify and measure the level of conflict. Such information is essential for the development and evaluation of strategies for the protection of farmland. To be successful, a plan for farmland protection must be one aspect of a larger ongoing planning process. Agricultural land retention viewed in this context is a complex issue requiring consideration of several independent and related factors. The Metropolitan Landscape Planning Model ( METLAND ) provides a logical, clear, step-by-step process for dealing with complex issues of this type. The METLAND Planning Project is an ongoing research effort that represents a comprehensive approach to landscape and resource assessment. This planning approach has been developed over the past 17 years by a multidisciplinary team of landscape architects, planners, economists and social and natural scientists at the University of Massachusetts. One of the primary objectives of this research has been to aid decision makers in overcoming the negative effects, costs and uncertainties generated by incremental development by providing pertinent information on specific land
areas where changes occur (Gross et al., 1984 ), The METLAND model has three components: ( 1) assessment of landscape resources: (2) generation of land-use plans using this information; ( 3 ) evaluation of these plans based on specific criteria. Each of these components could be completed by hand using manual overlay techniques, but, because of the vast amounts of data, this would be an extremely long and tedious process. Such a manual process can be used to assess only a limited number of factors and generate only two or three alternatives. An evaluation of these alternatives is most often limited to intuitive judgments. The computer has evolved as an effective tool for organizing spatial and tabular data into an understandable and usable form for decision makers. It can assess a great number of spatial factors. The user can generate and test an infinite number of alternatives, each taking hours instead of weeks. Especially important are evaluation procedures which are available to determine or estimate the consequences of each action (Gross et al., 1984). This tool has been recognized and developed into the field of Geographic Information Systems. WORKSTATION-BASED GEOGRAPHIC INFORMATION SYSTEMS A geographic information system (GIS) is a collection of computer hardware and software designed to accept and store large volumes of spatial and tabular data derived from a variety of sources. The user of a GIS can retrieve, manipulate, analyze and display the data according to predefined specifications (Hendrix and Smith, I985 ). There are 3 basic components of any GIS. ( 1) Data input is required to convert conventional paper or mylar maps into a digital or computer-readable form through digitizing or scanning. Tabular information related to the digital maps is entered into a database. The tabular data are linked to the spatial
335
data by a label that identifies what exists in a certain region of a map (Fig. 1) . (2) Analysis and manipulation. These are procedures performed by the GIS to look for particular attributes or combinations of attributes of a particular geographic region. The computer electronically overlays maps and determines where particular conditions coincide. (3 ) Extracting and displaying data. The user can search for, find and display desired information in a variety of ways. A display can be spatial region-filled maps which may be output to color plotters or ink-jet printers. Information related to these maps can be output as tabular data and statistics. The major advantage of GIS when compared with traditional planning procedures is the remarkable speed with which the computer is able to search through large volumes of data and generate output that matches user-specified criteria. This speed allows a decision
Farm
maker to consider several alternatives based on different criteria for a given problem. Over the last decade, GIS technology has proven to be a useful tool for federal and state agencies and large corporations in making landscape and resource decisions. The thrust of the METLAND approach to geographic information systems is to move this powerful planning tool, once wholly dependent upon expensive mainframes and minithe affordable computers, down to microcomputer workstation environment. The workstation-based GIS offers the opportunity for truly participatory planning by allowing local planners and citizens groups to simulate the effects of zoning, ownership and land-use changes (Lindhult and Waltuch, 1985 ). An objective of METLAND has been to develop a workstation-based GIS for local planners that is powerful, affordable and easy to use. The system’s power is derived from the new generation of workstations (METLAND
Parcels
Soils Zoning Flood Plain Sewer
Parcel
Farmer
12 25 148 69 51
Years to go
Other Family
= of Offers
lo+ 5+ 2
Y N Y
3 0 5
15
N
1
_-
N 5
Fig. 1. Each region on a map is given a label which links the spatial data with the tabular data base.
336
is based on the SUN family of workstations, although it is adaptable to other UNIX-based machines) that have the power of recent mainframes. Because the system is intended for local planning officials, cost was a major determinant in the overall design. The target was a system that costs less than $25 000 for all hardware and software. Ease of use is especially important with agencies that can not afford specialized computer personnel. This meant the creation of a simplified method of entering data and queries into the computer so that the planner does not have to worry about “command structures” and can concentrate on the problem. In addition to its low cost, another advantage of the METLAND GIS is that it is a poly-
New
gon-based system. Unlike most GIS which convert spatial information relating to soils, land use and other data into grid cells, all data is manipulated in polygon form through a network-clipping algorithm (Waltuch and Hoffman, 1986). This is important when dealing with applications such as the case study which depends heavily on the accuracy of property boundaries and their relationship to other landbased information.
CASE STUDY A case study involving the city of Westfield, MA highlights the issues relevant to the application of workstation-based GIS technology to farmland preservation as well as other land-use
England
States
nn
0 5
0’
NEW
HAMPSHIRE
MASSACHUSETTS
10
15
miles
25 kilometers
337
!02
90
Fig. 2. The location of Westfield, Massachusetts
and the distribution
decisions. The city of Westfield belongs to a group of west-central Massachusetts towns that lie in the valley surrounding the Connecticut River (Fig. 2). The city covers 47.5 square miles; its population is approximately 36 500 and growing rapidly, 13.8% between 1970 and 1980 at a time when the county lost 3.8% of its population. The purpose of the project was to assist the city of Westfield’s Department of Community Development in determining the extent and location of conflict between urban development (industrial, commercial and residential) and the city’s farmland (a “city” in Massachusetts can encompass non-urban land since all land is part of an incorporated unit ) . The project was unusual in that it involved cooperation between the city of Westfield, the USDA Soil Conservation Service, the Massachusetts Cooperative Extension Service and the MET-
of farm parcels within the city.
LAND research team. The project also fulfilled the ideal of being a participatory project which centered around a volunteer farmland advisory committee which assisted in the development of questionnaires and data collection. The objectives The four major objectives of the project were to provide the City with methods to: ( 1) determine what areas of Westfield contain important farmland under active agricultural use; (2) determine which areas of the city are most suited for development; (3 ) assess the degree of conflict between agriculture and development in the city; (4 ) identify farm parcels that meet the criteria for the Massachusetts Agricultural Preservation Restriction (APR) Program, a state-
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funded program that allows selected farmers to sell their development rights to the state at fair market value. Data sources
The first step in the process was the formation of a farmland advisory committee composed of farmers, developers, city board members and other citizens concerned with the future of Westfield’s farmland, all of whom participated in setting the direction of the committee. An extension service specialist was the group’s coordinator, 2 METLAND researchers served as liaisons to keep the cominformation informed about mittee METLAND was gathering and an SCS planner provided important input to the project. All listened to the farmers’ ideas about farmland in the city. The farmland advisory committee developed a questionnaire and conducted a survey of Westfield farmers in order to gather detailed information about individual farm parcels. Farmland is scattered throughout the city, with approximately 152 farm parcels in Westfield totaling 5594 acres, 18.5% of the total land area. Surveys were returned by 18 dairy, 6 beef, 7 hay, 6 vegetable, 3 fruit, 2 livestock, 3 forestry, 1 orchard and 2 other farmers, reporting on 4 012 acres of land. A majority of the nonresponding “farmers” were absentee landowners. Maps of Westfield were digitized and entered into the computer. This information included data on soils, land use/land cover, flood plain, surface zoning, 1% probability water, roads and railroads, slope, existing sewer and water lines and farmland parcels. ASSESSMENT
PROCEDURES
To determine the actual conflict that existed between agriculture and urban development, it was necessary to assess the land’s inherent productivity, development pressures that were
impacting the City of Westfield and development suitability issues which could aid the city to find alternative non-agricultural land for development. To accomplish this, 5 assessment procedures had to be developed, one for each of the following categories of land potential. An assessment procedure can be defined as the quantification of resource values for certain use potentials. ( 1 ) Agricultural productivity potential. (2 ) Municipal/administrative forces - development pressure according to zoning, public utilities and other municipal/administrative forces. (3) Commitment to agriculture - development pressure according to farmers’ commitment and external forces. (4) Physical development suitability. ( 5 ) Flood plain hazard areas. Agricultural productivity potential
A 3-step procedure was used to determine the agricultural productivity rating for any given area of land. First, the 270 soil types and classes were aggregated into 5 soil suitability groups, according to a modified version of the Land Evaluation System (LESA) developed by the Soil Conservation Service of the U.S. Department of Agriculture. The modifications were necessary since the LESA system is biased towards “in-ground” crops, such as vegetables, and soil suitability was determined according to its ability to support these crops. However, Westfield’s farmland is characterized by only 9% vegetable crops and 18% silage corn. Most farmland in Westfield (73%) is used for dairy, beef, orchards and other forms of agriculture. Second, the degree to which current land use detracts from soil suitability was considered. The 104 land-use types (MacConnell, 1975) were aggregated into 5 groups based on relative impact of land use on the agricultural productivity of the soil (Fabos and Caswell, 1977 ). For example, a parcel of land with excellent agricultural soils that was covered with
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housing is very unlikely to be put back into agricultural production. The degree of detraction is expressed as the cost of restoring the land from its current use to productive agricultural use. The computerized land-use map was used to group land uses and to store an aggregated map of the land according to these detractor ratings. The final step involved an overlay of the aggregated soil suitability and detractor maps, and determination of high to low agricultural productivity ratings. The final agricultural productivity assessment map was produced on the computer, with ratings of AA, A, B, C or D assigned according to the combined values of soil suitability and land use (Prince, 1985 ). Municipal/administrative
forces
The first of 2 assessments of development pressure was developed specifically for this study. It involved the use of spatial and municipal/administrative data. This procedure involved the rating of land parcels for 5 factors that contribute to the conversion of farms to non-farm use: ( 1) proximity to public utilities - sewer and water lines; (2) adjacent land use - percentage of land in agricultural use with a 0.25 mile radius of the parcel; ( 3 ) zoning of the farm parcel - agricultural or open space, industrial/commercial or residential; (4) the tax classification of the farm parcel whether or not it was assessed with a differential property tax based on the parcel’s agricultural use; ( 5 ) proximity of the farm to improved roads. Each factor was rated A, B or C, in decreasing order of the pressure on a farmer to sell land to a developer. Commitment
to agriculture
The second assessment of development pressure evaluated the farmer’s current and fu-
ture commitment to agriculture based on three questions from the farmer survey: ( 1) the number of years the farmer intended to continue farming; (2) whether or not there was a family member or other interested in continuing the farm operation; (3) the number of offers the farmer has had for purchase of his land in the past 5 years. Physical development suitability
The assessment of physical suitability for development was based on earlier METLAND procedures (Fabos and Caswell, 1977) to determine the cost of development. This procedure assessed 5 soil characteristics: depth to bedrock, depth to water table, drainage, slope and quality of topsoil. Each of the soil characteristics poses its own limitation on development and there was an associated cost involved to overcome that limitation. For each soil type, the costs for overcoming each limitation are added and rank ordered in tabular form, then displayed spatially on the screen or printed out. This list of development costs was attached to the soils data base and was used to aggregate the soils spatially. A very low rating for development suitability does not preclude development from taking place. It indicates that the cost for developing the parcel will be quite high and assumes a developer will look for a site that has fewer restrictions, thus reducing costs. Flood hazard
Many areas, especially good farmland located near rivers, are prone to flooding. The flood hazard assessment served to identify lands within the 1% probability flood plain. It is important to restrict or limit the amount of development within the flood plain to minimize damage and prevent the loss of life associated with major floods.
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APPLICATION
OF ASSESSMENTS
The 5 assessment procedures were developed for a series of specific applications, of which 2 are described. The first determines the degree of conflict between agriculture and development and where that conflict is occurring. This procedure uses the flood plain and development suitability assessments along with the farm parcels map to assess the conflict. The second application discusses how this information can be applied to a specific planning issue once the conflicts are determined. This application uses all 5 assessments. The application of these assessments links the community planner’s values, knowledge and judgement with the tremendous data storage, manipulation and display capabilities of the workstation-based GIS (Lindhult and Waltuch, 1985). Identifying conflicts between agriculture and development To make any attempt at preserving farmland and finding appropriate locations for development that do not conflict with agricultural activities, the planner must first identify where potential conflicts exist and the extent of those conflicts. Without a clear understanding of this information, it is difficult to make appropriate land-use decisions. In the case of Westfield, the first step was to identify what parcels enjoyed limited protection from the flood plain. Westfield has two large contiguous areas of flood plain adjacent to the Westfield River (Fig. 3 ). An overlay map was generated of the flood plain and farm parcels which showed that 13 individual farm parcels have at least 50% of their land area within the flood plain. Throughout the rest of the city the flood hazard line passes through all or part of 29 additional farm parcels. This means that 42 of the 152 farm parcels in Westfield have limited protection due to restrictions on development within the flood plain. The total
acreage comes to 540 acres or 10% of the total farmland. This figure can be somewhat misleading in that a developer can still purchase a parcel and only develop on upland areas away from the flood plain, thus removing the parcel from agricultural use. The remaining 90% of Westfield’s farmland is still available for potential development. The next step was to overlay farm parcels with the physical development suitability map. Areas of potential conflict between agriculture and development became quite obvious. The prime or least-cost class ( 1 out of 4) for development constituted an area of 8860 acres in Westfield, of which 1926 acres lie on farmland in parcels ranging from 1 1 to 300 acres. The 1926 acres are 22% of the prime developable area and 35% of the farmland. The three classes ( 1, 2 and 3 that do not pose severe development restrictions cover a total of 1 1 783 acres of which 3667 acres (31%) are in active agriculture. This leaves 8 116 acres available for development. These results indicate that Westfield has abundant land available for development without using the current farm parcels (Fig. 4). Although this is a lot of land, one must not give in to the assumption that no problem exists. Agricultural land is an attractive commodity to developers since it is typically in a large block, thus reducing the need for assembling several different parcels. The GIS allowed the planner to identify where the best developable land is in Westfield and how it relates to the location of active farm parcels. This allowed various strategies to be formulated about how development could be directed to prime developable areas located away from agricultural land. Decisions such as the placement of proposed sewer lines greatly impact the future of farmland. Fifty-five percent (55%) of Westfield is zoned for agriculture while only 18.4% is in active agricultural use. What is needed is a rezoning effort which considers this large block of land relative to its development potential and which designates appropriate uses.
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Kilometks
Fig. 3. The location of the flood plain in relationship to the farm parcels.
The procedure for determining the degree of conflict between agriculture and development appears extremely simple and straightforward. However, one must consider that none of the assessments is written in stone. Interest groups and individuals may desire to modify these assessments, thus changing the results. This is where the workstation-based GIS excels. Instead of working for days to prepare a new map showing a group’s interpretation, the computer can quickly generate a map showing the spatial distribution of the results. This makes it possible to direct the discussion towards the actual differences that result from new interpretations. Specific planning applications
The application of the assessment procedures is relevant not only to the identification
of conflicts, but to other spatial planning problems as well. The Massachusetts Agricultural Preservation Restriction Program (APR) illustrates this process. APR is a highly competitive program that gives preference to protecting those farms which are facing imminent development pressure. To determine which farms are potential candidates for this program, the following APR criteria were entered into the computer: ( 1) to look for the farms with the highest agricultural potential; (2 ) to see which farms were under the highest in terms of proximity to pressure infrastucture; (3 ) to estimate the likelihood of a farmer or his heirs continuing the agricultural use of the land; (4) to see which parcels were highly suitable
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Excellent Good Acceptable Poor Downtown Westfield
L/q Fig. 4. Development
1
2 Kilometers
suitability ranking for soils in Westfield.
for development and therefore likely to be targets of developers; (5) to see what areas are already indirectly protected because of flood plain development restrictions. By applying the 5 assessment procedures, a map was generated illustrating which farms most closely fit the APR criteria and thus had the greatest potential for receiving state support. The workstation-based GIS can only identify parcels that meet the user-specified criteria; it is not designed to take into account political judgments that are intuitive to a planner. The computer’s main use is to substantially narrow down the likely parcels, in this case 152 to 3, so that a community can focus educational efforts about farmland protection towards those farmers who face the greatest pressure. This type of procedure relieves the
planner of the tedious and time-consuming task of evaluating all land parcels against a program’s criteria. CONCLUSION Workstation-based GIS is expected to be used in the near future by local planners to generate land-use scenarios that will identify where development should occur in order to protect valuable agricultural resources. Planners will be able to utilize this tool to quickly avail themselves of current information. In place of the limited application of information used in similar types of situations, the computer permitted us to use 5 relevant data sets and combine them to produce composite assessments. Using the workstation-based GIS, the plan-
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ner can develop more sophisticated techniques of assessing information rather than relying on simplistic procedures necessitated by manual labor. Information can be combined in a multitude of ways and in a short period of time, allowing the planner and the public to evaluate a larger number of potential alternatives to planning problems. Planning is a learning process and decision making involves many players. The workstation-based GIS can articulate the decision making by mapping out alternative plans for each interest group or individual. The benefit is the ability to add meaningful public participation; where an idea, opinion or answer to a question can be expressed spatially, the pros and cons of each alternative can be evaluated against environmental and cultural criteria. It was found that one of the major benefits of the GIS to the city was as a cartographic tool. As in most communities, the 8 major maps used by the Department of Community Development were at 6 different scales, making it impossible to overlay maps to extract information. The establishment of a computerized geographic data base resolved this through digitizing the maps, putting them into digital form, which allowed the maps to be plotted at a common scale for simple manual overlays. The protection of farmland must be integrated into a comprehensive planning process that evaluates all land-use decisions in a community. The workstation-based GIS provides planners with a tool to run a series of land-use scenarios and evaluate their spatial consequences. This can only bode well for the protection of our valuable farmland resources.
REFERENCES Fabos, J. and Caswell, S.J., 1977. Composite Landscape Assessment. Research Bulletin No. 637, Massachusetts Agricultural Experiment Station, University of Massachusetts at Amherst. Gross, M., Bucko, D., Fabos, J. and Foster, J., 1984. Landscape Planning and Evaluation: A Combined Goal-oriented and Benefit Loss Approach. Research Bulletin No. 692, Massachusetts Agricultural Experiment Station, University of Massachusetts at Amherst. Hendrix, W. and Smith, G., 1985. The application of geographic information system technology for resource management and landscape planning. Proceedings from Landscape/Landuse Planning Session, American Society of Landscape Architects Annual Meeting, pp. 38-46. Jeffords, J.M., 1984. The loss of U.S. cropland: whose issue is it? In: F.R. Steiner and J.G. Theilacker (Editors), Protecting Farmlands. AVI Publishing Co., Westport, CT, pp. 3-14. Keene, J., 198 1. Executive Summary, Loss of Valuable Agricultural Land, The Problem and Its Causes. In: R.E. Caughlin and J.C. Keene (Editors), National Agricultural Lands Study; The Protection of Farmland: A Reference Guidebook for State and Local Governments. U.S. Government Printing Office, Washington, DC. Lindhult, M. and Waltuch, M., 1985. Workstations on the cutting edge of landscape planning. Proceedings from Landscape/Landuse Planning Session, American Society of Landscape Architects Annual Meeting, pp. 47-54. MacConnell, W.P., 1975. Remote Sensing 20 Years of Change in Massachusetts I95 l/2-1 97 l/2. Research Bulletin No. 630, Massachusetts Agricultural Experiment Station, University of Massachusetts at Amherst. Prince, N., 1985. Farmland preservation in the city of Westfield, MA: a computer-aided planning approach. Unpublished Masters Project. U.S. Department of Agriculture, 1983. National Agricultural Land Evaluation and Site Assessment (LESA) Handbook. USDA Soil Conservation Service, Washington, DC. Waltuch, M. and Hoffman, J., 1986. MAPLE: A workstation based GIS for landscapes and the environment. Proceedings from Landscape/Landuse Planning Session, American Society of Landscape Architects Annual Meeting, pp. 72-76.