Rich Hall
MD Office Of Planning
301 W. Preston Street
Baltimore, MD 21201-2362
RICH@mail.mop.md.gov
The Office of Planning has developed an innovative approach for integrating watershed protection and growth management. The objective is to integrate decision-making for growth management, preservation of resource lands, and nonpoint source pollution control. To accomplish this we have developed a series of geographic information system (GIS) based models, collectively called the Watershed Planning System (WPS). The WPS provides a framework for gathering, analyzing, and interpreting environmental information at a resolution necessary for addressing growth and ecological considerations inherent in making land management decisions at local and regional scales.
The three GIS-BASED models of the WPS provide the tools needed to tailor land use planning and development to landscape conditions and management (Figure 1). It has also been designed to work at the watershed scale to allow local management objectives and decisions to be linked to broader regional objectives.
The Baseline Inventory Model provides an inventory of existing land uses and nonpoint source (NPS) pollution management practices with respect to nutrient loads generated from the landscape per source category. An evaluation of the effect current management can have on nutrient loads is included as part of the Baseline Inventory. Data compiled from NPS management programs, research, monitoring, and modeling are then used to estimate the Baseline Inventory (OP, 1993; OP, 1994b). For each source category the Baseline Inventory estimates the relative pollution loads; the effects of existing management systems and pollution buffers (forest and wetlands); and the loads from reaching surface waters.
The Growth Management Simulation model projects the existing land inventory into a series of possible "future" landscapes as a function of population and household projections and different land use management alternatives. Changes in land uses and environmentally sensitive areas are estimated using population projections and growth management factors as independent variables. The model evaluates different possible land use scenarios by changing assumptions about individual county comprehensive plans, zoning plans, sewer service, subdivision and environmental regulations, etc. New development is then calculated as a function of household demand, existing or hypothetical management choices (such as, clustering, transfer of development rights, growth areas, and agricultural land preservation), and user-defined considerations. User-defined considerations allow local concerns and policies that may influence the type and locations of development to be represented in the model. This allows different land use scenarios to be evaluated by changing assumptions associated with zoning, subdivision, and environmental regulations.
The Nonpoint Source Management Simulation model estimates the potential impacts of NPS management alternatives (urban and agricultural BMPs) on NPS loads when applied to current land use conditions (Baseline Inventory) and to possible future land use conditions (Growth Management Simulations). The model allows the user to evaluate the relative values of NPS management alternatives under various land use patterns and the importance of the land use alternatives. Thus, a county proposing to use different stormwater management practices can examine the effects on pollution for different possible planning and zoning schemes (such as, traditional versus clustering land use patterns). The effects of stormwater management alternatives can be reviewed in relation to different land use patterns and other NPS controls, such as agricultural controls or pollution buffers. The result is a comprehensive set of information for watershed planning and decision making.
The key utility of the Watershed Planning System as a planning tool is its ability to readily represent realistic alternatives and management programs. The management scenarios represent the effects of traditional and innovative BMPs, and land management tools. This approach can be applied in any part of the State because the models use standardized GIS layers to characterize important features. The models can also be customized to use more detailed data, where they exist. The requirements and constraints of State and local plans, programs, and regulations are used in the models to determine the potential for development and conservation of resource land and sensitive areas in each (sub) watershed. Following coordination with local jurisdictions and State and local programs, the alternatives evaluated through the models represent feasible program and BMP options.
The WPS system provides a framework to evaluate the ability of an area to accommodate growth by the area's physical capacity to accommodate development; the limits of existing wastewater and water supply infrastructure; and the resource management objectives for the watershed. Land management planning must be designed to ensure that adequate resource lands remain to meet resource management, forestry, agricultural, and water quality goals established for the watershed. The WPS provides a proactive approach to ensure that watershed and resource protection support growth by evaluating development based on the watershed's capacity to sustain development.
To date, the WPS has been applied in the Patuxent River Watershed (OP, 1994c) which covers parts of seven counties, Piney and Alloway Watersheds in Carroll County (OP, 1994b), and in Winter's Run in Harford County (OP and Harford County, in preparation).
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