MODELING URBAN AND EXURBAN DEVELOPMENT IN RESPONSE TO LAND-USE DECISIONS ON PUBLIC LANDS

Land-use policies on public lands can influence social, economic, and demographic properties of adjacent towns and cities, and mediate rates and patterns of urban and exurban development. Gateway communities in proximity to the extensive lands administered by the Bureau of Land Management (BLM) in the western U.S. are especially sensitive to federal oil/gas and renewable-energy development policies. Recognizing this, the Grand Junction, CO, BLM field office has proposed to use community-growth forecasts of different land-use strategies (energy development vs. conservation emphasis) to assess alternatives in the resource-management planning process. To assist in this assessment, we developed a model to simulate the dynamics of urban and exurban development that uses agent-based modeling concepts to integrate socio-economic, demographic, and human preferences with biophysical features of land-uses on public lands. The model was developed specifically for the Grand Valley region of Colorado, and uses readily available land parcel data to determine sub-division potential of residential and agricultural land types. Each land parcel is additionally attributed with key biophysical features such as distance from roads and average percent slope. Annual housing needs are driven by regional socio-economic factors, local socio-economic factors that are influenced by BLM land-use decisions, and human life-cycle stage of existing and new households. Location of housing developments is determined by three factors: Potential attractiveness, accessibility, and housing density of focal and neighboring parcels. Potential attractiveness is scored from viewshed assessments of scenic natural features and of proposed land uses on surrounding BLM lands. Accessibility is based on the minimum distance from roads. These three factors are weighted according to preferences of household agents, where an agent represents the socio-economic and life-cycle stage of existing or new households. Historic trends in numbers and types of household agents and preferences of agents can be estimated from retrospective assessments and used in future forecasts. These properties also can vary temporally in response to projected variation in socio-economic drivers, and based on different assumptions about how these drivers influence human demographics and housing preferences. The model outputs annual projections of numbers and acreage by residential and multifamily housing types, acreage of remaining undeveloped lands such as agricultural lands, and maps of sub-division frequency and housing density. We are applying this model to evaluate the effects of four BLM land-use scenarios on urban and exurban development over the next 30 years in the Grand Junction BLM planning area. Scenarios include no change from the past, a balanced resource extraction (oil/gas extraction) and conservation strategy, a conservation strategy, and a resource extraction strategy. In this presentation, we provide an overview of the parcel-based land-use change model, and results of simulations for the four BLM land-use strategies.

(BLM) – Bureau of Land Management