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APPLICATION OF LAND-COVER DATA FOR ENVIRONMENTAL ASSESSMENTS
Citation:
Wickham, J D. APPLICATION OF LAND-COVER DATA FOR ENVIRONMENTAL ASSESSMENTS. Presented at Land cover Map 2000, Monks Woods, United Kingdom, November 1, 2002.
Impact/Purpose:
The objective of this task is to produce land-cover and related products that are needed to meet Annual Performance Goals (APG) under GPRA Goals Clean Air, Clean Water, and Healthy and Safe Communities, and to meet the critical needs of EPA Regional Offices.
Description:
In many parts of the United States, urbanization is a pervasive dynamic that has many environmental consequences. Land-cover and related (e.g. Landsat) data are fundamental for studying urbanization itself and its environmental effects.
Well established models in economic geography are useful for forecasting where urbanization is likely to occur in the future, and these forecast can be used in turn to evaluate environmental consequences of urbanization. Economic geography models include retail gravity, rent theory, population decay, and von Thunen. All of these theories share a common framework for identifying the relative location of economic activity on mass (e.g., population) and distance. Using GIS, it is possible incorporate the concepts of mass and distance to create modeled surfaces of land demand, and evaluate these surfaces relative to land-cover change and the spatial pattern of natural resources. For the southside economic region of the state of Virginia, USA, we modeled splined surfaces of land demand and correlated these surfaces with NDVI-based land-cover change and estimates of forest fragmentation. All expression of splined land demand show significant correlation with estimates of forest fragmentation (0.543 - 0.71 1) and NDVI-based land-cover change (0.924 - 0.945). The relationship between NDVI-based land-cover change and land demand surfaces was also examined at the larger, regional scale of the mid-Atlantic states, and showed similar correlations (0.76 - 0.97).
Changing land-cover patterns also affect export of nutrients (Nitrogen M, phosphorus [PI) from watersheds. We development a model of nutrient export risk to examine land cover - nutrient export relationships. Evaluation of watershed nutrient export risk as a function of land-cover composition (proportion of forest, urban, and agriculture) revealed that N and P export risk was nonlinearly related to the proportion of forest in the watershed and increased significantly when the proportion of forest dropped below about 85 percent. We also linked the nutrient export risk model with a model of forecasted urbanization to identify which localities across a broader region were most vulnerable to increases in nutrient export risk as a result of future (forecasted) urbanization. For a locality to be identified as vulnerable, changes in nutrient export risk had to be greater than accumulated uncertainties in the nutrient export and urbanization models. As a result of the vulnerability analysis, 43 localities were identified as vulnerable to increased N export and 3 85 localities were identified as vulnerable to increased P export. The majority of localities vulnerable to increased N export drained to the Gulf of Mexico and the majority of localities vulnerable to increased P export drained to the Atlantic Ocean.