Abstract |
Land use data were determined using several methods, including (1) Geographic Information System (GIS) map analysis, (2) analysis of topographic maps, (3) analysis of town property tax maps and tax data, (4) analysis of aerial photographs and (5) groundtruthing. Much of the undeveloped land use area (i.e., forest, wetland, grassland) was determined using a GIS layer which is a combination of Maine Gap Analysis (GAP) landcover and USGS Multi Resolution Landcover Characterization (MRLC) landcover layers. It was created at the request of Maine DEP Bureau of Land and Water Quality (BLWQ) staff. It includes those classes in each layer which are best suited to calculating impermeability of watersheds. Both MRLC and GAP (and so Maine COMBO) are based on 1992 Landsat imagery. The developed land use areas were obtained using the best possible information available through analysis of methods 2 through 5 listed above. |