This data set contains polygons representing the groundwater discharge areas for the 14 hydrographic areas in the middle Humboldt River Basin, north-central Nevada.
These data represent the extent and spatial distribution of irrigated acreage delineated from maximum Normalized Difference Vegetation Index (NDVI) derived from Landsat scenes in the Walker River Basin, California and Nevada, at five-year intervals from 1975-2010. The field boundaries in this data set are digitized from one-year composite maximum NDVI data derived from atmospherically corrected Landsat 2 Multispectral Scanner (MSS), Landsat 5 MSS, and Landsat 5 Thematic Mapper (TM) scenes. NDVI was calculated from the corrected reflectance data for each selected scene during the growing season (May through early October) and a single, composite image of maximum NDVI values was derived for each 5-year interval. Selecting...