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<br />Initial land-use and land-cover classes that were selected are listed in <br />table 3. A two-dimensional plot between landsat bands 5 and 7, which illus- <br />trates the ellipses for all land-use and land-cover classes, is shown on fig- <br />ure 11. All combinations of the four Landsat bands were evaluated. Based on <br />the amount of overlap of spectral signatures between the urban classes and <br />the dryland agriculture and rangeland classes (fig. 11), it was decided to <br />delete the two urban classes. As discussed earlier, urban centers in the <br />basin are relatively small; downtown areas contain gravel and dirt lots, and <br />residential areas generally include a large proportion of grass and trees. <br />These factors make the urban areas spectrally similar to other classes on the <br />summer imagery. <br /> <br />Table 3.--Initial land-use and land-cover classes selected for <br />classification using the Interactive Digital Image Manipulation System <br /> <br />Class number <br /> <br />Class <br /> <br />1---------------------- <br />2---------------------- <br />3---------------------- <br />4---------------------- <br />5---------------------- <br /> <br />6---------------------- <br />7---------------------- <br />8---------------------- <br />9---------------------- <br />10---------------------- <br /> <br />11---------------------- <br />12---------------------- <br />13---------------------- <br />14---------------------- <br />15---------------------- <br /> <br />Urban. <br />Dry1and agriculture 1. <br />Dryland agriculture 2. <br />Urban residential. <br />Dryland agriculture 3. <br /> <br />Rangeland 1. <br />Rangeland 2. <br />Cottonwood. <br />Wet meadow. <br />Water. <br /> <br />Rangeland (sparsely vegetated). <br />Ba re so i 1 . <br />Deciduous vegetation. <br />Mixed grass and brush (wet areas). <br />Meadow. <br /> <br />The 16 classes selected for the final land-use and land-cover classifi- <br />cation are listed in table 4. A two-dimensional plot between landsat bands 5 <br />and 7, which shows the ellipses for the final land-use and land-cover class- <br />es, is shown on figure 12. Several classes show some overlap of spectral <br />signatures; for example, the signatures of cloud shadows (class 16) and water <br />(class 8) (fig. 12). Considerable overlap also is apparent for the signa- <br />tures for cottonwood (class 6) and other deciduous trees (class 11). Cotton- <br />woods are deciduous trees; however, they are in a class of riparian vegeta- <br />tion which would be desirable to separate as a unique class. Lesser degrees <br />of overlap occur for rangeland (brush and shrub) and cottonwoods, mixed grass <br />and brush (wet areas) and cottonwoods, and rangeland (sparsely vegetated) and <br />dryland agriculture 2. The overlap of signatures between cloud shadows and <br />water posed no major obstacle to the analysis because few clouds were pre- <br />sent in the image, but these could be a factor in images containing a large <br /> <br />22 <br />