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-,---_..~~".--.-....................:,_..~=,-~--- . 7 3,000 ft, the Ikigami camera produced imagery with a pixel size of 1.2 m. The video images were analyzed on a Club American 386 microcomputer system which included an Everex Vision 16 video capture board, an Electrohome color monitor, and a Hewlett-Packard PaintJet printer. The video images were transferred to I/2-inch VHS tape from 3/4-inch tape prior to analysis. Analysis was performed with Map and Image Processing System (MIPS) software. Video images were viewed on the color monitor and captured at appropriate intervals to provide overlapping scenes. The images were then annotated with date, site, rm, and an approximate north arrow and saved on hard and floppy disks. Absolute scale was calculated at Island Park with two panels on Buck Island placed 200 ft apart. For Jensen, the video scale was determined from the separation of road and building features identifiable on the 1:24,000 scale USGS topographic map. The outlines of backwaters were traced using a cursor controlled by a mouse and creating short line segments on the image in a manner similar to those digitized by photographic/GIS analysis. The area was calculated by MIPS software and annotated into a copy of the image. Backwaters were shaded solid blue. Both the original video frame and the annotated version were saved on hard and floppy disk and 9-track tape to record the interpretation. Three analyses were made with the data: (1) Compare differences in backwater area and numbers at the Island Park site as calculated by photographic/GIS and videography/MIPS techniques performed independently by different interpreters, (2) Compare backwater area calculations derived from each technique using the aerial photography previously interpreted from the Jensen site for reference while delineating areas on the video display screen. The area of 34 backwater polygons that were identifiable on the photography and videography was calculated and compared. This procedure compared area calculations for each technique, (3) A comparison between backwater area calculated from the September video acquired at Island Park (912 ft3/s) and backwater area as predicted from the 1987 aerial photography study linear regression equation for this site. Although the comparison between calculated and predicted backwater area is indirect, it is another indication of the similarity of photography/GIS and videography/MIPS techniques. RESULTS 1986 Study The acreage summaries for all interpreted classes at Split Mountain are given in table 1. Backwater area steadily increased as flow was decreased, from 1,659 m' (448 m'/mHe) at 4,359 ft3/S to 3,480 m' (~1 m'/mi~eJ at 3,119 ft3/s to a~of 4,087 m2 (1105) m2/mile).!i L889 ft3_~) Backwater numbers varled from 3 at the two higher flows to 18 at 1,889 ft3/s. Backwater availability at Our~ varied from the other sit table 2). Maximum backwater ~ occurred at the highest flow 4, 59 ft /s) with