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5 about the river corridor were recorded on audio channel #1 of the red-band videotape. A time code was recorded on audio channel #2 and as a banner on the green-band tape. This time code was used to retrieve synchronized video frames from each of the videotapes to construct three-band composite images. Other information was recorded as a banner on the red-band tape, including latitude and longitude position from a global positioning system, airplane altitude, ground speed and direction, date, and time of day. Videography was collected on five dates from May 15 to June 5, 1992, by flying about 2,000 ft above the river surface at each study site. Videotaping at this altitude provided an image resolution of 0.5 to 1.0 in per pixel and typically kept both shorelines and riparian vegetation in the fields of view of the cameras. Because of the meandering river channel, weather conditions, and topography, several flightlines were required to videotape each study site. During videography, releases from the dam ranged from approximately 800 to 4,000 cfs. Immediately prior to the first videotaping session, field crews visited each study site to collect site-specific information and to place panel markers that would be used to provide scale measurements during analysis of the imagery. Information gathered included descrip- tions of each site, shoreline substrate, and measurements of features likely to be visible in the videography. The scale markers, which consisted of 6.6-ft x 6.6-ft (2-m x 2-m) white plastic panels, were placed approximately 33 ft (10 m) apart near the shoreline. Photographs and narrated videotapes were also collected at each site to show positioning of the markers and other features of interest, such as vegetation and topographic features. After videography was collected, images were catalogued to identify river segments that had been videotaped at three or four different flows, including the highest and lowest flows. The number of flows at which a particular site was successfully videotaped depended, in part, on weather conditions (e.g., cloud cover) during data-collecting flights. After these segments were identified, the appropriate images were captured and transferred to a computer format by using commercially available hardware and software. Further details of videoprocessing are discussed by Snider et al. (1994). The upper boundary of the riparian zone was identified on the low-flow images, and the images were trimmed along this boundary to reduce the overall size of the image and the amount of disk storage required for each image (Figure 4). Total area and area of water in acres were then determined for each image. Area above water and area above the 800-cfs level were calculated from these values, and the relationships to flow were determined for each study area.