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<br />. <br /> <br />. <br /> <br />Two points were used for registering the photograph in space while the <br />other two or three points were used as controls to determine the accuracy <br />of the objects relative to the USGS maps. Over thirty control points were <br />established per photo series. <br />After digitizing was completed, the ACAD files were exported into <br />ARC INFO for further analysis. ARC is a "state of the art" vector based GIS <br />system which is well adapted for the analysis of changes in a linear system <br />such as a river. Measurements of island area, in-channel water surface <br />area, and side channel/backwater area were made on a mile by mile basis <br />throughout the study reach. This mile by mile approach allows the <br />analysis of both site specific changes in potential fish habitats as well as <br />summaries for the entire 32 mile reach. <br />Estimates in the precision of this technique were made by re- <br />digitizing photographs and comparing these area measurement results to <br />the original results. This gives a measure of the error involved in both <br />digitizing and photograph interpretation. <br /> <br />. <br /> <br />. <br /> <br />, <br /> <br />, <br /> <br />, <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br />