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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />sort, separate, and save the individual points into distinct cross sections in separate tab delimited <br />text files that could then be opened as a new view in ArcView, A Macro is a series of commands <br />and functions that are stored in a Microsoft Visual Basic module and can be run whenever a <br />specific automated task needs to be performed, The use of a Macro can significantly save time <br />when the same operation will be repeatedly performed, The program that was written is given in <br />Appendix B, For each cross-section, the lowest elevation point was extracted and saved in one <br />tab delimited text file to be used as the points for the river centerline in ArcView. <br /> <br />The GPS tab delimited text files were added into the ArcView "Tables", which were then added <br />to the view with "Add Event Theme," Using the X-tools ArcView extension, created by Mike <br />DeLaune of the Oregon Department ofForesty, the separate cross-sectional points were <br />converted into polylines, which were then merged into one file containing multiple polylines, <br />The centerline points were added to the "Tables" in ArcView and added to the view with "Add <br />Event Theme", The points were made into a poly-line that designates the centerline of the river <br />reach, The view was then projected into an appropriate coordinate system with the appropriate <br />map and distance units. The selection of the coordinate system and units was made based on the <br />geographic location of the study area, the coordinate system of other GIS data, and the desired <br />units of the data. The merged theme of the cross sections was then converted to a shapefile, <br />saving the shapefile in the projected units, <br /> <br />A Triangular Irregular Network (TIN) was then created from the other GIS data using contours <br />as mass points for the elevation, and the merged cross-sectional polylines and the centerline <br />polyline as hard brake lines, The TIN was created to assign elevations to each point, The HEC- <br />geoRAS ArcView extension, created by the Army Corps of Engineers Hydrologic Engineering <br />Center, was then used to create an export file that could be imported into HEC-RAS, The HEC- <br />geoRAS extension also required the 3D Analyst ArcView extension to function, A streamline, <br />cutlines, flowlines, a 3D stream centerline, and 3D cross section lines were created from the <br />preRAS menu created by the extension and a RAS GIS file was created that was ready for <br />Hydraulic Analysis using HEC-RAS, For further information on the HEC-GeoRAS ArcView <br />extension refer to the HEC-GeoRas User's Manual, <br /> <br />13 <br />