Bathymetric Data Collection for Post-levee Repair in the Green River near Tukwila, Washington on 20160512

Field Data The third ADCP data collection effort for this project was done on May 12, 2016 represented by these bathymetric point locations on the Green River near Tukwila, WA . The stream surface in the vicinity of the project area was flat and water clarity was good. The upstream and downstream extent of the fishing site was identified by the Muckleshoot’s fisheries biologist Martin Fox to correspond with the tribes’ traditional fishing location. Reverse flow was first observed immediately along the right bank at the upstream end of the fishing site where the channel width slightly increases. This area of reverse flow persisted for approximately 2 meters downstream where uniform flow returned across the stream channel. A total of 29 cross-sections were surveyed with the ADCP. The uppermost cross section was surveyed one meter above the riprap bank geometry change. Each successive cross section was approximately one meter downstream from the previous. The most downstream cross section was surveyed where uniform flow was observed across the entire stream channel width. Processed Data USGS provided the mean surface water elevation (or mean stage) as reported for the real-time steamgaging station No. 12113344 approximately 11 river miles upstream of the project surveyed site. The mean stage was estimated over the time period of ADCP data collection for this dataset and was used as the reference elevation for calculating the bed-elevation point data. Latitude, longitude and water depth were exported from the ADCP instrument using VMT (The Velocity Mapping Toolbox), a processing and visualization suite for moving-vessel ADCP measurements (Parsons, D.R., et al., 2013). These data are presented in the accompanying spreadsheet (GreenRiverBathymetry_20160512.csv) where the bed-elevation of the river bottom was calculated by subtracting the measured depth from the mean stage.

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