Bathymetric Data Collection during high-flow event in the Green River near Tukwila, Washington on 20160121

Field Data: The second ADCP data collection effort for this project was done on January 21, 2016 represented with these bathymetric point locations on the Green River near Tukwila, WA. The stream surface in the vicinity of the project area was relatively flat and water clarity was fair. Stream stage (water-level elevation) was 6.83 ft. higher relative to the July 2015 ADCP data collection effort. 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 was observed for approximately four meters (0.004 km) downstream where uniform flow returned across the stream channel. Due to the relatively high stage during the January 2016 data collection, a rubberized inflatable boat (R.I.B.) with a 15 horse-power outboard motor was used to collect the ADCP data. The transects measured on this date are not exactly the same as those measured in July 2015 due to the swift water conditions. As a result, multiple overlapping transects were measured to ensure high resolution XYZ point data that would be comparable to the July 2015 data. Transects measured here included a “zig-zag” transect that traverses multiple times between the upper and lower and near right and left bank extent, two parallel longitudinal transects in the immediate vicinity of the fishing site, one longitudinal transect along the left bank, and four parallel latitudinal transects covering the upper and lower extent of the fishing site. Processed Data: USGS provided the mean surface water elevation(or mean stage) collected at real-time streamgaging 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_20160121.csv) where the bed-elevation of the river bottom was calculated by subtracting the measured depth from the mean stage. An offset was applied to each measurement point in both the July and January datasets to correct for an error discovered during data post-processing, as explained in a comment within the attached spreadsheet.

现场数据（Field Data）：本项目的第二次声学多普勒流速剖面仪（ADCP, Acoustic Doppler Current Profiler）数据采集工作于2016年1月21日开展，采集点位为华盛顿州塔奇拉（Tukwila）附近格林河的水深测点位置。项目区域周边的河道水面相对平缓，水体透明度一般。本次河道水位（水面高程）较2015年7月的ADCP数据采集工作高出6.83英尺。捕鱼站点的上下游范围由马斯基尔部落的渔业生物学家马丁·福克斯（Martin Fox）划定，与该部落传统捕鱼区域相符。在捕鱼站点上游端的右岸附近首次观测到反向流，此处河道宽度略有增加。该反向流区域向下延伸约4米（0.004千米），之后河道恢复均匀流态。由于2016年1月的数据采集期间水位相对较高，本次数据采集使用了搭载15马力舷外机的充气橡皮艇（R.I.B., Rubber Inflatable Boat）开展ADCP数据采集。受急流工况影响，本次采集的断面与2015年7月的采集断面不完全一致。为此，本次采集了多组重叠断面，以获取可与2015年7月数据集对比的高分辨率XYZ点数据。当日采集的断面包括：一条在上下河段及近左右岸区域间多次往返的“之字形”断面、两处紧邻捕鱼站点的平行纵向断面、一条沿左岸的纵向断面，以及覆盖捕鱼站点上下范围的四条平行横向断面。
处理后数据（Processed Data）：美国地质调查局（USGS, United States Geological Survey）提供了项目调查点上游约11河英里处的实时水文监测站No.12113344的平均水面高程（即平均水位）。本次数据集的ADCP数据采集时段内的平均水位经估算得到，并作为计算河床高程点数据的参考高程。纬度、经度与水深数据通过速度映射工具箱（VMT, Velocity Mapping Toolbox）从ADCP仪器中导出，该工具箱是用于移动载体ADCP测量数据处理与可视化的工具套件（Parsons, D.R.等，2013）。这些数据已整理至配套电子表格GreenRiverBathymetry_20160121.csv中，其中河床高程通过平均水位减去实测水深计算得到。如附件电子表格中的注释所述，针对2015年7月与2016年1月两组数据集的每个测点均施加了偏移量，以校正数据后处理过程中发现的误差。