Bathymetry data from repeated surveys of a submerged nearshore berm at the mouth of the Columbia River, Washington, 2020-2021

Previously unpublished bathymetric data were acquired by the U.S. Army Corps of Engineers, and released here with the permission of the USACE. Bathymetric surveys were performed using the survey vessel Elton equipped with a Reson SeaBat T50-P mulitbeam sonar operated at 400 kHz. Depths were computed with sound velocity measurements acquired with either a YSI CastAway CTD or AML X2 Series sound velocity profiler. Positioning was achieved with an Applanix POS-MV Wavemaster II and submersible IMU operating primarily in real-time kinematic mode with differential corrections transmitted via NTRIP from the Oregon Real Time GNSS Network (https://www.oregon.gov/odot/ORGN/Pages/index.aspx). Post-processed positions were applied using Applanix POSPac MMS software when real time communications between the survey vessel and geodetic network failed. Hypack hydrographic software was used for survey data acquisition and post processing. Elevations relative to mean lower low water (MLLW) were computed using offsets from the National Geodetic Survey Geoid12a geoid model and tidal datum established at Hammond, Oregon.

Original data were re-projected using UTM Zone 10, meters coordinate system and elevations were converted from survey feet to meters. Processed bathymetry data from each survey were gridded onto a using bin averaging onto a regular grid with 5-m resolution.