1. A A v beam v ship v ship = v beam / sin( A ) Doppler log - ship’s speed using the Doppler effect. ADCP extends this idea to calculate water speed relative to the ship at different depths below the hull. Knowledge of the ship’s speed over the seabed then allows calculation of the water current profile relative to the seabed. Acoustic Doppler Current Profile (ADCP) See: http://www.rdinstruments.com/index.htmlhttp://www.rdinstruments.com/index.html Basic principle: v ship

2. ADCP - moored on seabed, looking upward, battery-powered, internally-recording. ADCP - attached to moving vessel, mains-powered, communication with pc, bottom-tracking..

3. Carry out a cross-estuary transect to measure the along-estuary water flow. Points to consider: What is the depth of the first good velocity measurement? How close to the estuary bed is the last good measurement? What angle does the main estuary axis lie at relative to north? How much of the shallower margins of the estuary are missed in the transect? What stage of the tide are the measurements taken? What is the average flow likely to be, compared to the typical tidal velocities seen during the transects?

4. Data analysis. Data collection using WinRiver - Acquire Produces RDI binary data files. Data playback and ASCII output using WinRiver - Playback Produces readable ASCII text files with headers Transect velocity calculations using ADCP_process Produces ASCII text files, columns of data suitable for typical graphics packages.