Long‐term publicly available monitoring records were the original source of all data used (Figure
2, Table S1 in Supporting Information
S1). Most water level, velocity, and river discharge data were accessed from Dykstra and Dzwonkowski (2020b (
link)) and updated through May 2020. The 21 stations used in this study were labeled with the first letter representing the body of water (e.g., G:Gulf, B:bay, D:delta, R:river) followed by the along channel distance inland from Main Pass along the longitudinal transect (i.e., rkm; converted from navigational river miles). Stations not on the longitudinal axis are to the east and are noted with an E (e.g., D96 E). Data from D100 and stations landward were accessed from the USGS (waterdata.usgs.gov/nwis) while the stations seaward were accessed from NOAA (
tidesandcurrents.noaa.gov) and the Alabama Real‐Time Coastal Observing System (ARCOS;
arcos.disl.org) except for B8, which was from the USGS. Most stations had a sampling interval between 6 and 60 min.
All water levels were referenced to the common vertical datum, NAVD88 (North American Vertical Datum 1988). Current velocities were determined from acoustic Doppler current profilers (ADCP) orientated for vertical (G‐14, B23) or across‐channel (B47, D53, D100) profiles, and from a benthic acoustic stress sensor (B8). To minimize differences between collection methods for the horizontal and vertical oriented ADCPs, only bins between one‐quarter and one‐third of the upper water column were used. This vertical bin range overlaps with the index velocity of the horizontal sensors as determined by the source organization (e.g., Ruhl & Simpson, 2005 ). The primary flow axis was determined by the major tidal harmonic axis (K1 & O1) with t_tide (Pawlowicz et al., 2002 (
link)). For the Gulf of Mexico station (G‐14), the major tidal axis was in line with the shipping channel, following the longitudinal axis. Because the extensive data were averaged (described below), non‐tidal shelf circulation was not removed (e.g., inertial oscillations). While some data do not temporally overlap, all measurements could be referenced to discharge during a period without bathymetric changes in dredging or the construction of bridges or upstream dams. Specific details of data sources, length of records, and sensors used at each station is in the supplemental material (Table S1 in Supporting Information
S1).
Local ground surface elevations were taken from USGS 3DEP Lidar (USGS, 2016 , 2020 ), The Shuttle Radar Topography Mission (Farr et al., 2007 (
link)), a NOAA DEM (NOAA National Geophysical Data Center, 2009 ), and Dykstra and Dzwonkowski (2020b (
link)). For topography, Lidar was converged to a 10m DEM using Opentopography. For bathymetry, the NOAA DEM was used to analyze the bay geometry but had a limited spatial extent and missing data in the mid delta. Thus, landward of the bayhead, depth, and area of the Mobile and Tombigbee Rivers were calculated using a DEM of the longitudinal channel from Dykstra and Dzwonkowski (2020b (
link)). No comparable data of the Tensaw could be acquired. Channel width was measured every 2 km and included all five major anastomosing channels of the Tensaw distributary (i.e., Tensaw, Blakely, Apalachee, Raft, and Middle Rivers). Because the Middle River regional avulsion was half the length of the Tensaw, Middle River widths were measured at a 1 km interval. Sinuosity was calculated by dividing the centerline length by the length of a low‐passed centerline using a 10km‐moving mean, the bin size revealing the highest mean sinuosity.
Dykstra S.L., Dzwonkowski B, & Torres R. (2022). The Role of River Discharge and Geometric Structure on Diurnal Tidal Dynamics, Alabama, USA. Journal of Geophysical Research. Oceans, 127(3), e2021JC018007.
