2.1
Wind and storm impacts on circulation, sediment transport and salinity changes: Atchafalaya-Vermilion Bay, Louisiana, USA
Nan D. Walker, Coastal Studies Institute, Louisiana State University, Baton Rouge, LA; and S. Dartez, X. P. Zhang, G. W. Stone, A. Babin, A. S. Haag, S. Myint, and J. V. Letter
The Atchafalaya-Vermilion Bay system is comprised of five inter-connected shallow coastal bays that are impacted by seasonally varying river inputs and wind forcing. The Atchafalaya River discharges approximately 30% of the Mississippi River flow and 40-50% of the Mississippi River’s sediment load into this coastal bay system with a peak discharge usually in spring. Coastal observing stations were instrumented in autumn 1997 to obtain continuous measurements of conductivity, temperature, optical back-scatter, water level, current speed and direction and meteorological data. In 1999, the program was expanded to include two more stations and real-time data acquisition capabilities (see http://www.esl.lsu.edu/research/baywatch/baywatch.html). Satellite measurements from SeaWiFS and NOAA AVHRR are used in quasi-real time to provide a spatial view of the river discharge plume and its regional influence as well as quantitative spatial and temporal data on temperature, suspended sediments, and chlorophyll a. Terra MODIS is providing exciting new capabilities for detecting and tracking water masses with distinct color signatures.
The measurements have demonstrated extreme variations in salinity, surface suspended sediments and temperature that are directly attributable to fluctuations in wind forcing and river discharge on time scales ranging from tidal, to synoptic and seasonal. Wind and storm impacts are paramount, maximizing water level set-up/set-down, sediment transport and salinity fluxes. Impacts of recent hurricanes and tropical storms are demonstrated. A statistical model is presented that hind-casts salinity fluctuations for the western bay region. incorporating key environmental inputs including discharge from three rivers, wind stress, water level, rainfall, and tidal regime. The results are being used to validate numerical modeling efforts and to aid in the development of management policies for the biologically productive and controversial lower Atchafalaya Bay system.
Session 2, Ocean Processes
Thursday, 8 November 2001, 1:00 PM-3:15 PM
Next paper