Simulation of Salinity. In order to analyze the horizontal salinity variability during the simulation period, a series of data, sampled at 5-day intervals was extracted (Figures 2-13a through 2-13c). All data periods selected were near the slack before flood in order to remain consistent relative to tidal phase. On day 5, since the stage at the moment of the snapshot was near the beginning of flood for the mouth of Barataria Pass, maximum plume excursion from the mouth of the passes was observed. Inside the bay, lower salinities extended to the mouth of the basin. It can be seen easily that the high salinities are coming from the open boundary. It is notable that there are large gradients in the coastal waters due to the time and space variations of salinity imposed along the open boundary. On day 10, the situation is similar to that of day 5 except for the higher salinity values coming from the open boundary. By day 25, very high values of salinity are coming from the open boundary and penetrating far into the basin. There are big salinity gradients in the northeast region of the Gulf of Mexico in the model domain. On day 30, after several days of high salinity values at the open boundary, the high gradients increase at the coast. In shallow, bar-built estuaries, it is often assumed that the flow field is vertically homogeneous (Xxxxxxx, 1996). When the estuary is shallow, the velocity shear on the bottom may be large enough to mix the water column completely and make the estuary vertically homogeneous (Xxxx, 1973). The concern over the use of a two-dimensional model for this modeling study is in its application to deep channels, waterways, or passes, such as the Barataria Pass. As mentioned earlier, the Barataria Basin has five passes that connect to the Gulf of Mexico. Except for Barataria Pass, all of the other passes are very shallow. Barataria Pass, however, is wide (about 1 km) and deep (deeper than 12 m in the middle of the pass) perhaps allowing some stratification to be present, i. e., salt wedge might exist along the bottom during flood tide. This phenomenon can not be accounted for in the model. Figure 2-14 shows observed and simulated salinity at eight stations. It is apparent that at all the stations simulated salinity can capture low-frequency salinity variability but higher-frequency signal is missed. This is due to the fact that the salinity initial condition was based on salinity observations at the eight stations, and it completely missed any smaller horizontal...
