Evaluating the effects of water influx on the Mississippi sound: current vs. Historical relationships

This research investigated the influence of the opening of the Bonnet Carre Spillway and other fresh water inputs on the Mississippi Sound. The Bonnet Carre Spillway was completed in 1931 and was constructed to protect New Orleans whenever the Mississippi River is at flood stage. The spillway drains into Lake Pontchartrain a brackish-water lagoon north of New Orleans which then drains into Lake Borgne and subsequently into the Mississippi Sound. The inflow of water from the spillway changes the water chemistry of all receiving water bodies and impacts the waters of the Mississippi Gulf Coast. We collected in-situ temperature specific conductance and dissolved oxygen data for the Spring of 2018 opening event and used these data in addition to remotely sensed data for tracking the movement of river water plume/plumes through the coastal waters. Remote sensing data was collected from Landand Sentinel 2 platforms and were all processed to track freshwater plumes where possible. Specific conductance and temperature both displayed the effect of the Bonnet Carre Spillway within 13 and 18 days respectively while dissolved oxygen did not show a clear pattern of impact. The three remote sensing analyses completed were: Sentinel 2 single band and multispectral analysis Land8 multispectral analysis and Landthermal analysis. All of which were successful at identifying the Bonnet Carre Spillway plume near the source influx. Identification of the Bonnet Carre Spillway plume within the Mississippi sound was not possible due to water column mixing beyond the source influx. Lastly features present in our study area were the result of a combination of Pearl River plumes and increased sediment suspension from Lake Pontchartrain flushing out through the Rigolets channel