Flood Sediment March 2019

The 2019 flood of the Mississippi River was the longest in recorded history, lasting more than 235 days. The Bonnet Carré Spillway into Lake Pontchartrain is opened by the USACOE when the Mississippi River reaches a flow of 1.25 million cubic feet per second. For the first time in history, it was opened twice in one year and remained open for 44 days (Feb 19 – April 11, 2019) and 79 days (May 10 - July 27, 2019). Throughout the event, VIIRS and MODIS satellite imagery were processed to track flood waters and inorganic suspended sediment distribution using a newly developed VIIRS algorithm. The March 21, 2019, VIIRS image (above) demonstrates some of the highest regional concentrations of inorganic sediment along the Louisiana and Mississippi coastlines, as it followed the peak river flooding by only a few days. Maximum concentrations of 125-150 mg/l were measured in the Mississippi River plume as well as the sediment plume that filled Lake Pontchartrain, due to the opening of the Spillway. Preliminary results of this study entitled “Tracking Inorganic Sediments using the MODIS and VIIRS Satellite Sensors during the Record-breaking 2019 Mississippi River Flood Episode” were presented at the Gulf of Mexico Conference in Baton Rouge, LA, 25-29 April 2022. (Authors: Nan Walker, Alaric Haag and Vanessa van Heerden). The research was sponsored by the Gulf of Mexico Coastal Ocean Observing System and Louisiana Sea Grant.