2019 Bonnet Carr Spillway Event USM Monitoring and Assessment Image - - PowerPoint PPT Presentation

The University of Southern Mississippi

School of Ocean Science and Engineering

2019 Bonnet Carré Spillway Event USM Monitoring and Assessment

Image: Sun Herald

Read Hendon, USM-GCRL

Bonnet Carré Spillway

• General purpose is to reduce Mississippi River level, control

flow rate, and minimize down-river flooding.

• Designed and constructed in response to Great Flood of 1927
• Construction completed in 1931; first opening in 1937

Source: http://www.mvn.usace.army.mil/Missions/Mississippi-River-Flood-Control/Bonnet-Carre-Spillway-Overview/Spillway-Operation-Information/

Bonnet Carré Spillway - 2019

• Most number of days open in single year (123 d)
• First time opened twice in the same year
• First time opened in consecutive years

25 50 75 100 125 1937 1945 1950 1973 1975 1979 1983 1997 2008 2011 2016 2018 2019 Number of Days Open Year of Opening

Days Open - 1st Opening Days Open - 2nd Opening

First 70 Years = 8 Openings Past 12 Years = 6 Openings

Data Source: http://www.mvn.usace.army.mil/Missions/Mississippi-River-Flood-Control/Bonnet-Carre-Spillway-Overview/Spillway-Operation-Information/

• 2019 Discharge = 1.35 trillion cubic feet (15,000,000+ Olympic pools)

Bonnet Carré Spillway - MDMR

• Marine Resources Monitoring and Assessment

Bonnet Carré Spillway - USM

• Expanded Monitoring and Assessment

 Water Quality  Remote Sensing and Modeling  Oyster Spat Settlement

Archive of weekly updates available on USM-GCRL website: http://gcrl.usm.edu/news/2019.bonnet.carre.spillway.overview.php

Bonnet Carré Spillway - USM

• Water Quality

 nutrients concentrations  chlorophyll-a  source water identification  suspended particulates  phytoplankton community  bacteriology

• Remote Sensing and Circulation Modeling – understand

dynamics and extent of the spillway discharge

• Biological Resources – oyster spat settlement

USM Field Sampling Outputs

Depiction of surface salinity levels in the Mississippi Sound for July 17 (top) and August 22 (bottom), as extrapolated from field data at expanded water quality stations (yellow squares).

Complete closure of spillway = July 27

BILOXI GULFPORT BAY ST. LOUS OCEAN SPRINGS PASCAGOULA BILOXI GULFPORT BAY ST. LOUS OCEAN SPRINGS PASCAGOULA

USM Field Sampling Outputs

Depiction of bottom salinity levels in the Mississippi Sound for July 17 (top) and August 22 (bottom), as extrapolated from field data at expanded water quality stations (yellow squares).

Complete closure of spillway = July 27

BILOXI GULFPORT BAY ST. LOUS OCEAN SPRINGS PASCAGOULA BILOXI GULFPORT BAY ST. LOUS OCEAN SPRINGS PASCAGOULA

Preliminary results from July 25 (left) and August 13-14 (right) sampling to determine sources of freshwater in the Mississippi Sound, based on isotopic signatures.

• Top panels depict the percentage of all water in the sample assigned to the Mississippi River.
• Bottom panels depict the percentage of freshwater in the sample assigned to the Mississippi River.

25 July 2019 13-14 August 2019

% MR in Total % MR in FW

USM Field Sampling Outputs

• Source Water Tracking

Complete closure of spillway = July 27

Warmer colors (yellow to red) represent higher salinity waters typically observed in the region, while cooler colors (blue) are representative of lower salinity waters.

USM Coastal-Ocean Modeling

Regional surface salinity model output for July 16 (left) and August 15 (below).

Complete closure of spillway = July 27

• Particulate backscattering from satellite ocean color data indicating suspended particulate

matter in the water column

• White areas indicate data gaps as a result of cloud cover

MAY 2018 MAY 2019

USM Discharge Monitoring

USM Sampling

• Oyster Spat Assessment

 Monitor and quantify recruitment of oyster larvae