1. Regional flooding frequency analysis
Vermillion River/bayou teche

2. Agenda Welcome and Introductions – Harold Schoeffler
Presentation “A Regional Flooding Frequency Analysis” – Dave Dixon
Contributing Speakers
Mark R. Wingate, P.E. Deputy District Engineer for Programs and Project Management for the U.S. Army Corps of Engineers New Orleans District
Nick Sims, Project Manager with the U.S. Army Corps of Engineers
Don Segrera, manager of the Teche Vermilion District
David Cheramie, manager of the Bayou Vermilion District
Guy Cormier, St. Martin Parish President
Bill Fontenot, St. Landry Parish President
J. Paul Kemp LSU Hydrologist
Monique Boulet, Chief Executive Officer, Acadiana Planning Commission

3. topics Video Overview of Regional Watershed
Understanding what happened during the August 2016 flood
Analysis of the August 2016 flood
Regional recommendations for prevention of future flood events

4. Data sources and Observations
Noaa
U.S. Geological Survey
Army Corps of Engineers
Observations and Field Trips

5. Vermillion river Historical Flood events
’ Higher! #*
’ lower $
’ lower $

6. Historical Remediation/navigation and Water Quality projects
1957
Dredging of Vermilion
Construction of drainage control for Bayou Courtablu to Basin
Other Projects and Notes
1982
Commissioned Teche-Vermilion Freshwater Project
Late 90s
NOAA lowered the flood stage for Vermilion (12’ $ 10’)

7. Vermilion River >12 ft Flood Frequency Measured and Forecast 1970-2040

8. Vermilion River >10 ft Flood Frequency Measured and Forecast 2000-2040

9. Annual Rainfall & Vermilion River Annual Flood Events 1999-2017

10. Annual Rainfall & Vermilion River Annual Flood Events 1999-2017(2016 Normalized)

11. Other Areas Red River Bayou Cocodrie Bayou Des Cannes Mermantau River
79.34 Miles
Other Areas
Red River
Bayou Cocodrie
Bayou Des Cannes
Mermantau River
Bayou Cocodrie
57.5 Miles
Bayou Des Cannes
34.5 Miles
33.75 Miles
Mermantau River

12. Flood event data Since 1970 Red River at Alexandria $ (79 miles north)
Bayou Cocodrie at Clearwater $ (58 Miles north)
Bayou Des Cannes near Eunice $# (35 miles northwest)
Mermantau River as Mermantau$# (34 miles west)
Vermilion River at Lafayette # (steady increases since 1970)

13. u.S. geological survey 1988
USGS conducted and published a hydrologic features and processes of the Vermilion river study

15. 2016 Flood data

16. 2016 Flood data

17. 2016 Flood data vermilion flood stage bench marks
12 days river was > major flood stage
21 days river was > moderate flood stage
28 days river was > old 12’ flood stage
55 days for river to return to pre-flood stage

18. Vermilion River data (after August 15 crest)
Vermilion river average falls per day
-0.16’ / day for 12 days.
-.25’ / day for the next 44 days
Weather data after the crest
Until Oct. 8, rain totaled 6.61 inches(slightly less than normal)
August 15 until Oct 8, 37 days with N-NE-NW winds and 18 days with S-SE-SW winds(Predominately favorable 66% of time)
No Abnormally High Tides

19. 2016 bayou teche data
Keystone dam south of st. Martinsville stage bench marks
Days stage in feet
2 >16
7 >14
14 >12
19 >11
40 to return to pre-flood stage

20. 2016 Flood- Vermilion River vs. Bayou Teche key comparisons and Totals
Stages
12 days river was at > 16ft stage
2 days bayou was at > 16ft stage
55 days for river to return to pre-flood stage
40 days for bayou to return to pre-flood stage
Volumes -Water from North of Lafayette into the River or Teche
Approximately 274,253 acre/feet of water flowed south at Surrey
Approximately 212,2285 acre/feet of water flowed south at Keystone
Total of 486,538 acre/feet of water
486,538 acre/feet of water = 760 square miles!
Volumes do NOT INCLUDE water entering the river south of Surrey

21. Summary and conclusions
Greater than 12 ft flood frequencies on Vermilion river INCREASED BY A FACTOR OF 5x SINCE 1970!
Local parish coulee maintenance is NOT THE ONLY PROBLEM
The Vermilion river is DRAINING VERY SLOWLY
The Vermilion river WATERSHED HAS CHANGED

22. Possible causations
Shoaling in the river bottom-last dredging was in 1950’s
Flood water flows and backflows into Cypress Island Swamp
Inadequate flood gate drainage capacity at Bayou Cortableau- West Atchafalaya Spillway levee
Inadequate channel capacity of Bayou Teche (Keystone Dam)

23. Other potential issues
Teche-Vermilion Freshwater Project - Unintended Consequences
Red River Navigation Project
Increase in development in Lafayette metro area
Bridges on river designed in the 50’s causing a dam effect
Too many drains into the river

24. remedies & recommendations
Add additional flood gates to the Bayou Courtableu –West Atchafalaya Spillway Levee
Provide an alternative drain for the Cypress Island Swamp
Add flood control gates in the Keystone dam
Dredge the river in conjunction with the parishes coulee cleaning and retention pond efforts
Visual Overview of Recommendations

25. Benefits of executing the recommendations
Future Flood Prevention
Better water quality in the basin, Cypress Island Swamp, and Lake Fausse Pointe
Possibly Lower Flood Insurance Rates
Improved community credit rating for bond issues - Some rating entities have threatened to downgrade ratings if communities do not address flooding risks

26. Takeaways fROm this Meeting and What you can do
This Problem CAN BE FIXED!
express your concern regarding the lack of action to resolve the regional problems
Your U.S. rep(Clay Higgins)
Your local parish presidents, mayors, police jurors, and council members
There should be a sense of urgency to fix the problem before we have another major flood event

27. Thank You for your time and consideration of this issue
Without your help
WE ARE AT RISK
Questions and Public Comments