Forecasting Hurricane Storm Surge on the River

David Reed Bob Stucky Lower Mississippi River Forecast Center Today’s Talk

• The Problem – Surges from Hurricanes • Sea, Lake, and Overland Surge Heights (SLOSH Model) • Dynamic Wave Operational Model (DWOPER) • Merging These Together

Hurricane Betsy – September 11, 1965 (Mississippi to Forecast River Surges River - ) Hurricane Storm Surge The Problem

• Hurricanes can cause the Mississippi River to rise rapidly due to Storm Surge

• Ships can be grounded or swamped due to these rapid rises

Hurricane Betsy – September 11, 1965 (Mississippi River – Louisiana) Hurricane Storm Surge – The Problem

• Flood gates and loading docks must be closed which takes time to complete

Hurricane Betsy – September 11, 1965 SLOSH Model

• Sea, Lake, and Overland Surge Heights (SLOSH Model) • Forecasted storm surge from hurricanes based on Forward Speed Intensity Track Size SLOSH Model – Cont’d

• SLOSH can be run for 35 grids/basins along the Gulf or Atlantic Coasts • Each basin grid is a continuously changing polar grid • basin used in our Lake Ponchartrain Basin analysis (outlined in white) SLOSH Model – Cont’d

• Higher resolution inland • Contains topography and levees which is periodically updated

SLOSH Model

• Model is run about 24 hours prior to landfall based on TPC forecast

• Output provided to NWS offices in a binary file

• SLOSH Display program allows for animation of output from SLOSH

• Local software determines hydrograph at West Pointe a la Hache where continuous levees begin along the Mississippi River DWOPER

• NWS Dynamic Wave Operational Model (DWOPER) • One-dimensional unsteady state flow model • LMRFC has DWOPER setup to run on the Lower Ohio/Mississippi Rivers to the LMRFC DWOPER Schematic Lower Ohio/Mississippi

Chester, IL RM 160.9 km above Junction Smithland Lock & Dam, IL RM 99.8 km Upper Mississippi Cumberland R Ohio RiverTennessee Barkley Dam, KY Ohio/Mississippi Junction R RM 1535.0 km RM 40.7 km Kentucky Dam, KY RM 40.5 km Memphis, TN RM 1181.9 km AHP

Middle Mississippi Legend RM = river mile AHP = above Head of Passes BHP = below Head of Passes

Vicksburg, MS RM 701.2 km AHP

Lower Mississippi River Mississippi Storm Surge

Head of Passes (RM 0.0km) Gulf of Mexico RM -37.0 km BHP DWOPER SCHEMATIC Storm Surge Segment

Upstream Boundary Red River Landing, LA Flow (m3/s) RM 486.7 km AHP

Baton Rouge, LA RM 367.6 km AHP

Donaldsonville, LA RM 282.3 km AHP Legend RM = river mile AHP = above Head of Passes

Reserve, LA

RM 223.2 km AHP M i s s i s s i p p i R i v R i e i p r p M i i s s i s s

New Orleans, LA RM 165.4 km AHP

Downstream Boundary West Pointe a la Hache, LA Stage (m) RM 78.4 km AHP DWOPER – Cont’d

• For storm surge, run • Upstream boundary model from Red River Stream flow at Red Landing, LA, to West River Landing Pointe a la Hache, LA • Downstream boundary • West Pointe a la Forecasted storm Hache – start of surge hydrograph continuous levees (stage) at West Pointe along both sides of the a la Hache Mississippi River Lower Mississippi River Dynamic Wave Operational (DWOPER) Model Red River Landing to West Pointe a la Hache RM 302.4 to RM 48.7 Merging SLOSH Output with DWOPER • Within 24 hours of landfall, SLOSH model runs produce a forecasted surge hydrograph (stage) at West Pointe a la Hache

• LMRFC uses the SLOSH forecasted surge at West Pointe a la Hache as the DWOPER downstream boundary condition

• DWOPER models the surge wave as it propagates upstream

• Flood wave fully contained within levee system with no lateral inflows or outflows Merging SLOSH Output with DWOPER • LMRFC issues stage forecasts with crests on the Mississippi River at and below Red River Landing

• NWS field offices may issue river warnings or include other river information in Hurricane Local Statements

Hurricane Georges 1998 Location 24 hours prior to landfall

• forecast 24 hours prior to landfall

• SLOSH runs provide forecasted stage heights at West Pointe observed track - black boxes forecasted track- white boxes ala Hache Surge September 1998

Mississippi River at West Pointe a la Hache, LA

4.0 West Pointe a la Hache 3.5 Observed 3.0 SLOSH computed surge Simulated 2.5

2.0

1.5 Stage (m) NGVD (m) Stage 1.0

0.5

0.0 9/26/98 9/27/98 9/27/98 9/28/98 9/28/98 9/29/98 9/29/98 9/30/98 12:00 0:00 12:00 0:00 12:00 0:00 12:00 0:00 Date/Time (GMT) Hurricane Georges Surge September 1998

Mississippi River at , LA

4.0 New Orleans 3.5 Observed 3.0 Simulated 2.5

2.0

1.5 Stage (m) NGVD (m) Stage 1.0

0.5

0.0 9/26/98 9/27/98 9/27/98 9/28/98 9/28/98 9/29/98 9/29/98 9/30/98 12:00 0:00 12:00 0:00 12:00 0:00 12:00 0:00 Date/Time (GMT) Hurricane Georges Surge September 1998

Mississippi River at Baton Rouge, LA

5.0 Baton Rouge Observed 4.5 Simulated 4.0

3.5

3.0

2.5 Stage (m) NGVD (m) Stage 2.0

1.5

1.0 9/26/98 9/27/98 9/27/98 9/28/98 9/28/98 9/29/98 9/29/98 9/30/98 12:00 0:00 12:00 0:00 12:00 0:00 12:00 0:00 Date/Time (GMT) Real-time River Forecasts Hurricane Georges’ Surge

RIVER FORECAST…LOWER OHIO/MISSISSIPPI RIVER LOWER MISSISSIPPI RIVER FORECAST CENTER NATIONAL WEATHER SERVICE SLIDELL LA 1020AM CDT SUN SEP 27 1998

STATION FS 7AM 24HR ……F O R E C A S T…… STG CHG 0928 0929 0930 1001 1002 CREST/DATE/TIME MISSISSIPPI RIVER …OBSERVED... RED RIVER LANDING 48 20.4 +1.1 21.9 21.4 20.9 20.9 20.7 22.5 9/28 7 PM CDT 21.80 9/28 2PM CDT BATON ROUGE 35 7.5 MSG 12.3 9.4 8.9 8.5 8.4 13.0 9/28 9AM CDT 12.19 9/28 5AM CDT DONALDSONVILLE 27 5.5 +0.9 12.0 7.1 6.8 6.4 6.4 12.0 9/28 7AM CDT MSG RESERVE 22 4.8 +0.9 11.0 6.0 5.8 5.7 5.7 11.2 9/28 6AM CDT 10.35 9/28 1AM CDT NEW ORLEANS 17 4.5 +1.1 10.2 5.8 5.6 5.5 5.5 10.8 9/28 4AM CDT 10.16 9/27 10PM CDT

FS = FLOOD STAGE IN FEET NGVD STG = STAGE IN FEET NGVD MSG = MISSING

NOTE: All NWS river forecasts are issued to the public in English units Summary - Conclusions • Ability to merge the SLOSH model output with land-based dynamic river models

• Produces excellent river surge forecasts when SLOSH predicted surge hydrographs are reasonable

• Hurricane induced river surges propagate rapidly upstream

• Provides valuable river surge information for shipping/barge industry and for flood gate management

• Concept should be applied to smaller coastal rivers and streams