1

Toward Modeling of River-Estuary-Ocean Interactions to Enhance Operational River

Forecasting in the NOAA National Weather Service

Hassan MashriquiSeann Reed

Cecile Aschwanden

Office of Hydrologic Development (OHD)National Weather Service (NWS)

4 March, 2009

2

Acknowledgement

• Jon Janowicz

Federal Emergency Management Agency (FEMA), Region 3

• Kevin Hlywiak

Middle Atlantic River Forecast Center (MARFC), NWS

33

122 Weather Forecast Offices (Outlined in Black)

CurrentCurrentNOAA/NWS Hydrologic Service DeliveryNOAA/NWS Hydrologic Service Delivery

13 River Forecast Centers (Colored)

4

Current Forecast HydrographsCurrent Forecast Hydrographs

5

Coastal Areas Outside the Forecast ZonesLMRFC

SERFCMARFC

6

Freshwater

River-Estuary-Ocean (REO) Interactions

Estuary

Ocean

Often we use numerical models to simulate these complex coastal environments

7

Model Types

• 1D models – HEC-RAS/FLDWAV, SOBEK, MIKE 11

• 2D models – ADCIRC, MIKE 21, SELFE

• 3D models – CBOFS2, SELFE, DELFT3D, MIKE 3D

8

Project Goals

Provide an accurate hydraulics model that extends from the river-estuary confluence to existing forecast points and beyond if necessary to achieve accuracy.

Provide accurate river flow forecasts to NOS operational estuary models

9

MARFC

Daily Forecast Boundary

Estuary

Ocean

Interactions

River

River

River

Tide & Wind

River-Estuary-Ocean (REO) Interactions Modeling

Freshwater

10

Approach

Evaluate 2D/3D models and a combination of HEC-RAS and 2D/3D models Evaluate ADCIRC, SELFE/ELCIRC, Mike Flood FM in the Chesapeake Bay Region Use operational models, e.g. the NWS SLOSH and NOS CBOFS2, to establish downstream boundary conditions for the evaluations Requirements for 2D Models Allow time series of freshwater inflows Continuously model both astronomical tides and storm tides or surges Allow for wetting and drying on the land surface

11

The Chesapeake Bay Operational Forecast System (CBOFS)

Operational forecast system by Center for Operational Oceanographic Products and Services (CO-OPS)/Coastal Survey Development Lab (CSDL) since August 2001

Nowcast and forecast Water Level

Nowcast and forecast WindForecast for the ports within

Baltimore Harbor and Hampton Roads.

12

Little Falls near Washington, DCMARFC’s Forecast Point

on the Potomac River

Daily Streamflow

020000400006000080000

100000120000140000160000

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

September, 2003

Disc

harg

e (ft

^3/s

)

Little Fall Bumps, DC

Point of Rocks, MD

Hancock, MDPaw Paw, WV

Inflow boundary for the CBOFS is 7 miles from

Little Falls forecast point

13

Model Geometry is Important

Error due to inaccurate boundary

14

The Potomac River 1D HEC-RAS

15

1936 Potomac River Flood

16

1D HEC-RAS allows bridges to be coded in the model to determine the backwater effects. Many 2D/3D models do not

have this capability

17

HEC-RAS simulated water level profiles for the Potomac River near Washington DC

Chain Bridge near DC

18

Potomac River HEC-RAS domain

19

Boundary Condition from CBOFS or SLOSH

HEC-RAS will simulate water level near DC

Hurricane Isabel, 2003

20

HEC-RAS test simulation without freshwater inflow or wind forcing. Boundary tide at Lewisetta, Va and simulated water level near Washington DC

September 2003

Sta

ge (f

t)

Predicted water level near Washington DC

Input water level near Lewisetta, Va

21

Summary

1D – Fast, ready to use, accounts for bridges

2D/3D – Better physics, complex

Application – depends on the customer need, project location etc.

22

Thank you