coastal flood forecasting at tamu-cc/tcoon

Coastal Flood Forecastingat TAMU-CC/TCOONDr. Patrick R. Michaudpmichaud@sci.tamucc.edu

January 30, 2003

Dr. Philippe Tissotptissot@cbi.tamucc.edu

Dr. Daniel Cox, Dr. Alex Sadovski, Scott Duff, Jessica Tishmack, Deidre Williams, Zack Bowles, Aimee Mostella, Jeremy Stearns, Kelly Torres, Alex Drikitis

Collaborators:

TCOON overview

Started 1988 Over 50 stations Primary Sponsors

General Land Office

Water Devel. Board US Corps of Eng Nat'l Ocean Service

Gulf ofMexico

TCOON overview

Measurements Precise Water Levels Wind Temperature Barometric Pressure

Follows NOAA/NOS standards

Real-time, online database

Typical TCOON station

Wind anemometer Radio Antenna Satellite Transmitter Solar Panels Data Collector Water Level Sensor Water Quality Sensor Current Meter

Other real-time observing systems

Real-time Navigation Port of Corpus Christi Port Freeport NOAA PORTS

Water-Quality Nueces Bay Salinity Oso Creek Dissolved

Oxygen Offshore Weather

Data management design principles

Preserve source data Annotate instead of modify

Automate as much as possible Maintain a standard interchange format Avoid complex or proprietary

components Emphasize long-term reliability over

short-term costs

Uses of observation data

Tidal Datums Littoral Boundaries Oil-Spill Response Navigation Storm Preparation/

Response Research

Water-level graph

Water-level prediction

…what will happen next?

Tide predictions

tide: The periodic rise and fall of a body of water resulting from gravitational interactions between Sun, Moon, and Earth.

Tide and Current Glossary, National Ocean Service, 2000

According to NOS, changes in water level from non-gravitational forces are not “tides”.

Harmonic analysis

Standard method for tide predictions Represented by constituent cosine

waves with known frequencies based on gravitational (periodic) forces

Elevation of water is modeled ash(t) = H0 + Hc fy,c cos(act + ey,c – kc)

h(t) = elevation of water at time tH0 = datum offsetac = frequency (speed) of constituent tfy,c ey,c = node factors/equilibrium args

Hc = amplitude of constituent ckc = phase offset for constituent c

Harmonic tide predictions

Obtain amplitudes and phases of harmonic constituents from trusted sources (e.g., NOS)

or Perform a least-squares

analysis on observations to determine amplitudes and phases of harmonic constituents

To predict tides using harmonic analysis:

Harmonic prediction

Apply the amplitudes/phases to get:

Prediction vs. observation

It’s nice when it works…

Prediction vs. observation

…but it often doesn’t work in Texas

Water level != tide

In Texas, meteorological factors have a significant effect on water elevations

Uses of harmonic predictions

However, harmonic predictions can still be useful! Consider…

…what will happen next?

Isidore begins to (re-)enter the Gulf…

Uses of harmonic predictions

If we add harmonic prediction…

…what will happen next?

Uses of harmonic prediction

Uses of harmonic prediction

Uses of harmonic prediction

landfall

Isidore & JFK Causeway

Effect of Isidore at JFK causeway

Harmonic WL prediction -present capabilities

Automated system for computing harmonic constituent values from observations database

Harmonic predictions available via query page for many TCOON stations

Harmonic WL prediction –(near) future capabilities

Persistent model forecast Apply difference between latest observation and

harmonic prediction to future predictions Forecasts page on DNR web site

Obtain forecasts from different models Harmonic predictions Persistent model Neural-network model Linear-regression/statistical model Hybrid models

Information about water-level forecasting methods Statistics on previous forecasts

Neural-network forecastsDr. Philippe Tissot