SEA LEVEL CHANGE AND TRANSPORTATION PLANNING by Bob Dean University of Florida. Questions to Address.
University of Florida
(1) What is the Long-term History of Sea Level Change?(2) Is Global Sea Level Currently Rising? If so, What is the Rate?(3) Is Global Sea Level Accelerating? If so, What is the Rate?(4) Prognosis for Future Sea Level Rise Rates. (5) Relevance to ransportation System Design
(1) Incorporate Effect in Initial Design(2) Retrofit at Some Future Time
An Afterthought: Possible Role of Sunspots on Global Climate Change
Relative Sea Level Rise (RSLR) = Global Sea Level Rise + Local EffectsGlobal = EustaticLocal = Tectonic + Compaction + Post Glacial Rebound + Subsidence + …….
(1)Thermal expansion of water(2) Alpine glaciers(3) Ice Sheets: Greenland, and Antartica
a) Production Rates of Oil, Gas and Water
b) Reduction in Bottom Hole Pressure
Yes. Over the Past Century, the Rate Has Been Between 1 and 2 mm/year (I Like 1.2 mm/year).A Caveat: Most Tide Gages Are Located Near Areas of Ground Water Extraction. Effect on Gage Readings?
Rate of CO2 Increase, Mauna Loa, HI
Long-term Eustatic Rate
(1) There are Indications of Sea Level Acceleration Although They Are Weak and do not Appear to be Increasing(2) Probably Won’t Know About Anthropogenic Effects Definitively for 30 or More Years
Probably, However, the Timing and Rates are Extremely UncertainAs Support, the Predicted Rates of Acceleration Have Decreased Since 1984 When Some Early Predictions Started
* Some Highways: Increase Protection as Need Becomes Apparent* Bridges and Other Infrastructure Less Suited for Retrofitting: Allow for RSLR in Original Design
* Base design on predictions of local RSLR* Usually, not readily retrofitted during design life* Flooding of special concern if evacuation route* If evacuation route, design for upper limit of probabilities
* Several coastal engineering options for retrofitting during design life, including * Adding more and heavier armor units * Beach nourishment to reduce size of waves
Consider:and evaluate a and b from the data on the following slide. b is an acceleration term.
This leads to:
Is the average of the time period over
which is determined. Solving for
a and b from the data yields very unrealistic results signifying that the data are not well conditioned for this purpose.
NRC Report (1984)“The Prognosis for Sea Level Rise Should Not be a Cause for Alarm or Complacency”
(1) Definitions(2) Discuss Magnitudes of Relative Sea Level Rise(3) Is the rate of sea level rise increasing(4) Engineering responses to sea level rise (NRC Report)