Patterns in Time of Extreme Tides and Sea Level Rise over The 21 st Century: Puget Sound and the Other Marine Waters of Washington State Harold O. Mofjeld JISAO Senior Fellow and UW/Oceanography Affiliate Professor

Focus of the Talk: Marine Waters of Washington State 21st Century Tides and Sea Level Rise Providing the Best Available Science Marine Waters of Washington State 21st Century Tides and Sea Level Rise Providing the Best Available Science

Reporting Results of a Pilot Study to: Provide initial scientific results and insights Identify next steps to improve the science and make it available to those who need it Provide initial scientific results and insights Identify next steps to improve the science and make it available to those who need it

Complementary to Ongoing Work by the Climate Impacts Group, e.g.: Mote et al. (2008) on sea level rise in Washington’s marine waters Petersen (2007) Masters thesis on providing useful information to governments and agencies in the region Doug Canning’s work on sea level rise and fieldwork on high waters Mote et al. (2008) on sea level rise in Washington’s marine waters Petersen (2007) Masters thesis on providing useful information to governments and agencies in the region Doug Canning’s work on sea level rise and fieldwork on high waters

Some Stakeholders: Counties, cities, and towns Local, state and federal planning and regulatory agencies Property owners and investors Interest groups Public Counties, cities, and towns Local, state and federal planning and regulatory agencies Property owners and investors Interest groups Public

Approach: Compute tidal predictions at long- term tide stations Add Mote et al. (2008) sea level rise scenarios Look for patterns in the occurrences of extreme (high and low) water level events Compute tidal predictions at long- term tide stations Add Mote et al. (2008) sea level rise scenarios Look for patterns in the occurrences of extreme (high and low) water level events

REF.: TIDAL DATUMS AND THEIR APPLICATIONS NOAA Spec. Publ. NOS CO-OPS 1, 2000

Dividing WA Marine Waters into Four Regions: Puget Sound Eastern Straits Northwest Olympic Peninsula Outer & Southern Coast, Including Large Embayments Puget Sound Eastern Straits Northwest Olympic Peninsula Outer & Southern Coast, Including Large Embayments

Reference Tide Stations:

Examples of Coastal Types in the Four Tidal Regions WA Dept. of Ecology Shoreline Aerial Photos

Seattle, Central Puget Sound Highly Developed Shoreline

Silverdale, Dyes Inlet Commercial and Private Development

Tahuya River Mouth, So. Hood Canal Private Shoreline Development, Habitat

Near Padilla Bay NER Reserve, Eastern Straits Shoreside Agricultural, Natural Habitat

Ocean Shores, Open Coast Developed, but with Dune Buffer

Cape Shoalwater, Open Coast Developed, but Possible Erosion

Observed Sea Level Trends at Reference Tide Gauges -- The Recent Past --

Elliott Bay, Seattle

Observed Mean Monthly Sea Level (MMSL) at Seattle

Friday Harbor -- San Juan Islands

Observed Friday Harbor MMSL

Neah Bay -- Olympic Peninsula

Example of a Tide Gauge -- Neah Bay

Observed MMSL at Neah Bay

Toke Point -- Outer Coast

Observed MMSL at Toke Point

Assumed Sea Level Rise Profiles for the 21st Century Based on Mote et al. (2008) Scenarios Relative to Mean Sea Level in 2000 Mote et al. (2008) values given for 2050 and 2100 Smooth curve (quadratic) fit through these values Allows for increasing upward trends toward the end of the 21st Century Relative to Mean Sea Level in 2000 Mote et al. (2008) values given for 2050 and 2100 Smooth curve (quadratic) fit through these values Allows for increasing upward trends toward the end of the 21st Century

Reference Tide Stations:

PUGET SOUND

NW PENINSULA

CENTRAL & SOUTHERN COAST

Predicted Tides For The 21st Century Looking for patterns in the high and low tides in their 18.6-yr cycle Noting that the tides vary significantly with location in the WA marine waters Sea level rise to be added later Looking for patterns in the high and low tides in their 18.6-yr cycle Noting that the tides vary significantly with location in the WA marine waters Sea level rise to be added later

Olympia -- Southern Puget Sound

Predicted Tides on May 12-13, Straits of JdF and Puget Sound

FOCUSING ON SEATTLE EXTREME PREDICTED TIDES: LOOKING AT HEIGHTS AND TIMING REFERENCE LEVEL FIXED AT MLLW FOR THE TIDAL EPOCH

Seattle Tides (May-June 2008)

SEATTLE TIDE STATION: SAMPLE OF EXTREME PREDICTED TIDES

SEATTLE EXTREME PREDICTED TIDES

Nodal Variations of Tidal Amplitudes

SEATTLE HIGHEST PREDICTED TIDES

SEATTLE: HIGHEST PREDICTED TIDES

SEATTLE: TIMES OF HIGHEST PREDICTED TIDES

SUMMERWINTERSUMMERWINTER (UTC) (PDT)(PST) EARLIEST2:3214:215:32 PM6:21 AM AVERAGE3:4415:276:44 PM7:27 AM LATEST5:0416:368:04 PM8:36 AM RANGE (hr):

SEATTLE LOWEST PREDICTED TIDES

SEATTLE: LOWEST PREDICTED TIDES

SEATTLE: TIMES OF LOWEST PREDICTED TIDES

SUMMERWINTERSUMMERWINTER (UTC) (PDT)(PST) EARLIEST18:196:259:19 AM10:25 PM AVERAGE19:037:0210:03 AM11:02 PM LATEST19:487:4110:48 AM11:41 PM RANGE (hr):

SEATTLE TIDAL DATUMS (Without Sea Level Rise)

Adding Sea Level Rise To The Extreme Predicted Tides At Seattle

PUGET SOUND

SEATTLE HIGHEST PREDICTED TIDES

SEATTLE LOWEST PREDICTED TIDES

Extreme Predicted Tides at Seattle: 21st Century with Very High Sea Level Rise (SLR per Mote et al., 2008, for Puget Sound)

LOOKING AT THE OTHER TIDAL REGIONS Eastern Straits (Friday Harbor) NW Olympic Peninsula (Neah Bay) Central & Southern Coast (Toke Point) Eastern Straits (Friday Harbor) NW Olympic Peninsula (Neah Bay) Central & Southern Coast (Toke Point)

Reference Tide Stations:

FRIDAY HARBOR EXTREME TIDES

PUGET SOUND

NEAH BAY EXTREME TIDES

NW PENINSULA

TOKE POINT EXTREME TIDES

CENTRAL & SOUTHERN COAST

Pilot Study for Washington’s Marine Waters: Summary of Results The extreme predicted high tides show very little variation during 18.6-yr nodal cycles, except in the Eastern Straits Hence, they tend to track sea level rise closely Note that ENSO and other interannual variations will be important for potential coastal flooding The extreme predicted high tides show very little variation during 18.6-yr nodal cycles, except in the Eastern Straits Hence, they tend to track sea level rise closely Note that ENSO and other interannual variations will be important for potential coastal flooding

Pilot Study for Washington’s Marine Waters: Summary of Results The extreme predicted low tides show more variation during 18.6-yr nodal cycles, with some regional differences There will be periods in the next decades when nodal variations in the tides can mimic apparent sea level rise effects on low tides that may occur much later in the 21st Century The extreme predicted low tides show more variation during 18.6-yr nodal cycles, with some regional differences There will be periods in the next decades when nodal variations in the tides can mimic apparent sea level rise effects on low tides that may occur much later in the 21st Century

Pilot Study for Washington’s Marine Waters: Summary of Results The months of the year and the times of day when extreme tides occur change very little throughout the 21st Century Note that the reference levels (datums) for water levels will be adjusted periodically during the Century in response to sea level rise The months of the year and the times of day when extreme tides occur change very little throughout the 21st Century Note that the reference levels (datums) for water levels will be adjusted periodically during the Century in response to sea level rise

Predicting Water Level Patterns in Washington’s Marine Waters: SOME NEXT STEPS Use tidal models to extend the coverage of predicted tides from just the reference tide stations to any location in the marine waters Update regional sea level rise predictions as these become available, since these are evolving rapidly Include ENSO and other interannual variations, at least statistically, to better represent actual water levels Use tidal models to extend the coverage of predicted tides from just the reference tide stations to any location in the marine waters Update regional sea level rise predictions as these become available, since these are evolving rapidly Include ENSO and other interannual variations, at least statistically, to better represent actual water levels

Predicting Water Level Patterns in Washington’s Marine Waters: Some Next Steps Develop a set of tidal GIS products that can be used for planning purposes, augmenting CIG and WA Dept. of Ecology programs Publish results in appropriate forms (e.g., websites, reports, articles, …) Encourage scientific community to take advantage of upcoming tidal variations in field and modeling studies on marine effects of climate change Develop a set of tidal GIS products that can be used for planning purposes, augmenting CIG and WA Dept. of Ecology programs Publish results in appropriate forms (e.g., websites, reports, articles, …) Encourage scientific community to take advantage of upcoming tidal variations in field and modeling studies on marine effects of climate change

Patterns in Time of Extreme Tides and Sea Level Rise over The 21 st Century: Puget Sound and the Other Marine Waters of Washington State Harold O. Mofjeld JISAO Senior Fellow and UW/Oceanography Affiliate Professor