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Synthesis and Local Perspectives from a Coastal Geologist David L. Revell University of California, Santa Cruz

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Presentation on theme: "Synthesis and Local Perspectives from a Coastal Geologist David L. Revell University of California, Santa Cruz"— Presentation transcript:

1 Synthesis and Local Perspectives from a Coastal Geologist David L. Revell University of California, Santa Cruz

2 Sea Level Changes

3 Tectonics Data from Vincent (1989) and Komar (1997) Figure Paul Komar 1998

4 Coastal Processes

5 West Coast Different Definitions of Shoreline Different Definitions of Shoreline Purposes Purposes –Research –Property Boundaries –Marine Boundaries –Jurisdiction –Access From Journal of Coastal Research - July 2005 Shoreline Definition and Detection – Boak & Turner

6 Oregon Marine Boundaries

7 West Coast Property Boundaries Washington – “Ordinary High Water Mark” Washington – “Ordinary High Water Mark” –Should be obvious otherwise if unidentifiable then MHHW Oregon – “MHW but land seaward of the Oregon Coordinate Line aka Statutory Vegetation Line aka Beach Zone Line has a public dedicated access” Oregon – “MHW but land seaward of the Oregon Coordinate Line aka Statutory Vegetation Line aka Beach Zone Line has a public dedicated access” –Separates Public from Private Beaches –16 ft. contour surveyed in 1967 NGVD29 (1947 correction) California – “Ordinary High Tide Line” California – “Ordinary High Tide Line” –Interpreted as the average of neap tides or the intersection of MHW and the shoreline

8 Where is my property line? 1938

9 Who owns accretions? Washington - state owns all accretions except when land ownership existed prior to statehood. Washington - state owns all accretions except when land ownership existed prior to statehood. Oregon – All lands between MHW and Statutory Vegetation Line or the seaward most line of vegetation whichever is farther inland belong to the state of Oregon. Actually a separate parcel not taxable. Oregon – All lands between MHW and Statutory Vegetation Line or the seaward most line of vegetation whichever is farther inland belong to the state of Oregon. Actually a separate parcel not taxable. California – Property owner owns accretions except when accretion is caused by human alterations to the shoreline, then accretion belongs to the state. California – Property owner owns accretions except when accretion is caused by human alterations to the shoreline, then accretion belongs to the state. BUT – if accretion is caused by a jetty constructed by the United States then all accreted land belongs to the federal government and NOT the state as long as the land adjacent to the water is navigable – Submerged Lands Act. BUT – if accretion is caused by a jetty constructed by the United States then all accreted land belongs to the federal government and NOT the state as long as the land adjacent to the water is navigable – Submerged Lands Act.

10 Examples of Accreted Lands in Oregon

11

12 Research Question If there is no indication of a reduction of sand supply in the Dredge Records, yet we know that there have been reductions in sediment supply. Then where is the sand coming from? Could the beaches be eroding and supplying the sand to account for the reduction in supply, in which case we would expect to see a decrease in the beach widths across the cell? Methods –photogrammetry, remote sensing, and field mapping. Combine Air Photo based shorelines with datum based shorelines Make water level adjustments to photo based shorelines Photos by Art Sylvester

13 Evaluating Long-Term Beach Changes to the Santa Barbara Sandshed 40% reduction in sediment supply from damming of the four major rivers

14 Research


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