rising relative to San Diego, and farther north, San Francisco is rising at an 

 even greater rate compared with Los Angeles. The sea-level trend of 

 -0.4 millimeter/year for the northwest Pacific coast is the result of an 

 emergent shoreline, and sea-level rates for the southwest coast for the same 

 period are 1.0 millimeter/year, which reflects a recessional coastline (Lyles, 

 Hickman, and Debaugh 1988). 



Gulf US Coast 



14. The gulf coast is experiencing a local, relative rise in sea-level 

 due to subsidence combined with eustatic components. Several studies of the 

 Louisiana coast indicate rates of subsidence of about 10 millimeters/year 

 (Nummedal 1983, and Ramsey and Moslow 1987). The sparsity of tide gages along 

 the Gulf of Mexico, however, has made it difficult to obtain accurate rates of 

 sea-level rise. Another problem with tide-gage information from this area is 

 that many of the gages are not located on stable substrate, which makes it 

 difficult to filter and correct the records. A complex set of interactive 

 factors that contribute to subsidence in the gulf region include: an active 

 sedimentary, deltaic basin; movement along growth faults; removal of ground 

 water, oil, and gas; saltwater intrusion, and dredging and channelization of 

 fluvial systems. Table 2 lists the rate of subsidence reported in the litera- 

 ture for the gulf region. 



Table 2 

 Rates of Subsidence Reported in the Gulf Region 



Location 



3 mm/year 

 9 mm/year 

 100 mm/year 



12 mm/year 



1.2 mm/year 



Galveston, Texas 

 Louisiana 

 Grand Isle 

 Louisiana 

 Southwestern 

 Louisiana - 

 Southwestern 

 Florida 



Reference 



Leatherman 1983 

 Nummedal 1983 

 Ramsey 1986 



Delaune et al. 



1983 



Scholl 1954 



