Compaction, water-level, and lithologic data were collected at extensometer sites on Bacon and Bethel Islands, anchored at 436 and 536 feet below land surface, respectively. The data reported here are part of a study of the processes causing subsidence in the Sacramento?San Joaquin Delta. The depths were selected to ensure that they were well below the peat layer and the primary aquifer, which minimized the effects of peat loss and shallow ground-water withdrawal. Compaction and depth to ground water were measured monthly at Bacon Island from September 1987 through August 1993 and at Bethel Island from August 1988 through August 1993. After automatic digital data loggers were installed at Bacon Island in December 1988 and at Bethel Island in September 1989, hourly readings also were made. Calculated rates of compaction were 0.0015 and 0.0016 feet per year at Bacon and Bethel Islands, respectively. Cumulative compaction at the Bacon Island site from September 1987 to August 1993 was about 0.009 feet. Cumulative compaction at the Bethel Island site from August 1988 to August 1993 was about 0.008 feet.
Additional publication details
USGS Numbered Series
Extensometer, water-level, and lithologic data from Bacon and Bethel Islands in Sacramento-San Joaquin Delta, California, September 1987 to August 1993
U.S. Dept. of the Interior, U.S. Geological Survey ;
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