A Look at the Delta through the years and the latest attempt to mess with Nature or Revise the Delta!

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1820-1859

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Delta maps:  Elevations, Subsidence and Seismic

     Update 11/21/2011:  DWR continues to plan target areas of the Delta for "restoration" based on elevations, so that must be an important factor in the planning process.  The problem is different agencies and mapping services show different elevations for the same lands.  The 2007 LIDAR survey can be off by 3+ feet due to plants and other surface variations...perhaps that is the reason for the conflit of information?           For seismic history and risk in the Delta, go to "Delta Earthquake History" page added August 2012

Issues/elevations/compare_elevations.pdf

General comment:  Over the years, some of the Delta islands have subsided due to the soil types found on those islands, and the farming methods.  However, a majority of islands are within 10 feet of sea level, and have good levees to protect them.  (Consider Holland that uses 100 foot levees to hold out the ocean!)  The levees of the Delta have NEVER failed from an earthquake, to anyone's knowledge.  But since the elevations have become a big issue, this page provides links to maps showing elevations over time.  Please note that islands like Sherman Island, which has subsided substantially, is owned by state agencies who were farming the island to lower it at one point.  Other islands, like Webb Tract and Bacon Island, have also been planned to be "in-Delta" water storage islands, so one would assume the owners of those islands were trying to get the islands as deep as possible.  The fact is, once farmers realized some of their practices caused subsidence, they stopped farming that way, and many islands no longer subside.  Anyway, here are various maps you can use to compare for your self.  Note that some large map sets (from 1906 and 1978-1980) will be scanned and added to this page area to provide good historical records.  Copyright note:  These maps are provided for educational purposes and not for sale or other commercial use.  If anyone claiming a copyright on any map below needs to request that a particular map be removed, please email us.






Delta area elevations according to BDCP



Subsidence of Delta Islands according to DWR

Earthquake effects on the delta according to modeling

San Francisco Bay and Delta earthquake projection planning
The above map shows how the WHOLE Bay Area is at risk for
earthquakes, and the most extreme risk is from Oakland to San Jose,
as shown by the purple color.

 

CALFED Seismic Vulnerability of the Sacramento San Joaquin Delta levees

m

Thickness or Organic Materials or Peat in the Delta

Subsidence of Delta Islands according to DWR

San Francisco Bay and Delta areas subject to Sea level Rise

 

 

 

Earquake modeling and planning for the Delta

The links below lead viewer to large data files, so the viewer can see details of specific areas of the Delta.  Note that the data from maps after 2005 do not match with data from earlier studies.  Soil types, elevations and island locations do NOT change the way some post-2005 maps show!
delta_elevations.pdf
 ***Elevation-Inundation-Subsidence_InteractiveMap.pdf
delta_elevations_map-large.pdf
elevations_2008_dwr-usr.pdf
bathy_overview.pdf
delta_elevations2007.pdf
***elevation_maps_compared.pdf
Elevation-2.pdf
***Elevation2001.pdf
2008elevations.pdf
Elevations_subsidence_seismic-mount_twiss_delta.pdf
Elevation-posteddpc2010.pdf
Elevation-posteddpc2010.pdf
Elevation-ucb.pdf
Fig_3.8_Overlap_of_SAV.pdf
Soil_Types_2009.pdf
Bathymetry_Elevation_West_Delta2009.pdf
southern_yolo_bypass_area_topography_lidar_2005.pdf
subsidence_to_2050.pdf
subsidence_to_2050-ucb.pdf
soil.pdf
usace_berkeley_grant_request2006.pdf
100_yr_flood.pdf
2001Elevation_map.pdf
2008_carbon_s_sites.pdf
2008yolobypass-map.pdf
R_207JLMap2_4.pdf
NorthDelta-ryer_liquification_status.pdf
bdcp_geology.pdf
current_si_relief.pdf

Earthquake shake potential for the San Francisco Bay and Delta

delta_elevations_large_map.cdr
delta_islands_subsidence.cdr
elevation.cdr
elevation_maps_compared.cdr



Delta soils map from 1935

delta organic soils

 

BDCP North Delta Elevations from BDCP 2010

Delta and Suisun Marsh soils tests

DFG Elevations or near-term acquisitions and enhancement priorities

Earquake modeling and planning for the Delta

 

   
 
 Index Summary 
Compiled by Delta citizens and Delta Voices Last Modified :01/15/14 04:34 PM Copyright 2009-2013 ,