2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

Bolsa Chica Lowlands Restoration Monitoring
2008 Annual Report
y 3 /year) for the second year after the inlet was to be connected to the ocean, for a total of
approximately 230,000 m 3 (300,000 y 3 ) over the first two years. The predicted flood shoal location is
illustrated in Figure 2-1. Investigations were completed to assess the true rate of shoal accretion and
distribution pattern of flood shoal development.
Full Tidal
Basin (Phase I)
Modeled Shoal Area
Tidal Inlet
Scale 1’’= 1,800’
Figure 2-1. Predicted flood shoal area (cited from M&N 1999)
Methodology
The rate and distribution of sand accretion in the FTB inlet has been assessed during the first two
monitoring years on January 19, 2007, June 27, 2007, January 10, 2008, and July 1, 2008. After the
January 2007 survey it became clear that a larger area needed to be surveyed to capture the extent of
the shoaling, therefore all following surveys extended a considerable distance further to the north. A
survey was also conducted on December 23, 2008 by the maintenance dredging contractor hired to
remove the accumulated sand from the inlet during the 2008/2009 winter season. This survey was
performed by the dredging contractor’s surveyor, CLE Engineering, Inc., and was intended to
document the pre-dredge bathymetric condition.
The surveys were conducted from a small survey vessel with sub-meter accurate differential global
positioning system (dGPS) and a survey-grade SyQuest Hydrobox ® fathometer. Land surveying was
conducted using a total station to complete areas that were too shallow to conduct hydrographic
surveys during the various survey intervals. The bathymetric survey area was previously presented in
Figure 1-1. The methodology for the CLE survey in December 2008 was comparable to that
completed by M&A, as described above. The December 2008 survey area did not cover the western
Merkel & Associates, Inc. 100