2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...
2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...
2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...
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<strong>Bolsa</strong> <strong>Chica</strong> Lowlands Restoration <strong>Monitoring</strong><br />
<strong>2008</strong> <strong>Annual</strong> <strong>Report</strong><br />
several locations from the placement of the ebb bar offshore of the <strong>Bolsa</strong> <strong>Chica</strong> entrance. As a result,<br />
the statistical range of closure was re-computed for each historical transect and for the two new<br />
transects based on all available survey data collected between May 1963 and October 2007. The<br />
procedure used to calculate the statistical range of closure for each transect was identical to that<br />
employed for the CCSTWS-OC (USACE, 2002). The results are shown in Table 2-4.<br />
Statistical closure was assumed to occur at the point at which the standard deviation of all measured<br />
elevations ceased to decrease in value. The procedure used to compute the point of statistical closure<br />
at each profile is summarized below:<br />
Statistical closure was assumed to occur at the point at which the standard deviation of all measured<br />
elevations ceased to decrease in value. The procedure used to compute the point of statistical closure<br />
at each profile is summarized below:<br />
• Sea bottom elevations were interpolated at 15.2-m range intervals along all selected profiles.<br />
• The sample standard deviation of the interpolated elevations for all available survey profiles (σ)<br />
was calculated at each 15.2-m interval.<br />
• Statistical closure was assumed to occur at the point at which σ ceased to decrease.<br />
• The maximum depth of all available survey profiles at the point of statistical closure was<br />
recorded as the depth of statistical closure.<br />
• The distance from the transect origin to the point of statistical closure was recorded as the<br />
“range of statistical closure”. This range was adopted as the offshore boundary for the<br />
computation of shorezone volumes.<br />
Table 2-4. Statistical range and depth of closure at <strong>Bolsa</strong> <strong>Chica</strong> area transects.<br />
Transect Designation<br />
Range of Closure<br />
(m)<br />
Depth of Closure<br />
(m, NAVD88)<br />
249+30 473 -6.97<br />
311+22 900 -9.29<br />
318+30 793 -8.80<br />
333+30 717 -8.67<br />
350+71 519 -7.70<br />
378+29 381 -6.73<br />
423+89 549 -8.72<br />
The onshore boundary of the control volume for both the shorezone and subaerial volumes was placed<br />
at the landward edge of the beach sand.<br />
Beach Width Measurements<br />
The results of the beach width measurements obtained by Moffatt and Nichol at the seven <strong>Bolsa</strong> <strong>Chica</strong><br />
area transects are presented graphically in Appendix 2-E. The plots include the MSL beach width and<br />
the horizontal distance from the back beach to the berm.<br />
The Corps beach widths, which consist of measurements from a consistent back beach position to the<br />
break-in-slope at the beach berm, are presented graphically in Appendix 2-F.<br />
Merkel & Associates, Inc. 122