|October 18, 2013: C-Street panorama before cobble berm|
|May 16, 2014: C-Street panorama with cobble berm|
In February 2014, the City of Ventura constructed a "cobble berm" to protect the public amenities along the promenade and bike path in Ventura. The panorama above illustrates the exposed riprap and concrete debris that, while providing some level of erosion protection, also presents a hazard to beachgoers and surfers. According to the City staff report:
|C-St before cobble nourishment - debris marked for removal|
|Feb 19, 2014: C-St cobble nourishment in progress|
Over the last several years, severe erosion has become visible along the state beach at Surfers' Point and the Promenade. The loss of sand and beach is threatening the palm trees, the bike path and other City public improvements along an 800-foot stretch of beach. To restore and protect this shoreline and to prevent further erosion from occurring, it is recommended that the successful shore protection that was installed with the Surfers' Point Managed Retreat Project (2010) be extended easterly. The complete nourishment of this stretch of beach requires the placement of an estimated 4,800 cubic years of small stone/cobble and 1,000 cubic yards of sand topping. In addition, existing concrete and other debris that is encountered by this work would be removed. The improvements would effectively widen the beach along the bike path in this area by 10-feet and would protect the bike path and other infrastructure from costly damage.
|March 26, 2014: C-St cobble berm|
approximately 10 years and perhaps longer. Periodic cobble beach nourishment is an economically viable option that is necessary for ongoing stability of the beach as well as
protection of existing public improvements.
At the regular City Council meeting on September 16, 2013, Council authorized the use of $450,000 of line of Credit Repayment Funds to be use to fund this beach nourishment work. Approximately 1/2 to 1/3 of this 800 foot shoreline will be addressed with available funding … The apparent low bidder… submitted a bid in the amount of $319,970…
These aerial photos help illustrate the evolution of the shoreline following the construction of the cobble berm.
|October 18, 2013: C-Street before cobble berm|
|February 25, 2014: C-Street shortly after construction of cobble berm|
The image above taken shortly following the construction clearly shows the downcoast extent of the constructed cobble berm and the concrete debris directly downcoast.
|May 16, 2014: C-Street 3 months after construction of cobble berm|
Although the site did not experience many large winter swells in 2014, the beach quickly adjusted to the new cobble berm. The image above clearly illustrates that by May much of the cobble had migrated downcoast, filling in on top of the concrete debris.
|May 16, 2014: C-Street view looking toward the cove further downcoast of project site|
The image above shows how the cobble has migrated around the Figueroa St drain and into the cove. The cobble is evident in the photo below looking back upcoast from the drain on March 26, 2014 - note the relatively homogenous rocks filling in between the larger riprap from the constructed berm in the far background of the image.
|March 26, 2014: View from Figueroa storm drain looking upcoast toward cobble berm. Cobbles are migrating through the riprap toward the viewer.|
|Aug 29, 2014: View from Figueroa storm drain looking upcoast toward C-St cobble berm. Note riprap now completely buried by cobble migrating downcoast|
We shall continue to monitor Ventura's cobble shoreline management, as there is a lot to learn. This cobble berm placed within the active littoral zone is a contrast to the Managed Shoreline Retreat project just up the point. Questions remain as to how long this cobble remains in place, how fast it moves along the shoreline, and how rising tides and future large swells will affect this stretch of coast. Stay tuned…