Tuesday, December 15, 2015

C-St Ventura - cobble and erosion Dec 2015

In February 2014, the City of Ventura constructed a cobble berm to protect the public amenities along the promenade and bike path in Ventura.  Surfrider documented this project, and noted the rapid migration of the imported river rocks along the shoreline.

On December 11, 2015, a large westerly swell flooded the Pierpont neighborhood and damaged the Ventura pier.

Ventura pier, Dec 11, 2015

  Not surprisingly, one of the palm tree planters along the promenade at C-St collapsed into the surf.

C-St palm tree planter collapsed from coastal erosion during swell event of Dec 11, 2015

Surfrider had contacted the City in October when it was evident that the planter was at risk.  Apparently others had expressed the same concern.

C-St palm tree planter at risk of erosion Oct 26, 2015

As a result of public concern for the palm trees, Ventura City Council approved "emergency funding" to renourish the cobble berm.  Unfortunately the funding approval came too late, and re-nourishment is not expected until after the new year.

Here's the cobble berm with sand "cap" shortly after it was constructed in 2014:

This is what it looked like on Dec 11, 2015:

C-St cobble berm - palm tree planter failure - Dec 11,  2015

Looking west from the Figueroa storm drain
C-St cobble berm Dec 2015
Looking East from Figueroa storm drain
C-st cobble berm Dec 2015

C-St cobble berm - promenade stairs - Dec 11,  2015

Promenade stairs - Dec 11,  2015

It is evident from our monitoring and these images that much of the cobble migrated down into the cove.  A significant berm formed during recent winter swells in front of the promenade stairs.  This berm provided protection for the stairs that have suffered damage in past winters.

So although the cobble nourishment did not protect the palm trees during this largest swell in recent history, it did provide a benefit to the promenade just downcoast.

The city has a Coastal Commission permit for ongoing nourishment along Surfers Point.  Although the one-time nourishment done in 2014 did not provide the anticipated level of protection, regular nourishment would progressively add volumes of cobble for more protection.

Although it is tempting to call for a more permanent revetment to protect the palm trees along the promenade, this would have other impacts.  Coastal structures exacerbate erosion downcoast.  They also disrupt coastal processes and recreational access to the beach.


Ensure Ongoing Funding:
Surfrider recommends that the City of Ventura establish a permanent budget for beach maintenance with oversight by a qualified coastal engineer.  Regular monitoring and renourishment is necessary to maintain a beach to protect the promenade in its current location.

Simplify Implementation:
We also recommend that the strict engineering specifications for constructing a cobble berm be waived in favor of a less expensive and more frequent nourishment.  It was clear during construction  that the waves quickly re-worked the carefully graded cobble berm, undoing thousands of dollars of work in a matter of hours.   A more efficient use of funds may be to simply dump smaller quantities of cobble in an easily accessible location and allow the ocean to work it into a berm.

Complete the Planned Managed Retreat:
It may also be beneficial to consider implementing Phase 2 of the Surfers Point Managed Shoreline Retreat project as envisioned.  The additional large quantity of sand and cobble would ultimately benefit the downcoast beach.  However, this would not eliminate the root cause of the problem.

Solve the Root Cause of Erosion:
The root cause of the erosion problem is infrastructure built too close to a shoreline that is receding due to rising sea levels and a sediment deficit. There's not much that can be done locally to combat rising seas, but it is noteworthy that record tides up to one foot above the predicted high tide have been recorded this year due to the warm water in the Pacific Ocean.

The current sediment deficit is the result of the long-term drought.  Indeed, the erosion which damaged the then-recently constructed bike path in 1991-1992 occurred during the last major drought.  This year's much-anticipated el nino floods, if equivalent to the big events in the past, will deliver a large quantity of sand and cobble to the river mouth. This sediment will naturally fill in along the point providing a benefit for many years.

Of course, the ultimate long-term solution is the restoration of the Ventura River through the removal of Matilija Dam.  This project is necessary for many reasons, but it was beach erosion that kicked off the first studies in 1998.  Much progress has been made on that project, but funding remains a major hurdle.

More info on this blog:

Ventura River Ecosystem: C-Street, Ventura - more cobble berms
The Managed Retreat Process at Surfers Point
Surfers Point Working Group considers phasing plan
Surfers Point Managed Shoreline Retreat
Matilija Dam

In the News:

The perfect storm - VCReporter
High tide, high surf cause debate, erosion on Ventura beaches
By Michael Sullivan 12/17/2015

Ventura beach disappointment 
VCReporter    Letters 12/31/2015
It is unfortunate that the city of Ventura has opted for a “hard solution” to coastal erosion at Surfers Point following the loss of a palm tree along the promenade. Indeed it’s ironic since the city was a strong proponent of the highly successful “managed shoreline retreat” project on the adjacent section of the point managed by the Fairgrounds. It’s also disappointing considering that they have a standing permit to renourish the beach with sand and cobble, but have been unable or unwilling to dedicate funding to maintain Ventura’s greatest asset. Indeed, intentional neglect is a useful strategy used to invoke the “emergency” loophole in the California Coastal Act.
Beachgoers will soon have to negotiate “a 265-linear-foot rock revetment, approximately 15 feet tall and 30 feet wide, consisting of approximately 1-3-ton stones.”  And it will not be long before the erosion caused by this new structure will necessitate even more rocks, forever changing Ventura’s famed “C Street” surf break.
Paul Jenkin
Surfrider Foundation, Ventura Chapter

UPDATE Jan 31,2016

Following much discussion, the City of Ventura has decided to exercise their right to the Emergency Permit issued by the California Coastal Commission.  
Surfrider expressed concerns that a rock revetment will exacerbate downcoast erosion, perhaps leading to additional armoring in the future as well impacting the recreational beach.  We also suggested that the event of December 11 was an extreme event, even in this round of El Nino storms and swells, and the loss of a palm tree did not constitute an immediate threat to the promenade.
The revetment will be considered "temporary" until a Coastal Development Permit is issued by the commission. The City has indicated they will reevaluate the situation following the winter season and seek funding to assess their alternatives.
Surfrider shall monitor the effects of this structure and retain the right to appeal the final permit.