Saturday, February 13, 2010

Unplanned Beach Retreat - The Coastal Act and seawalls

The CCC annd authorized Local Coastal Plans should not permit seawall construction on an eroding coastline when it would threaten recreational access to the beach protected by Coastal Act Sections on Public Access 30210-30214 and Recreation, Sections 30220-30222 .

  • Seawalls should not be approved on eroding coastlines unless it is clear that there is a viable mitigation plan.
  • Seawalls fix the the back boundary of the beach. So long as the shoreline is experiencing a net retreat, a net sea level rise, or natural seacliff retreat, the width of the beach will decrease with the construction of a protective structure.
  • Without mitigation that can be performed we have a de facto Unplanned Beach Retreat Policy - our beaches will shrink between wall and water.
  • The Coastal Act provides several guiding and potentially conflicting principles on how to deal with this complex issue making regulation difficult. We want to address this conflict.
  • 30007.5 states that when "...conflicts be resolved in a manner which on balance is the most protective of significant coastal resources."
  • 30235 requires approval of seawalls " protect existing structures or public beaches in danger from erosion and when designed to eliminate or mitigate adverse impacts on local shoreline sand supply.
  • Section 30604(c) requires that every coastal development permit (including for seawalls) issued for any development between the nearest public road and the sea include a specific finding that the development is in conformity with the public access and public recreation policies of [Coastal Act] Chapter 3.
  • Coastal Act Sections 30210 through 30213, as well as Sections 30220 and 30221 specifically protect public access and recreation.
  • Section 30210: references Section 4 of Article X of the California Constitution
  • Section 30211: requires that "Development shall not interfere with the public's right of access to the sea..."
  • Section 30212(a): Public access from the nearest public roadway to the shoreline and along the coast shall be provided in new development projects�
  • Section 30213: Lower cost visitor and recreational facilities shall be protected, encouraged, and, where feasible, provided. Developments providing public recreational opportunities are preferred.
  • Section 30220: Coastal areas suited for water-oriented recreational activities that cannot readily be provided at inland water areas shall be protected for such uses.
  • Section 30221: Oceanfront land suitable for recreational use shall be protected for recreational use and development unless present and foreseeable future demand for public or commercial recreational activities that could be accommodated on the property is already adequately provided for in the area.
  • The cumulative effects of seawalls on shoreline access along with the present approval policy and rate of seawall construction and approval makes the governing policies of maintaining access along the coast impossible to enforce
  • We must use the Coastal Act policies to balance in favor of the environment per Section 30007.5, and per Section 4 of Article X of the California Constitution that "...give the most liberal construction to this provision, so that access to the navigable waters of this State shall be always attainable for the people thereof."

Monday, February 1, 2010

The importance of coastal bluffs in supplying San Diego area beaches with sand

Figure 10. Estimated percentage of beach-sediment contributions to the Oceanside Littoral Cell for the study area between April 1998 and April 2004 (a statistically dry period). (from Adam P. Young, Scott A. Ashford (2006) Application of Airborne LIDAR for Seacliff Volumetric Change and Beach-Sediment Budget Contributions. Journal of Coastal Research: Vol. 22, No. 2, pp. 307-318.)

I've been thinking a bunch about this topic over the past few weeks as a long string of larger than normal surf have coincided with some very high tides. Easily every beach I've seen in the past two weeks has shown signs of erosion. Also see Andrea's posts below which do a great job of documenting the problems in Oceanside. The addition of the heavy rains have complicated things even more, and where they are not restrained by seawalls, beach cliff erosion is very active. If you've been down the paved trail to Black's Beach, you can see this pretty clearly.

In 2005, UCSD grad student Adam Young and his advisor Scott Ashford published "Application of Airborne LIDAR for Seacliff Volumetric Change and Beach-Sediment Budget Contributions" in Journal of Coastal Research. The important result from this work is summed up in the figure above. Classical thinking had been that rivers provided up to 90% of beach sand in the Oceanside littoral cell. Young and Ashford's work found that seacliff (or bluff) erosion contributed 67% to beach sediment in the Oceanside cell.

The reception of this work was varied. Many who fight against seawalls, saw this as a concrete (pun intended) example of the detrimental effects of seawalls, which are blocking sediment into our littoral cells. Obviously, the seawall advocates were not so pleased and many were quick to dismiss the work.
"We think it's pure hogwash," countered Paul Santina, president of the Beach and Bluff Conservancy. (from Study: Bluffs contribute most of the sand on local beaches, By: Paul Sisson North County Times, Oct 16, 2005)
Most of the scientific criticism about Young and Ashford's study was based on the short period of time that their analysis included. They looked at a six year period of time, which also was during a dry period. Six years in the geological sense is short, but their methods are accepted as valid by many in the coastal research community.

To help put this academic research into a real life example, head down to Black's Beach or any of the beaches in front of non-armored bluffs. You're likely to see patches of large amount of sediment eroding off the bluffs (bluff failures), which will soon make it's way into our littoral cell.

Here are some additional links regarding Adam Young's work: