By Dave Schwab Staff Writer
By Dave Schwab
La Jolla and much of the rest of the San Diego coastline does - but not as much as in years past.
This year's stormy winter was the culprit, depleting sand stockpiles on beaches up and down the coast.
Is there a significant sand deficit in the Jewel right now? "Absolutely, without a doubt," San Diego Lifeguard Lt. Nick Lerma noted. "And not just in La Jolla, it's in Mission Beach - all the beach areas."
But not to worry, added Lerma - it's just part of the natural cycle of sand removal/replenishment that takes places seasonally.
"Strong winter-type swells, often very close in frequency, are violent in nature, and they come up onto the beach and hit boardwalk and sea walls, and the net result is the sand is sort of mixed in with surge and it's moved offshore," he said. "Conversely, in the summertime, there's more of a gentle wave action that tends to replenish sand on beaches that have lost it."
Sand depletion can cause added difficulties for lifeguards. Citing one example, Lerma noted rocks normally covered by sand that are now exposed can create channels that contribute to rip currents.
Less sand on beaches also means people are crowded into less space, which "can create some negative social dynamics at the beach," he added.
But, with sand depletion a reality this summer, La Jollans have caught a break with unseasonably cool temperatures and cloudy skies.
"It's a blessing in disguise," Lerma said. "With very few sunny days, there have been less people coming to the beach. If we'd had the really hot days like we had last year, that would have exacerbated the whole issue of competition for space."
Rob Rundle, a principal regional planner for SANDAG, a regional planning agency, said they have had a regional monitoring program for years that measures the changes in beach width over time, documents the benefits of sand replenishment projects, and helps to improve the design and effectiveness of beach fills.
"We've measured beach width and sand depth at 44 different specific locations since 1996 along the coast from Oceanside to Imperial Beach," he said. "It gives us a good indication of what happens along the entire coastline looking at seasonal fluctuations, as well as year-after-year changes."
Rundle acknowledged that there's an endless cycle of give-and-take along the coast, with winter storms pulling sand off beaches and gentler summer swells pushing it back on.
"We definitely saw significant loss of sand this year," Rundle said.
To address the chronic problem of shoreline erosion in the San Diego region, SANDAG, as it did in 2001 and is preparing to do again, launched a Regional Beach Sand Project (RBSP). According to SANDAG's website, that effort dredged 2.1 million cubic yards of clean, beach-quality sand from offshore and placed it on 12 eroded beaches from Imperial Beach to Oceanside, including Torrey Pines State Beach. The second project is scheduled for construction in spring 2012.
Rundle said sand replenishment to offset deficits caused by winter storms is essential to preserving the coastal environment.
"We've definitely seen more bluff collapses when there's no sand, because sand protects the shoreline," he said. "So when there's no sand, the waves are going to hit closer to the bluffs. That poses a danger to public infrastructure, private property and to beach users below."
Sand deposition patterns that used to replenish coastal beaches have also changed.
"Historically, most of the sand for our beaches came from inland sources," Rundle said. "But inland sources have been cut off by sand and gravel extraction.
Everywhere the land is paved over with parking lots and subdivisions. Now almost all the sand we get is from bluff erosion."
Consequently, there's an absolute need for sand replenishment to maintain nature's balance, he said. "If we want to have sandy beaches, it requires management of the resource, placing sand on the beach, and figuring out a way to maintain it."