Part 2 Report: Coastal erosion in La Jolla leads experts to consider replenishment
The shoreline is in a constant state of change and we humans do as much as we can to keep up with it. We build seawalls, nourish our beaches with more sand and constantly create barriers to physically minimize the effects of that natural process. But it never stops — and it never will.
In the first part of this report, the La Jolla Light provided several scientists’ analyses of coastal erosion and beach nourishment along our coasts. In this second chapter, we researched answers to the question: Is replenishment worth it? We looked into some of the factors in the equation, like seawalls and sea level rise. Here is what we found out:
Seawalls are both part of the problem and the solution at the same time. These structures are built where the sea directly impacts the landform of the coast and their chief purpose is to protect property, infrastructure and human habitation.
Scattered all over our coast, they appear in different forms. The boardwalk in Mission Beach and the Children’s Pool walkway are seawalls. Robert Rundle, principal regional planner and sand expert at San Diego Association of Governments (SANDAG) explained that these structures are very controversial.
“Some of them appear to be natural because they’ve made them look like natural rock and aesthetically, they look better,” Rundle said. “Others are just big concrete walls.”
When people started constructing property and infrastructure too close to the shoreline, and the eroding effect of the ocean jeopardized those investments, it made sense for some to attempt protection with seawalls. Bird Rock, Solana Beach, Encinitas and other cliffside coastal communities offer examples of this practice.
Building a seawall not only modifies the natural state of the shore, but it prevents the constructed stretch from erosion and that will add sand to our beaches. In fact, when a community gets approval from the Coastal Commission to build a seawall, it needs to contribute to two mitigation funds: one is a recreational impact fee and the other a fund for future beach nourishment programs.
“There’s a good reason for seawalls, people want to protect their property, but that has a consequence,” Rundle said. “The contribution to the sand budget has been reduced.”
Attorney Marco Gonzalez is a long-time coastal activist. He believes that people who built on an eroding coastline took a risk and taxpayers shouldn’t have to pay for projects to protect them. “We shouldn’t be subsidizing them,” Gonzalez said. “That being said, the California Coastal Act and coastal laws require the State to approve seawalls to protect private property.”
Rundle added, “There are a lot of people who want to see the shore stay as natural as possible.”
Sea level rise
The scientific community and worldwide leaders took a unprecedented stand during the 2015 United Nations Climate Change Conference in Paris: They want to fight predicted sea level rise. The United Nations website for climate change (www.cop21.gouv.fr/) predicts that the average sea level rise is expected to be 9-12 inches by 2065 and 16-24 inches by 2100.
NOAA has developed online tools to calculate what a rise in sea level would mean in our local context. Using those tools, the La Jolla Light offers three maps to illustrate the effects on La Jolla Shores and Torrey Pines Beach.
The maps show that even a minimum 1-foot increase would result in serious flooding in the Torrey Pines area. A 2-foot rise would inundate part of the existing beach in La Jolla Shores, as well as compromise the Spindrift Golf Course. A third maps show the intense devastation that 6-foot flooding could cause in the area. These maps can be accessed at coast.noaa.gov/slr
Linwood Pendleton, an environmental economist who holds the International Chair of Excellence at the European Institute for Marine Studies, has published papers like “Estimating the potential impacts of climate change on Southern California beaches.” He currently lives in France, so he answered La Jolla Light’s questions via e-mail. “The effect of sea level rise on beaches is complicated,” Pendleton wrote. “More than just increased inundation, sea level rise can change the nature of waves (direction, angle, etc), and the degree to which beaches naturally accrete or erode, even when sediments are readily available.”
Torrey Pines, a case study
The paper “The economic costs of sea-level rise to California beach communities,” (Philip G. King, Ph.D., Aaron R. McGregor and Justin D. Whittet, California Department of Boating and Waterways San Francisco State University) modeled sea level rise scenarios in the next 100 years in five California beaches, one of them Torrey Pines.
The analysis considers the economic benefits of sandy beaches in terms of the funds they generate from residents and tourists, and the tax revenues garnered. In the costs category, it considers the monetary investments that beach nourishment and coast armoring require.
The study takes estimates of 3.2, 4.5 and 6.5 feet of sea level rise in the next 100 years and delves into the consequences of each. The scarce development at sea-level in the Torrey Pines Beach area would prevent much of the infrastructure flooding damage, that would be basically Highway 101 and the railroad, which would cost taxpayers $3.4 million in 2050 and $5 million in 2100. The scientists calculate that building seawalls to protect the infrastructure (at a computed cost of $68.5 million), the concurrent loss of a quarter of the existing beach by 2050 could result in a more than $45 million loss in habitat value, beach-goers spending and tax revenues.
The study states that using nourishment projects to maintain the existing beach width would require $6 million. “While nourishment could help to minimize losses related to recreational value, spending and taxes, nourishment could also result in reductions to habitat value not modeled in this report. Any future analysis should seriously evaluate incremental planning approaches, like managed retreat that promotes both the wellbeing of the natural coast and the long-term sustainability of coastal economies,” the study concludes.
Managed retreat is a concept many scientists are talking about, but one that many near-shore property owners may not like. It consists of allowing an area that was previously not exposed to flooding by the sea to become flooded by removing coastal protection.
Gonzalez called himself a “big fan” of managed retreat.
The costs of beach nourishment
Beach nourishment is not only expensive, it also takes a toll on the natural environment where sand is placed.
A research paper by UC San Diego biologists Tyler Wooldridge, Heather J. Henter and Joshua R. Kohn states that the recovery time for invertebrate populations living in the sand after a beach nourishment is longer than previously thought. The team monitored the invertebrate community for 15 months following the 2012 SANDAG replenishing program.
Those invertebrates are the food that sustains many shorebirds, and are a key agent of marine life ecosystems.
“It’s thought that white, sandy beaches contribute to the tourist industry, and that’s a very big component of our economy,” Kohn said recently, in an interview with KPBS. “Those forces need to be weighed against potential biological harm.”
Surf communities also don’t like beach nourishment. Julia Chunn-Heer, policy manager at the San Diego Surf Rider Foundation called these programs “a necessary evil at this point.” The surfers group has monitored the effect in the wave brakes of the 2012 SANDAG sand placement. Their conclusion is that smaller amounts of sand may disturb less the surf spots along the San Diego coast.
Chunn-Heer highlighted the economic and cultural importance of surfing. “How many people would sit at the beach if there were no surfers?” she asked.
So, is it worth it?
Environmental economist Pendleton suggested that there is no simple answer to whether beach nourishment is good or bad.
“Whether or not beach nourishment makes sense economically depends upon the cost and effectiveness of the nourishment, the potential benefits to people, the potential costs to ecosystems and the benefits they provide, and the alternatives (which include managed retreat, sea walls, etc) including all of the costs and benefits of the alternatives,” he wrote.
Pendleton suggested that a growing population and a possible future scarcity of sandy beaches should be computed as factors in the economic analysis of the beach nourishment benefits. He wrote, “We have to look at the annual costs and benefits of beach nourishment, as well as the long term costs and benefits to understand whether beach nourishment makes sense for San Diego and where.”
When asked the question, Is beach nourishment worth it? Gonzalez replied, “Absolutely. We loose the beach, we loose the recreational opportunity, we have a negative impact in terms of property, values, tourism and quality of life.”
He added, “In the extent that we value those things, I think we have the option of building seawalls, removing property or putting sand on the beach. Sand on the beach is our best option.”
On the topic, SANDAG planner Rundle said, “Someone needs to answer the question, Is it important it is to have a white sandy beach at Torrey Pines? And if that’s the case, chances are you are going to have to do artificial replenishment to keep it that way.”
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