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November 12, 2008
31539 views | 89 comments
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After hearing about the final demise of Pratte's reef
I felt a strong obligation to get the facts straight regarding Pratte's Reef and reefs in general. While I was a graduate student in coastal engineering at the University of Southern California (USC) I ran Surfrider's monitoring program for Pratte's Reef. For two years after Pratte's was installed, I checked the site almost daily, did monthly beach profiles, organized dive inspections and carried out offshore surveys.
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El Segundo, and all of the South Bay for that matter, is an ideal location to build a surfing reef. The area gets a lot of clean, long-period swell; the beaches are under-utilized (especially between El Segundo and Marina Del Rey) and the waves are mostly closed-out beachbreaks. Pratte's Reef however, was too small and too close to shore to take advantage of these factors and was doomed for failure before it entered the water. Pratte's was too small because the budget for the project was tiny -- initially only $300,000. To 'design' the reef, the engineer simply calculated the amount of sand that could be purchased for that amount of money with enough left over to pay for the bags and rent the barge. That led to a reef that was only about 900 cubic meters in total volume. Now what is 900 cubic meters? About 2.5 feet of the nearly 2.5-mile Long Beach breakwater. In other words, it is tiny. When the reef was installed in September 2000, the beach was in its 'summer profile' -- the beach is very wide with a steep berm. When the first swells of that winter hit, the beach was carved away, the sand was moved offshore and completely buried the reef. Through that first winter, NO ONE surfed Pratte's Reef and NO ONE ever saw it break, because it was completely buried in sand. In April 2001 a second set of bags was installed, bringing the total volume to almost 1600 cubic meters (or four feet of the Long Beach breakwater). These bags were placed directly on top of first set of bags. The reef was then about two feet deep at low tides (we would go out and stand on it) and eight feet deep at high tide. Between April 2001 and the early part of winter 2001/2002 was the only time anyone ever surfed the reef or actually saw a wave breaking directly on the reef. Through that first winter, NO ONE surfed Pratte's Reef and NO ONE ever saw it break, because it was completely buried in sand.
What happened next was that the reef disintegrated. The particular type of bags used for Pratte's Reef were small and cheap and could not handle the strain of waves breaking directly on top of them. The force of the waves either moved the bags or shredded them, letting the sand inside spill out. As the winter of 2001/2002 moved in, the 'reef' was beaten down to the natural sand level and was basically gone by the spring of 2002. When the remnants of the reef were finally removed this year, it was mostly covered in sand. Small portions of the reef bags may have been exposed by as much as 1 ft above the normal sea bed level, i.e. hardly a 'reef' any more. *** Now that you know the facts about Pratte's Reef, lets look at some of the other reefs in the water today: The Mount Reef in New Zealand is approximately 6,000 cubic meters in volume, which at four times the volume of Pratte's, is actually pretty small (about 17.5 feet of the Long Beach Breakwater). The 'bags' used on the Mount Reef are not really bags, but are better described as 'mega' sand filled containers (SFC's). The material is much more durable than the stuff used at Prattes' and each SFC is about as big around as a school bus and 2 to three times as long. In contrast the Pratte's Reef bags measured a tiny 4 ft x 7 ft x 10 ft (see the diagram). Two or three of the Mount Reef's 24 bags could make up the entire volume of Pratte's Reef. The Mount Reef is about 200 yards offshore and is very shallow at low tide. The reef is not sinking. The Mount Reef is working as a surf-break. People surf every time the swell is right -- I have surfed it myself. The reef breaks as a shallow, suck out slab and the truth is the body boarders dominate the spot. There is video on YouTube and photos of the Mount Reef with people surfing, body boarding, getting barreled and having a good time. At 60,000 cubic meters, the Gold Coast Reef (or Narrowneck Reef) is massive by comparison (yet still only 175 feet of Long Beach breakwater). The reef sits approximately 200 to 450 meters offshore. The mega-SFC's used at Narrowneck are similar to the bags used at the Mount Reef. The Narrowneck Reef is a true 'multi-purpose' reef in that it was designed to be a coastal protection structure first and a surfing reef second. It has succeeded on both fronts. The beach nourishment placed on that section of the beach in 1999 has been stabilized by the presence of the reef. During clean swells, the reef produces good surfing conditions and is utilized by the local crew. In 2000, the Narrowneck reef project won the prestigious Queensland State Environmental Award for a coastal project. Cables Reef in West Australia is approximately 3,300 cubic meters in total volume. Its construction was a bit different as it was made of rock units dropped into place. Cables breaks and people use it, however, its location does not have a great swell window, nevertheless, monitoring by the Centre for Water Research at the University of Western Australia suggests that the reef produces surfable waves 142 days/year, which is double the number of surfable days at that site before the reef went in. Our designs have already created good surfing waves and protected beaches from erosion. The simple fact is that reef type projects have never been given a fair chance in terms of budgets or expectations relative to 'traditional' coastal engineering projects. Stop for a second and note the size comparisons between the various reefs and just 1 of the many massive coastal projects that exists globally. It is boggling! The promise of multi-purpose reefs lies in their use as a form of coastal protection. It is a well-known fact that if you put something offshore that causes waves to break and lose energy, the shoreline will respond by becoming wider. This is known as a 'salient'. A classic example is the Santa Monica Breakwater. First built in 1933, it quickly formed a huge salient (see image). Eventually the beach at Santa Monica was filled out (through beach nourishment projects) to the width of that salient (see the other image). In other words, the entire beach at Santa Monica from Will Rogers to Venice is artificial and owes its existence to that breakwater. Of course, we are not advocating the rampant construction of meaningless breakwaters, but if there is a need for an offshore structure, why not build it with an eye for surfing? The truth is that a reef could be built every six months for the next 20 years and we still won't be close to getting back the amount of surfing resources that have been lost, damaged or negatively impacted by coastal development over the past half-century. With apologies to John Lennon, all we are saying is give reefs a chance. *Dr. Borrero earned a Ph.D. in Coastal Engineering in 2002 from the University of Southern California. He is currently a research scientist with ASR Limited in Raglan New Zealand and an associate of the Tsunami Research Center at the University of Southern California. He is a member of the Surfrider Foundation and believes in most of what Surfrider does. EXTERNAL LINKS: Download Link to Quarterly Monitoring Reports Download Link to Pratte's Reef Summary Paper Jose Borrero and Chad Nelsen Link to ASR website library page on multipurpose reefs SURFLINE HOME PAGE MORE SURF NEWS |
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Comments: (89) Add Your Comment
Howard Lorney, Mount Maunganui 11/19/2008 07:51 PM
I took the photo of the surfer at the Mount Reef. One of the only waves ridden in an hour of shooting. The poor guy took the drop, got a very brief barrel before getting sucked up turned over and dumped on the reef. I have a sequence of photos showing how short ride was for any one wanting them. Point is waves like this seldom occur and when they do there are better waves anywhere on the coast. Reef has failed as SURF REEF but sometimes can form nice shaped wave as demonstrated. Nice photo tho'
James 11/19/2008 12:51 PM
Facts, I am going to take a wild guess and say that the $250K that ASR so generously contributed to the Mount Reef is not included in the $1.5 million cost that Jose referred to is it?
gary 11/17/2008 05:13 PM
Jose: I always wondered why they placed prattes reef so close to the S**t pipe. Did that contribute to it's demise?
Facts 11/17/2008 12:49 PM
ASR has been monitoring the numbers surfing the reef since May 2008. Sometimes when there is swell it is the only place being ridden, sometimes the beach along side is packed with the reef empty, it varies greatly depending on swell and tide. People do ride it. Reef designers, ASR, have CONTRIBUTED NZD$250K to the reef including remedial work after the local construction team was removed from the project after delays and ineptitude.
Facts 11/17/2008 12:48 PM
A longer reef in deeper water would be optimal and produce a different wave, but the volume of such a reef would cost a great deal more. Was it oversold? Just saying the words “artificial reef” conjures up allsorts of expectations most which would require budgets in the tens of millions.
Facts 11/17/2008 12:47 PM
The Mt Reef is a short ( 50 m long, generally less than one wavelength) shallow reef, inside the surf zone when the waves are around 2.5 meters high. The wave breaks very hard and fast on the right and surges on the left (which needs widening and may be in the future). Because it is so small it is greatly affected by the tide. It represents the most bang for the money spent.
Mount Maunganui ,local,New Zealand. 11/16/2008 11:08 PM
To anyone that thinks we are spreading mis-information about the mount reef by saying its a failure,Have a look at www.surfcamsbop.co.nz ,theres some marker buoys that mark the reef.See if you can see anyone surfing the reef.
If your local community/council/beach is seriously considering a ASR similar to the Mount reef,then come to New Zealand,australia and see for yourselves what the Mount and narrowneck reefs are like.Bottom line is kerry blacks company did nothing to improve the surf.
mount local 11/16/2008 02:24 PM
i live in mt maunganui NZ, these photos are totally misleading, that reef is the biggest myth waste of money ever, it broke averagely for the first 3 months after installation and now is never surfable. ASR should be held accountable!
james see 11/16/2008 12:27 PM * PREMIUM MEMBER - Real Name
Build the Reefs!! Pump The Sand!!Who cares about the Price Tag. L.A.Harbor dept. built Pier 400 in less than 3 years.BIG$$$ Pier400 is the world's largest container dock. 400 acres= almost 2million sq ft of ocean.Someday surfer's in Cali.will figure it out.Good Luck I'am buying my ticket to get some waves.Save the Breakwall=Build Islands,Build Mega reefs(Tow in Spots/tsunami protection),Plant Kelp forest, Channel Ocean Currents(clean L.B.)build waves like Lower's,Pipe on the L.A./L.B. Breakwall
James 11/15/2008 05:58 PM
Your comparison is so misleading. You compare total costs and not cost per unit volume. You compared an erosion control structure (SM Breakwater) to an ASR that was never intended for erosion control. I would think you would at least use an "illustrative comparison" with the Narrowneck reef. What was the final price tag on the Narrowneck reef??
Cliff dweller 11/15/2008 05:32 PM
You guys ever see the barges coming over from Catalina full off rocks that they unload outside of San Clemente. Instead of dropping those bad boys way outside in deep water lets drop the rocks around seal rock and west reef, that way well have two slab waves way outside of the shorline. Both spots are shalow enough for this kind of action. Nobody would complain exept a few seals.
John Pollard 11/15/2008 04:06 PM * PREMIUM MEMBER - Real Name
Interesting article! I have been a Va.Beach/OBX surfer since 60's and watched the N.E.'s take big bites out of the coast. Currently, the N side of the Duck,NC pier beach is being devastated by the currents and NE'sters. I believe the only solution is eng. offshore reefs. How does that get done is the question. Town of Duck needs to hear recommendations. Army Corps research pier is the likely culprit also. ACE should take on the task as research project. SOS..SOS...Save Our Shore Please
rodney williams 11/15/2008 02:11 PM * PREMIUM MEMBER - Real Name
Small minded people from a small town. News flash. It is not the golden 60's any more. Just pop your head out of your bunker and look around. Enhanced recreational amenities (surfing, diving, fishing) while fighting coastal erosion is win/win. You're fighting the good fight Jose
Doug 11/15/2008 01:21 PM
I agree this Mount Reef stuff is total propaganda! I can see the reef from my house and I'm an experienced surfer with the skills to surf any wave. The Mount Reef is a total joke. It is described as a "slab" which is their excuse for producing a wave that on average breaks for around 3 seconds before mushing out into deep water. ASR sold our community the dream that the Mount reef was going to provide long peeling walls. It is a failure.
Jose Borrero 11/15/2008 12:28 PM * PREMIUM MEMBER - Real Name
View All Comments (89 comments)
James: Feel free to contact me if you want to discuss further. I don't mind having these discussions. 500 characters is rather limiting however.
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