Speeding at 150 knots thousands of feet in the air, an airplane sends out a laser pulse to a beach’s rippling sands.
From the location of the airplane, the travel time of the laser pulse to the target, and other factors, scientists can determine the height of the sand to within inches.
Enter a new age of coastal science.
Surveys of beach characteristics that historically took hours now can be obtained in seconds. The specially equipped airplane carrying LIDAR, or light detection and ranging technology, is a new tool in Professor Bob Guza’s investigations of sand movement and beach erosion. It’s part of a high-tech suite helping Guza and his research team at Scripps Institution of Oceanography, UC San Diego better understand shoreline dynamics.
“The technology is just staggering,” said Guza.
His research builds upon more than thirty years of wave science pioneered at Scripps through the Coastal Data Information Program, or CDIP. What was started by research engineer Richard Seymour as a more efficient way of transmitting wave data from ocean buoys has blossomed into a robust network that thousands of daily Internet visitors—from the weekend surfer to harbor managers to Navy navigators—now find indispensable.
Guza’s high-tech surveys and analyses are affording his team a new view of sandprocesses on Southern California beaches. The results could provide new clues about why sand disappears and reappears, and how pounding surf erodes beaches. This is vital information not only for scientists but for property owners and resource managers as coastlines are increasingly threatened by natural and man-made erosion, pollutants, and other hazards.
“Our CDIP team is now bringing together sandy beach observations with CDIP’s wave data into a more coherent program that’s about shoreline change rather than exclusively waves,” said Guza. “Now it’s a whole package.”
It just isn’t normal to see an ATV (all-terrain vehicle) rumble through your favorite beach in the middle of the night. But strange looks and the occasional suspicious inquiry by the authorities come with the territory for Guza’s research team as it conducts sand surveys at Southern California beaches.
Those who are taken aback by the ATV’s midnight rumblings are little aware that this is no ordinary vehicle for off-roading joy rides. The technologically tricked-out ATV is equipped with some $35,000 worth of instrumentation, including a computer and GPS sensors that measure sand levels five times per second.
The ATV maneuvers up and down San Diego beaches in giant lawnmower-like patterns during surveys, meticulously documenting tracts of sand at Torrey Pines, Cardiff, and Camp Pendleton.
To gain access to the widest swath of beach available, the surveyors are governed by the tides. Sometimes that means the surveys can be conducted under a noon sun in summer, but sometimes it means 2 a.m. in winter darkness.
In addition to the ATV, high-tech tools used in the Southern California Beach Processes Study include a GPS-equipped Jet Ski that gives researchers valuable data about sand levels just offshore.
With LIDAR, the researchers determine sand levels twice a year on beaches from the Mexican border to Long Beach, Calif.
Guza admits that part of his scientific investigations are driven by raw “curiosity run amok.” Even before he joined a leadership role in the program—indeed, even before starting his scientific career on coastal processes—he admits to a lifelong fascination with waves and beaches as a natural system.
He has studied beach erosion and sand levels as a long-term natural process, fluctuating through high-and-low cycles over thousands of years. In their natural state, beaches receive fresh sand input from rivers and cliffs. Today, however, especially in Southern California, beaches are deprived of this input because most rivers have been dammed and cliffs are being retained by armored structures and seawalls.
Recently, the science of understanding beach erosion has taken on new urgency as sand levels have plummeted in some areas dependent on beach tourism. Shoreline grains have become a precious commodity as millions of discerning tourists and their billions of dollars flock to beaches with inviting mounds of sand and eschew those without.
Like a detective using a new high-tech device at crime scenes to solve mysteries, Guza is using the precision of GPS to investigate the convoluted question of why sand appears and goes missing from one season to the next. He and his research team were able to follow the trail of a 2001 beach nourishment project that deposited 160,000 cubic meters (200,000 cubic yards) of sand at Torrey Pines. After a pounding storm in winter 2001, the surveys revealed that the newly infused sand retreated into the ocean to form a sandbar, but then moved back onto the beach the following summer, resulting in the much-desired wider beach.
But the surveys also can produce mixed messages. Surveys have shown that sand levels at Torrey Pines can change by six feet from summer to winter. After a November storm in 2001, the beach dropped 10 feet in two days. In contrast, over several years San Onofre beach 40 miles to the north has shown little or no change.
“Why?” asked Guza. “This is an interesting science question but it’s also a very interesting beach management question. Finding out why beaches change or don’t change could be valuable one day in finding a way to stabilize beaches that erode.”
The original idea for CDIP sprouted in Richard Seymour’s mind on his way home to San Diego from a conference on ocean waves in New Orleans more than 30 years ago. Sitting there on an airplane, Seymour kept replaying the keynote speaker’s main message over and over in his head. The orator chided the ocean community for its lack of long-term data from the coastline. More data on waves, he pleaded.
The appeal stuck with Seymour. An aerospace engineer-turned-oceanographer, Seymour and engineer Meredith Sessions had successfully developed new technology to use telephone lines to remotely communicate with a test buoy in San Diego Bay.
Following the conference, Seymour approached the California Department of Boating and Waterways about establishing a handful of wave-measurement buoys using the new technology. They bought into the idea and CDIP was born with a single buoy installed in Imperial Beach, south of San Diego, in 1975.
Two years later the U.S. Army Corps of Engineers became a funding partner and the program blossomed. In the years that followed, key personnel, including lead CDIP waves scientist William O’Reilly and program manager Julie Thomas, helped push the program far beyond its original scientific objectives.
Today’s network features about 20 buoys along the California coast, with additional stations in Oregon, Washington, Hawaii, and Guam. Instruments in Louisiana and Florida have begun a southeastern U.S. presence. Buoys transmit wave height, swell direction, and water temperature in near real-time to CDIP’s website. Backed by three decades of knowledge, the scientists and their sophisticated analytical techniques now deliver maps and models with present wave activity, also called “nowcasts,” as well as three- and five-day forecasts, all with uncanny accuracy.
The ability to deliver such precise knowledge of coastal conditions, it turned out, was a far hotter commodity than Seymour could have ever imagined. Hundreds of companies catering to surfing audiences now capture and repackage CDIP data. Harbormasters and Navy vessel navigators use its data about currents to route ships through coastal waters. On any given day, upwards of tens of thousands of users tap into CDIP data.
CDIP data even guided Navy search and rescue efforts after an Alaska Airlines jetliner crashed off Ventura in 2000, with scientists providing information about the height, direction, and frequency of ocean waves.
Troy Nicolini, warning coordination meteorologist with the National Oceanic and Atmospheric Administration’s (NOAA) National Weather Service office in Eureka, Calif., says he and his colleagues daily access CDIP data for wave modeling and forecasts.
“Most human activities occur within 10 miles of the shore, and that’s where you’ll find CDIP buoys,” said Nicolini. “In severe ocean conditions CDIP’s information on wave conditions, including wave period and height, are important for us to evaluate whether or not to issue warnings such as high surf advisories to the public.”
The coastal science that CDIP helped push forward stands to open new doors to the beach of the future.
The program’s wave knowledge base is allowing Guza to study surf zone currents and how pollution moves across the shoreline, valuable information in an era in which human-produced contaminants frequently afflict the coast.
“The beach is constantly in motion, whether it’s eroding or accreting, so in the future I see a very tight meshing of the wave data component of CDIP with both the science and engineering of the effect of these waves on the coastline, whether it’s inundation, erosion, or structural damage,” said Seymour.
The future also brings CDIP’s research to bear in examining how the coastline might transform in a warming world. Last year’s Intergovernmental Panel on Climate Change report indicated that sea levels will rise between 0.2 meters (7 inches) and 0.6 meters (23 inches) by the end of the century. A recent analysis by Scripps scientists suggests the rise could be even greater in that time span, ranging from 0.5 meters (19 inches) to one meter (39 inches).
“What will the shoreline look like 50 years from now?” asks Guza. “CDIP is getting involved in trying to understand the range of responses the shoreline might have to the range of sea level scenarios that are emerging. How do we maintain sandy beaches in the face of rising sea level?”
Guza believes the time is right to find out—for science and improved beach management—and new technologies will help him get there.
“In order to understand what might happen in the future, a prerequisite is to understand what is going on now.”