USC Experts Monitor Coastal Waters

09/11/08
Using radar, underwater gliders and other sensors, faculty and grad students survey the shores of L.A. and Orange counties.
By Richard Hoops
Burt Jones, left, aboard a research vessel with a device known as a CTD a conductivity, temperature and depth sensor. Jones will use CTD sensors on moorings that are to be deployed this fall in the Santa Monica Bay. With Jones is engineering technician Carl Oberg.

Photo/Zach Johnson
Public health officials in Southern California will have a better picture of water quality off the coast with the help of sensors that are being installed or deployed by faculty and graduate students who work with the USC Wrigley Institute for Environmental Studies.

The project led by Burt Jones, a research associate professor in the USC College’s Marine Environmental Biology program, covers much of the shoreline of Los Angeles and Orange counties.

Jones and graduate students in his lab have assembled a suite of sensors that include six radar installations to monitor water currents, two underwater “gliders” that carry thermometers and other gauges, and two buoys that will be anchored offshore and fitted with gear to analyze water quality.

“We’re implementing a ‘real time’ observation system for Los Angeles and Orange counties,” Jones said.

Jones said the data from all these devices will be used by people who monitor coastal waters to protect human health and by scientists who want to know why coastal water conditions change. These devices are particularly valuable in that they are much less expensive than sending people out on ships to collect water samples.

Radar Installations

The Jones lab has installed six radar units along the coast that are part of a much larger project called the Southern California Coastal Ocean Observing System. The project provides a constant stream of data about ocean conditions from the U.S.-Mexico border all the way to Point Conception in Santa Barbara County. The USC portion of that project covers the waters from Newport Beach in the south to Point Dume in the north.

Each of the radar units has two whip antennae that bounce high-frequency radio waves off the water surface to analyze the direction and speed of surface currents. They feed a steady stream of data to computers in Jones’ lab on the USC campus, and the computers determine the movement of water beneath the waves. The ongoing analysis of surface water currents is made public on the Web site of the Southern California Coastal Ocean Observing System.

“The utility to the user community is the ‘real time’ availability of information,” Jones said. “If there’s an oil spill or if a boat capsizes, emergency personnel can see where things are heading because we’ve measured the surface currents in real time and can show their direction.”

Underwater Gliders

Jones and his colleagues are looking beneath the ocean surface with self-contained “gliders” that look like torpedoes with wings. The gliders carry sensors, two small computers and a satellite telephone. They’re programmed to record water conditions while they glide downward to a predetermined depth and then float back to the surface. At the surface, the devices call home, report their findings and reorient themselves with GPS before the next trip down.

The gliders operate without propellers. They take on seawater at the surface and as they get heavier, they sink at an angle. At a pre-determined depth, a small motor will push the seawater out, and the glider will get lighter and rise to the surface. As this routine continues, the glider takes a path through the ocean with a saw-tooth profile and the simplicity of the propulsion lets a pack of batteries power them for up to three weeks at sea.

“They don’t go fast,” Jones said, “but they can stay out there a long time.”

Jones and the students in his lab are working with other USC faculty to use the gliders on two projects along the coast. One is in collaboration with the Southern California Coastal Ocean Observing System to monitor a plume of treated wastewater near Dana Point.

The other, funded through the National Oceanic and Atmospheric Administration, will document the occurrence of harmful algae blooms and the conditions that precede these blooms in nearshore waters.

The latter project involves USC computer scientist Gaurav Sukhatme and USC biologists David Caron and Astrid Schnetzer. In February, they will launch as many as four gliders in the San Pedro Bay to collect data between the Port of Los Angeles and Dana Point. The gliders will look for algal blooms and inorganic nutrients. While they are on their missions, the USC researchers will take water samples from boats and piers to determine if algae blooms are present and if they are harmful.

“This is the first project of its kind in this region,” Jones said. “And it is a complete research project, not just a test.”

Moorings

Jones is working with other sensing devices that monitor water quality while submerged. They will be attached to buoys and anchored in the Santa Monica Bay to provide a constant stream of data on water conditions.

Jones will help install two of these moorings this fall near Redondo Beach and El Segundo as part of a project that involves USC biologist Dave Caron.

Jones and Caron want to see if these floating sensors will detect water conditions that precede blooms of harmful algae. The work is funded by the West Basin Municipal Water District, which is testing pilot desalination plants along the Santa Monica Bay.

“They’re concerned about harmful algal blooms that might release toxins and affect the water supply,” Jones said. “The information from the buoys would give them a warning when they might need to shut down their water intakes.”

Each mooring will have two packages of sensors, one attached to the cable near the surface buoy and one near the anchor on the ocean floor, and they will transmit data to shore using a radio connection to the Internet. Jones said this telemetry system is much less expensive than the satellite phone system on the gliders, which can cost as much as $800 a week.

Summary

“By the time we get all this done, we’re going to have three ‘real time’ ocean monitoring systems in the water,” Jones said. “We’re developing an ongoing ‘live’ view of the ocean where these sensors are always on. We can use the radar data and the glider data to look at things that are moving in the water and then look at the moorings to see when they actually show up.”

The suite of sensors will help people better understand the effect of large urban areas on coastal oceans, Jones said. For example, the sensors help scientists distinguish between natural and human influences on water quality, especially as they affect the toxic conditions that accompany the blooms of certain types of algae.

Jones said this kind of work involves a lot of investment in hardware but eventually it pays off. These devices can take the place of some of the sampling that people now do from ships, so they help researchers avoid the expense of fuel and shiptime. The gliders can operate for weeks on a handful of batteries instead of hundreds of gallons of fuel, and Jones said there is another advantage “they can stay out during storms and they don’t get seasick.”