Scripps Institution Scientists Study Imperial Beach As Sea Level Rises
January 30, 2019 1:55 p.m.
San Diego scientists who are interested in rising sea levels are spending time in the coastal community of Imperial Beach the low lying city is nearly surrounded by water and faces immediate challenges from a changing climate. Hey PBS environment reporter Eric Anderson has details.
Imperial Beach lifeguards and Mayor Serge De Dina were up at dawn on a recent morning keeping an eye on the ocean but not a lot we can do at once as the ocean reaches a certain level in the surf for certain height.
Not much we can do.
Seasonal high tides and an active storm cell were working together to blast coastal barriers designed to keep the ocean at bay. Large rocks didn't always succeed. The storm fueled waves regularly washed over the coastal reinforcements. Public safety officials did what they could to protect the people living here. They got out and they warned them of the danger. Once that water comes over the seawall and floods the local streets here it's still need somewhere to go and much of it ends up right here in the Tijuana River estuary.
The estuary absorbed the overflow but the capacity is limited.
This is likely to happen much more often in Imperial Beach and other low lying communities. As sea levels go up. Mark Merrifield works at the Scripps Institution of Oceanography so we know sea level is going up.
But as you add on these wave events what does that combined effect look like.
He runs the Center for Climate Change Impacts and Adaptation and he wants to understand how these two events. High tide and big waves interact. He's interested in everything that's happening during this event.
Sea level is so high and the estuary where it normally would rain that it's just backing up the water. So that effect is also important to measure in the document. And. In a way this is almost like a natural laboratory for that sort of thing.
But it's the situation in the ocean that's most interesting to him he says. Researchers know a lot about local tides and they have data on storm driven waves.
But there's a gap in the information when those two things happen together trying to get the waves from offshore to onshore during these kind of energetic wave events. There's not a lot of data so that's why this data is so important to get that combination out. To. Really map out one of these events in detail.
Merrifield is tracking this event from many perspectives. There is an offshore wave boogie. There are monitors buried in the sand and even a drone flying overhead. And on this second floor condo balcony researchers are using a machine that takes specific measurements using pulses of light to calculate the range of nearby objects. This is a two dimensional view.
Looking straight out at the ocean.
Marine Technician Lucian Perry says the light our equipment is sophisticated enough that it can track and record many individual waves. It can also draw a three dimensional picture of the survey area. We put it a three dimensional view. And. These are the waves coming in. All this information will help researchers build better predictive models about events that will likely occur more often. As sea levels rise. Imperial Beach Mayor Serge Giardina says knowing more about these events will help city officials plan.
So right now immediately what we do with our sewer pump stations what we do with our roads we our electric outlets and working with Eugene on that. We have a school that's on the bay front and then how we going to actually deal with mitigating rising seas and increased erosion.
Rising sea levels are not something the city can ignore because Giardina says the low lying community is surrounded by the ocean an estuary and San Diego Bay.
We're going to have to face some tough choices and what we do to address protecting our public beach and public access so we're looking at natural solutions and then really protecting our infrastructure.
Dina says public property is the city's primary concern but private property owners there also have some decisions to make. As water pushes against the city's boundaries.
And joining me now is Cape PBS environment reporter Eric Anderson. Eric welcome. My pleasure. Do researchers have a good idea how much sea level has already risen in Southern California coastal communities like Imperial Beach.
Well we know that the sea level has gone up I don't think they've exactly quantified it. The thing about the sea level is that it doesn't stay static right. The sea level is constantly going up and down whether it's because of tides whether it's because of wave events and just normal fluctuations so that's a little harder to measure. But what we do know for sure is that there is going to be significant sea level rise along the southern California coast and communities like Imperial Beach. This is not something that can run from this is something that they have to deal with head on.
Now climate change is not just expected to create sea level rise it's also expected to create more severe storm events. Does that make the information being gathered on tides and waves even more crucial.
Yeah that's really kind of the gap in the information that that we heard Dr. Merrifield talk about was there is a lot of information known about the tides. We measure them you can call up a tide chart that can give you a forecast of what the tides are going to be months and months in advance. So we know a lot about the tides. We know a lot about wave events right. We've studied storms and and what that does to the ocean surface is the wind in the way and the swells kind of kind of work together to kick up the waves.
But we don't know how those two things act together. So if you have a tide event that is higher than normal and you have a big wave then on top of that that's kind of where the gap in the knowledge is and that's what Dr. Merrifield is trying to to kind of paint in a little bit to gather some information so they can start to develop models that will help them with things like prediction.
Now you mentioned the beach front streets that were flooded during the storm. Is there that something that's always happened there or has that been increasing an Ivy over recent years.
Yes and yes that's exactly right. It's something that has happened before the strip of land where we were recently was along sea coast drive which is in southern Imperial Beach. It's right along the beach. So the condos there look out over the beach. But if you look back the other way they're looking at the Tijuana River estuary and there's a small road that runs on the back side of those condos. That road does get flooded. It has happened. The thing is as the climate changes as the sea level rises that will happen more frequently and it might be more dramatic as well.
There may be higher tide events there may be a bigger wave events and so the impacts could be good. The Scripps Institution of Oceanography is working with Imperial Beach to kind of help them identify some of the instruments that they were using during this event. Are there when these events are not in place when these events these high tide and highway events are not happening and what they hope to use them for the wave. Bouie off shore and the sensors in the sand is to help them understand when this confluence of events will occur so they can let the Imperial Beach city officials know about that then it's going to be happening and they can then react accordingly.
Now we're expecting another rather big storm. It's in the forecast for tomorrow. So to the Scripps researchers gear up to monitor the waves in any way before the storm event they're not down there just during the storm events.
Now this recent king tide and storm event was a good confluence that kind of brought them down there in force if you will. They put a lot of their resources at play but they're monitoring the situation all the time they have an ongoing project with Imperial Beach and a research project that allows them to see what goes on there. So they're going to learn things about that. They don't kind of put on the boots so to speak just because a storm event comes in. It's something that they're watching over time and they're hoping to get information that will be valuable over time.
So I want to talk to you about the news today the city of San Diego has joined the lawsuit by the state of California against the federal government for sewage flows in the Tijuana River Valley. What does it mean that the city of San Diego is now party to that suit.
Well I think it means you know on the surface that the city recognizes that this is a problem and they recognize that legal action might be the avenue that they can use to help solve this problem. It represents another big player in the region joining in the battle. You'll recall that the initial suit was filed early last year by Imperial Beach Chula Vista and the Port of San Diego. They basically wanted the federal government to not only address the flows coming through the canyon collectors and into the international wastewater treatment plant but also some of those sewage flows that got into the t want a river valley.
They want the federal government to fix that. The regional board filed their suit in September and their suit looks primarily at those collection systems that are in place in the canyons and at the wastewater treatment plant. And not so much at the Tijuana River that as it runs through so it's the scope of that state lawsuit is a little bit more narrow. But I think overall the idea is the same. Both of those lawsuits and a Surfrider lawsuit that was also filed on behalf of people who swim in the ocean. They all want the federal government to basically take responsibility for pollution that's moving into U.S. coastal waters through the Tijuana River Valley which is in the United States.
Does the fact that the city of San Diego is now party to that suit strengthen the lawsuit in any way.
I'm not sure that legally it changes the position. It's sort of like filing an amicus brief it's like saying look we support the action that is being requested by the state of California. I think from a public relations standpoint it does mean a little bit more. It means that the city is now engaged in this battle for cleaner water and it also raises questions about the county of San Diego. This is something that clean water groups have been talking with the county for some time and the county has not quite decided to take that step to join any of the existing legal action that's in place.
I've been speaking with KPBS environment reporter Erik Anderson. Eric thank you.