Field Trip to the Congo, “The River that Swallows all Rivers”
The Lower Congo River is home to a uniquely high diversity of fish species living in isolated populations in specific locations. U.S. Geological Survey South Carolina Water Science Center Associate Director John Shelton discusses key features of the river which may be causing this trend and their implications to the River’s ecosystem.
John Shelton: This is A Field Trip to the Congo – Hydroacoustic Measurements in "The River That Swallows All Rivers."
We'll talk a little bit about hydroacoustics. Hydroacoustics is just the use of sound to measure primarily water velocity. We'll get into that. That was my primary part of this program.
This is the outline I'm going to try to stick with and brush on. Each of these topics will give you a brief overview of the Congo River Project and its history with the American Museum of Natural History in New York.
We'll talk about some of the field data we were able to collect. And while we were doing that, we're doing primarily for model predictions. We had a couple of different hydrologists in the country who had run models on the Lower Congo River and thought it would be just outstanding if we could get those folks on the ground to do some verifications of what they had predicted.
And then, my part primarily is this third bullet, the acoustics and water quality measurements. The primary purpose of the research team was just first, fish diversity definition. The project was funded through the American Museum of Natural History's Ichthyology Department and Dr. Melanie Stiassny is looking at all of the different fish species in the Lower Congo River. So we were there to support her.
OSW time test is my Office of Surface Water and I just used an instrumentation type test. They thought if we had the opportunity to work on a river of this magnitude, if we can do some pretty in-depth testing of the equipment we were using too, we'd work on that.
Congo River is also one of the most turbulent rivers in the world. And we had a great opportunity to be able to measure and define turbulence, to look in to the actual velocity structure that's going on and then see what we can look at, three-dimensionally.
QW field parameters and samples, that's water quality sampling. And that was actually my boss' idea. He said, "Look, if we got the opportunity to go over here and do this work for a month, we need to collect as much data as we can." So he funded that to look at the different tributaries of Lower Congo and the quality of water that they're pumping in.
And the last two over on the right hand side, bathymetry and discharge, those were my responsibilities. Bathymetry is looking at the bed contour of the river. We wanted to look at the three-dimensional contour map of the river bottom and then compute the total flow line that's going down the river.
This is a shot from the American Museum's Congo River Project homepage. I encourage you to take a look at. It's a National Science Foundation project to look at the diversity of fish in the Lower Congo River. Specifically, what Dr. Stiassny is looking at is this. It's got this vast species count in the Lower Congo but they're incredibly segregated. You have this population of fish that you'll find in one location and you'll find a totally different species even the other bank, or just a short distance downstream. So not only is she trying to identify them, she's trying to figure out what features of the river are keeping them so isolated.
This is the Congo River Basin. It's a huge barrier in the center of the African continent. The outline here is the drainage basin. The majority of the basin takes up the country of the Democratic Republic of the Congo, which was formally Zaire probably 20 plus years ago. So you have the Democratic Republic of the Congo here and on the other side of the river is just the country of The Congo.
That being said kind of related to what I said earlier about all these fantastic countries I get to go to. I was talking to a friend of mine at headquarters, and he said, "John, you understand that any country that starts with 'The Democratic Republic of' is probably not one you want to be visiting." I said, "OK." Actually, we had a pretty good visit. We did have a few encounters that I'd get into later.
I said this project was funded primarily through the American Museum of Natural History's Ichthyology Department. National Geographic did tag along with us and made a National Geographic Explorer episode out of our research. So funding came from them as well. That made it even more interesting. So through this presentation, I got a couple of video clips through that Explorer episode that will kind of enlighten you a little bit more about what we're able to do.
Here, I'll start by saying that I'm a hydrologist. I've studied water for several years but don't claim to know anywhere near enough. And during the course of this presentation, I'm actually going to talk a little bit about geology and a little bit of bit about biology, but I'm no means an expert on either of those subjects.
But what these cartoons are showing here is the history of the Congo River Basin. There's speculation that somewhere between 400,000 years ago and 35 million years ago, the Congo River Basin was actually a centrally-drained basin, where there wasn't a major outlet to the ocean on the West Coast. So you can see here, there's a bunch of internal drainage going on but the Congo, at that point, did not reach the Atlantic Ocean. Somewhere during that time span, there is theory that says there was some catastrophic, geologic event that took place, that ripped the western part of the continent apart and allow the whole drainage to exit to the ocean on the west side.
When you're in that area, it's very obvious that the river for that last 1 to 200 miles is entirely different from the whole rest of the basin. Much of this part of the Congo from its head waters in the central part of the continent, flowing north down to around Kinshasa, is very incredibly wide, relatively sluggish. Then, just below Kinshasa, the whole dynamics of the river change. It gets incredibly narrow, goes through some incredible elevation changes and has some of most turbulent waters in the world.
Looking at it again, you can see that little circle. It's called Pool Malebo. At that point of the river, the river's about 15 miles across, and the speculation is that it was somewhere around that point that the plug in the river existed. That's prior to, whatever, 400,000 years ago. Prior to that point, the river to the west wasn't even in existence.
So that's where we're starting, what we call the Lower Congo River – from Pool Malebo forward. You zoom in a little bit, you can see here, Pool Malebo is right at Kinshasa which is the capital of the Democratic Republic of the Congo. This map is actually saying Zaire. On the side, it's just Congo. It's the political boundary for several miles and then the DRC's boundary goes above the river, midway down.
If you look, this is an elevation map, showing the change in river elevation over distance. So you get Pool Malebo and then looking at the 350-kilometer range from Pool Malebo down to Matadi which is here on the map. You have these two extreme changes in elevation. This change is somewhere in the vicinity of Livingstone Falls. And this change is going to be the area called Inga. Much of our study took place from just below Pool Malebo through Livingstone Falls into this area here. Once you get in to Inga, there's no navigation whatsoever.
These are some of the fish that Melanie and her folks were collecting. As of 2008, they had identified approximately a 135 different species and that number was rising with every trip. Of those 135 species, 30% are found only in the Lower Congo. No other place in the world where this fish found and there's some pretty interesting looking creatures here.
We'll take a little bit of look. Just looking at some of the species here – primarily, this is all sequenced. We're looking at, if Pool Malebo's here, the green dots represent the Lamprologus werneri and they're found only in that reach. Once you pass this area of the river, they're not there anymore. Then you pick up another specie, the tigripictilis. And they're found from just below where werneri ends to just above Inga.
The interesting story is the red dot there in the center. The red dot is Lamprologus lethops. And if you look at lethops, you can say they're all cichlid. They're all same body structure. He has the unique identification of being totally white. There's no pigment there, no eyes, skin flaps for eyes. And so, all these features are indicative of a depth dweller. Some fish that lives way down deep. He's not in the sunlight. It's so dark that there's no need for vision.
And the story here is they're only found in that one area. The even more interesting part of the story is that they never found a live specimen. They were only finding dead specimens of this fish. They couldn't find it. And they were collecting them primarily through the local fishermen. They weren't able to collect them with their typical collection methods. The fisherman would bring them in because they knew they had a bounty. They knew they'd get paid if they brought this particular species in.
Until one year, a fisherman brought Melanie a fish that was actually still alive. It was dying, dying very rapidly. And as she was holding it, she watched and she could see these air bubbles form underneath the skin of the fish, in its eye pockets and right there on the top of its spine.
So theory is then, that if this is a depth dweller and these air bubbles are formed and it's very similar to what scuba divers are going to experience on rapid ascent. Rapid ascent, it's called the bends. It's going to be failed decompression syndrome where you have your body under so much pressure that you have to give it time to equalize and off-gas as you ascend. And if you ascend too quickly, then the air bubbles form in your blood and it'll kill you.
So that's what their speculation is that was happening with this fish. So what Melanie really wanted to find out was if we could identify, through the instrumentation that we were taking on the Lower Congo, if we could identify the reach of the river that would have this extreme depths that could accommodate this fish and if there were hydraulic structures present that would, for some reason, make this fish come to the surface. What was going on that would catch this fish and send them to the top?
That gives you a little size or perspective.
Field verification and hydroacoustic measurements, this is where my job came in. This was my area of expertise. We actually kind of broke this section up into two different teams. First of all, we had a seven-man kayak team. They were 100% funded by the National Geographic. Their primary responsibility was to collect videography and photography down about an 85-mile reach of the river.
This particular reach of the river went from Malebo Pool, just below Kinshasa, down through 85 miles and had never been successfully navigated. There was a team in the 80s who tried to navigate that same reach and they were never heard from. They didn't find them after that.
Part of this team was Trip Jennings. He was one of the National Geographic's Explorers of the Year. And their primary purpose is to—they go all over the world kayaking these crazy rivers just to bring the importance of water quality and the world's water supply to the forefront. They want people to see what's going on and just have a great attitude about what their working on and a great scope of work.
They were also excited because if they were going to get to do this great run down 85 miles, they wanted to know what they could do to help the science team collect any valuable data. So we decided to rig one of their boats with an echo sounder, GPS and data logger so we could collect single-line bathymetry track down that 85-mile reach.
The second part of the hydrology team, if you will, is just a two-man team which was myself and Dr. Ned Gardiner who at the time was with the American Museum. And we were primarily tasked with velocity and bathymetry mapping. Everywhere that we were collecting fish species, they wanted to know what the bed forms were and what the flow distribution over those areas were.
If you look at this picture, I think, if you see the little black circles, those were the first two kayakers down that reach of the river below Malebo Pool. They actually drew straws to see who the first two would go and to pick the lines and see how navigable it was and actually be the first two successful kayakers who could live to tell the story below Malebo Pool.
It's really interesting here because we're at a village and so all the local villagers come out to see what these Americans are doing with the little plastic boat. And you could see in their faces that they didn't expect to see these guys again if they were going to put these little boats and go down the water. And so when they made the mile run and came back to the bank, the whole village just erupted in cheers and shouts. They didn't even let the gas get out of their boats. They reached down and grab the gas in their boats and lifted them up in the air. It was quite a sight, it was lot of fun.
This is the first of three little video clips – gives a little more perspective on the river itself. The Explorer episode is called "Monster Fish of the Congo". I'll clarify that a little bit because you just saw the little fish that were sequenced that were like, yeah. Monster—there was another research team looking at the Goliath tiger fish above Pool Malebo. The Goliath tiger fish is huge with real sharp teeth and, I guess, piranha-like appearance almost, but just huge and wicked.
National Geographic, of course, knew they couldn't call it the little white cichlid fish of the Congo. It wouldn't quite get the same response as Monster Fish did. But this is the brief, a couple of minutes.
[Start of Video Clip]
Announcer: The Lower Congo River's rapids and whirlpools make much of its length inaccessible, but Melanie has brought a secret weapon – a team of world-class kayakers led by one of National Geographic Adventure Magazine's Adventurers of the Year, Trip Jennings. They will brave the Lower Congo's raging waters to collect depth and hydrology data in places no one else can go. All while attempting an historic first – a four-day 85 mile journey down the Lower Congo in kayaks.
Using kayaks to map a river is an experiment in itself. Charged with retrofitting them are geographer, Ned Gardiner, and John Shelton of the US Geological Survey.
Video Speaker 1: We're better than something. These seven instruments, they weren't designed to be put together in this way, on this platform, in its confined space.
Announcer: They're fitting Trip's kayaks with scientific instruments: GPS to chart positions, an echo sounder for measuring depth and a data logger to store all of this formation. These tools will provide the first glimpse of what lies beneath the waves of the Congo River.
But working in this environment with instruments this sensitive is a gamble. That's why they chose Kinsuka Rapids for the test run, one of the roughest stretches of white water on earth.
Video Speaker 2: ...
Video Speaker 3: Yeah, you like it?
Video Speaker 2: Look at that thing explode. Look at that.
Announcer: The water collected by the vast Congo Basin drains into this bottleneck. The flow is more than a million cubic feet per second, enough water to fill over 800 Olympic-sized swimming pools every 60 seconds. If the equipment survives here, it's likely to make it through the 85-mile journey ahead.
[End of Video Clip]
John Shelton: OK, you heard what he said last, "If the equipment survives here, it's likely to make it to the 85-mile journey ahead. That was Peter Coyote's foreshadowing of what's to come.
So we'll get back to that. Here's our primary kayak. The light globe of course is the differential GPS connected to the yellow brick. That's the processor. It also had an echo sounder that's mounted in the hole, shooting through the hole to get depth data on one-second intervals. All that were being merged into a data logger, in hopes of getting that beautiful bathymetry flat down an 85-mile trek.
Additionally, if you look in the right hand photo, there was a camera mounted on the bow of the orange boat. And in the blue boat, the bow of the blue boat had a helmet-cam. And some of the footage that these guys were able to collect down that stretch of the river was just amazing. It's mind-blowing.
In addition to all these gear, we'd also given them water quality sampling supplies that they were storing in their bow. So everywhere there was a tributary coming in, they were collecting water quality samples and doing some processing. They had to have different supplies for that.
So all these together, in addition to the power that's having to power all these stuff, we were adding a tremendous amount of weight to their boats that they weren't accustom to and we were also taking up valuable space for all the other supplies that they were accustomed to having with them.
Great group of guys, they have a great attitude, and they did a fantastic job. They started their 85-mile trek just below Kinshasa, went 85 miles, ended in this area which a little village called Pioka, which is just below the Livingstone Falls. The initial trip, 85 miles, was supposed to take four days.
On the morning of the third day they woke up to a group of militia that was on top of them, equipped with automatic weapons and shot guns and laid them all out on the beach, and commenced to rifling through their gear, taking whatever they wanted. The team presented their official papers that said they had every right to be there but the team was English-speaking and the militia was French-speaking and that didn't help the situation a lot.
So it got pretty heated. At one point, the militia told the team to get up and they were going to march them in to the woods. And at that point, the team decided that probably wasn't their best option so they crossed their fingers and said a quick prayer and turned around and walked to the kayaks, got into the kayaks and paddled away. And no problems, it was all over. Needless to say, the four-day trip turned into a three-day trip. They weren't about to stop again. They made it to our camp. They told us their stories and it was a like big welcome home.
We were incredibly pleased to see them but we were also excited to see that data that they'd collected down the 85-mile trek. So we took the data cards out and started to load them and realized almost immediately that we had not collected the first piece of information whatsoever. It failed. Something had failed.
I'm a field guy. I'm an instrumentation guy, and I designed the whole system. It was just, I thought it's going to be the greatest. And of course, when I didn't even get one depth reading for 85 miles, I was just devastated.
So I was kind of scratching my head, trying to figure out what to do. And the kayak team, they call me McGyver, by the way. And they said, "McGyver, come on, there's got to be something you can do. You got to fix it." And we thought about it for awhile. And we finally said, "We know we can do this and this and merge some pieces of equipment together. But I mean it's…" And they're like, "Mo' man, we only get to go to the Congo once. It's 85 miles. If you can get it working, we'll do it again."
So they did. We rigged it up and got everything working and they took the jeep ride all the way back to Kinshasa which is a day trip all in itself. And they did it the second time. And this second time, they made the four-day trip which had turned into a three-day trip in two days. They made it in two days and they stayed on the island in the center of the river.
John Shelton: They were not going to stay anywhere with land access.
So two days later, they were back with full data card and we had a fantastic data set that documented depths greater than 700 feet in parts of the river. We did a little digging in trying to document the deepest river in the world. It's a little more difficult than it sounds. The best source we could find, NASA, gave credit to the Yangtze somewhere in the 400 to 500-foot range. So we were pretty tickled with our 700-foot range in that reach of the Congo.
Moving on, we'll get to 'John and Ned's Excellent Adventure'. This is the second part of the hydrology team. This is Dr. Ned Gardiner here on the gunnels. This was our primary work boat. It was about a 40-foot pirogue. Pirogue is carved out of a single tree trunk. Forty-foot long, has a 25-horsepower outboard on the back.
And they told me that was the vessel we'd be working out on before I left and I honestly thought they were kidding. I was going to work on the second hardest river in the world in a carved wooden canoe at 25-horse outboard line. But we did. And it worked well. The fisherman we had, the local fisherman, was our pilot.
The orange boat you see, in the center of the hole, that's our Acoustic Doppler Current Profiler. That's what we used for depth and velocity measurement. And this will give you a little more insight on that.
[Start of Video Clip]
Announcer: John and Ned set out to document the barriers that are keeping Melanie's fish population apart. They brought the right machine to do it. Meet the Acoustic Doppler Current Profiler or ADCP, for short.
On board this miniature trimaran are four acoustic transducers. When activated, they fire acoustic pulses through the water to chart the floor of the river and record the speed and direction the water moves.
Video Speaker 1: They're marking it not like how we see it. What they're doing is they're looking at it like a fish. They measuring depths, velocity, temperature, conductivity, pH, dissolved oxygen. How much oxygen's in the water? That's very, very critical for fish.
[End of Video Clip]
John Shelton: That's kind of what we did – day in, day out – for the month that we were there, sitting in the boat, toting the ADCP and collecting the water quality samples.
This was our very first measurement. This is just a screen capture. I'll give you a little more information. This is at the Luozi. First measurement was 1 ¼ million CFS. And Ned, my partner I was with, laughed at me because actually, when we crossed the million CFS mark I had to take a picture of my laptop screen. Because I'm a field guy, a steam gauger at heart and joining the "Million CFS Club" is like a milestone. So, to be able to do that on that trip was just fantastic.
It was 1 ¼ million CFS. The river at that point was about 1 1/3 miles wide, about 80 feet deep. And if you look, what we were primarily concerned with is this plot in the lower left. This is like a slice of the river, where you're standing on the river bed, the black line being the bottom.
And then the color contours are representative of the velocity. So you had the reds and yellows representing the fastest velocity near the surface. Kind of in the deepest part of the river, typically where you'd expect it. But what was impressive to the ichthyologist is this section here, where you get the blues and purple that are representative of near dead flow, almost nothing. And then you can move over just a foot and suddenly, you're in water that's flowing seven, ten feet a second.
So you have to think about that from a fish' perspective. If the fish is accustomed to hanging out in slow-falling water and they moved a little bit in the wrong direction, they'll get jetted to the ocean. So being able to define that in that particular location was good.
We moved from Luozi upstream to Pioca. All right, I got to tell you a story about this guys, too. His name is Darak. And you can see in this trip, we were actually in a smaller blue pirogue. The blue pirogue was not much wider than your hips. You could just barely wedge down in there.
This is where we experienced the first whirlpools that we haven't seen before. We have four men in this boat. We had Darak, myself, and Ned and in the very front of the boat was the National Geographic producer who was turned around, facing the rear. I was a little nervous. It was my first time in a water like that. The boat was pretty tipsy. It was old and crooked. I was white-knuckling most of the trip.
As we're going up river, Ned, in a typical Ned fashion, he was playing his banjo. He was playing his banjo, just kind of looking out across the left bank and I was looking at across the right bank and this massive whirlpool opened up. There's this huge black hole probably 20 feet in diameter that you don't even see the bottom of it. And I'd never seen anything like that. And I yelled and I pointed to get Ned's attention to show him this black hole. And Darak, who doesn't speak English, obviously thinks I want to see it up closer.
Audience: He was at play.
John Shelton: Yeah. So he hit the outboard, and the boat's long enough that when you turn steering like that, it doesn't really heave it, it just kind of rolls. So when it rolled, all our gears started falling all over the place. We're grabbing hold of the sides for dear life.
Finally, the boat rights itself and everybody's still alive. Ned said, "That was really close." And the guy from National Geographic who's facing the rear said, "Actually, it was too close because we lost our boat driver." And so I turned around, and Darak is in the whirlpool with eyes as big as saucers flaying his arms. And we're just motoring upstream with no captain.
So I jumped in the back of the boat and very slowly, turned the boat back around and we grabbed Darak and pulled him back in the boat. And you can tell, very well, that this picture was taken after that event, because Darak was wearing a life jacket and he did not take his life jacket off for the remainder of the trip. Ned and I did not ride with Darak for the remainder of the trip.
Anyway, it was a good story.
This is at Pioca. This our typical camp. In this picture, I know it's really hard to see, but if you see the white line that goes across the river, that's part of Livingstone Falls. It's actually, there's series of little falls through there. But as we were approaching, I saw that in a distance. It took me forever to figure out what that was. It was just so odd to see that white wall across the river upstream. It wasn't so big that our kayakers could navigate across it. They did come through the falls and this is where we met them.
This is my tent of the equipment there. Every night, we tie the equipment together. That's probably about a $150,000 worth of instruments that we tie together every night and pull the rope into my tent at night and tied to my shoes. In hindsight, I'm not really sure why I did that. I mean, if my shoes went flying out the tent, I guess I know it was gone but I certainly wouldn't go and chase them. But we had no problems whatsoever.
We had guys like this. You can see he's got an automatic rifle strapped to his back. But he was just curious. He came down and visited with us one day and wanted to see what was going on and checked out the pictures we were taking of the river. So it was no problem.
We did have processing issues. This is something we thought long and hard about before we left on the trip. Because we knew we were going to be out on the banks of the river for a month solid, with a lot of equipment that was battery-powered. So we had to be prepared taking out batteries to keep enough supply or keep them recharged.
So in this picture, you can see we have a foldable solar panel. We had a couple of those. So every minute that we weren't using the equipment, we had to make sure we had everything on charge to keep it up for the following day. If we did have a vehicle access, we even run it off the alternator and keep batteries charged that way. And if we weren't having power issues, we had few bug problems.
This was one night. I'm not even sure what happened. But this night, they came out and force and we were trying to process using the laptops. And, of course, the glow of the computer screen was just a magnet. So there were millions and we cut short that night.
We moved from Pioka downstream to Bulu. You can see, we met the kayak team at Pioka. So they all boarded the big red pirogue. We had the whole team on board. Some of their kayaks were strapped across the front and we moved downstream to Bulu. Bulu is the area where the Lamprologus lethops, the little white, fish had been found. So we were excited to get there and do some work.
This was our typical setup. That's Ned standing near the bow. The staff in his left hand is actually a series of little aluminum pipes that are pieced together with that echo sounder transducer on the bottom of it. So we were collecting bathymetry data there, as well as bathymetry from the AACP and the telemetry in on the right side.
We had a water quality monitor over the bow of the boat collecting instantaneous water quality data. And then, of course, the solar panel, we had one in the boat too keeping everything charged during the day. Everything is coming back to the laptop in the center of the boat.
So what is the deepest river? This was an area just around Bulu where lethops was found. In this particular area, you can see in the tabular window on the left hand side, AACP is a four-beam transducer system. So you got four beams rotating up ahead at 20 degrees. And so at great depths, you can imagine that four beams are spreading out on quite a footprint, but you can also say that we're ranging in depth from 300 feet to 500 feet, which kind of gives you an idea of the really irregular nature of the channel.
You have this just massive stone chimneys coming out from the bed. You have this incredible drop-off, so it's 200 or 300 feet at the time.
You can kind of see those on the top plot where the beams are able to show you the chimneys and the rises. The bottom plot is actually not looking at AACP depth. It's looking at the echo sounder depth. And the bottom was so irregular that the echo sounder just wasn't functioning. It wouldn't work.
This slide is titled "Velocity Distribution Relearned" because I did most of my hydrology and hydraulic studies inland, in Tennessee. In Tennessee and South Carolina, your water is going to run downhill. The fastest water is going to be near the center of the channel towards the surface. Not so in the Congo.
If you look the top plot is actually, it's that component of the water that's flowing in the up direction. So we're looking only at upwellings or downwellings in the magnitude of those. So in this plot, you can see the blues and purples. That's a down-welling. It would be, I'll tell you, it's a whirlpool. It's the sucking motion of the water that's going towards the bed. And in this particular instant, it's taking up almost 25% of the channel. That's followed by these green areas that are somewhat still and possibly representative of up-welling or boils.
These turbulent structures are really in areas in the river, really cyclic in nature. You can watch the whirlpools form and get bigger and then dissipate. Then generally, somewhere around that area within just a matter of seconds, you'll get this huge upwelling or this big boil that arise through the surface and sometimes break the water surface by three feet. It's just really impressive.
The bottom plot is at same cross-section that now we're looking like you would typically look at velocity distribution of the water that's flowing in the downstream direction. So, we're used to seeing fastest flows at the surface here the middle of the channel. In this particular cross-section, we're looking at jets of water that are flowing somewhere in the magnitude of probably 15 feet per second at a depth of 100 feet. It's just that they're tunnels in the water column that they're working as jets. That's primarily due to to the irregular bed form that it's passing through but it's impressive.
This is another counterplot that you have to kind of switch gears in your mind because the ones we'd looked at previously had been from bank to bank, where we're going across the channel. In this particular instance, we sat at the center of the river and just drove straight down the middle of the river.
So in the US, we'd expect that if we were driving down the middle of the river to have a pretty uniform depth in three-depth transect. In this reach of the Congo, we start at a depth of around 100 feet on the left side. And then, as we go straight down the center of the depth, it gets shallower and shallower and we come up to a depth of only 20 feet.
Of course, that's the chimneys and rises and falls, so the water is going around in some areas. But you can see the effect of this shallow area of the river on the water behind it. The blues and purples are representative of stagnant flows so there's no water flowing pass it. It's like a natural dam.
Then it gets deep again. It's like a plunge pool but the really interesting part of this plot is in this area here, where you get this irregular bottom that's acting like a series of ramps. So you get the same quantity of water that's flowing from this deep area through the shallow water. So to get that same quantity, it has to accelerate to get over that narrow section. So it does act like a ramp. You'll see it. The reds and yellows are the acceleration and it gets deeper and it slows down. When it gets shallower, it accelerates.
If you look at the up component here where we're looking at upwellings and downwellings, you'll get exactly what you would expect. On the areas of the ramp, you get these blues and greens which where the water getting shot to the surface. And then, as soon as shoots to the surface, the bottom drops out from under it because it gets 50 feet deeper. So immediately behind that, you get the whirlpool effect where it's getting suck back down to the bottom to make up for that extra area that it's having to cover.
This is the 'turbulence'. This is in that same area. When I started playing, it's obviously not National Geographic footage. This is someone who has grabbed my camera and hit the record button because the river was so just incredible at this particular location. This footage, unfortunately, doesn't give it quite the same effect that if you're sitting on the boat yourself. But our voices are pretty loud here and you kind of hear me. I'm laughing but it's not laughing because I'm having fun. It's the same laugh your children have when they go to the haunted house and they don't know if they're supposed to scream or cry or what. That's what this sound is going to be.
[Start of Video]
Video Speaker 1: Woah! Get out of here.
John Shelton: That's the laugh. We looked behind the boat. That was about 30 feet in diameter.
Video Speaker 1: Oh, my! What?!!
Video Speaker 2: They fell . All right, you guys
Video Speaker 1: You got it?
John Shelton: Yeah.
Video Speaker 1: What did you see? Down-welling?
John Shelton: Down-welling at 100 feet, up-welling at 200 feet.
Video Speaker 2: Wow, it's really awesome.
John Shelton: Oh, God. It didn't look that shallow.
Video Speaker 1: How shallow?
John Shelton: It's 300 feet.
Video Speaker 1: Three hundred feet?
John Shelton: Yeah.
[End of Video Clip]
John Shelton: The rivers I'm used to, when you have that kind of surface turbulence, it's generally due to just the shallow nature of the stream where you get some kind of bed form directly below the surface that's causing that break. Obviously, I'm not used to this big river, but the fact that you we're getting that kind of turbulence at that 300 feet up, it was just amazing to me. It was the fun section.
There were a lot of times where our boat captain would be keeping man, too. It's a 25-horsepower motor. That I would be sitting taking notes or writing in my log and I hear the motor running and I'd look up and look at the bank and I'd write for another five or 10 minutes. And I'd look up and looked at the bank and I don't think we've moved. We're just going up as fast as the boat can, which in a lot of cases, was backwards.
Where we go from here? We collected an incredible amount of data on the river while we were there. The majority of that has been processed. We do still have some more out there, some different things. We're going to take a look at. We have been relating the hydraulic data that we were able to collect to the fish diversification data that was also collected.
Visualization projects – they did the… The Explorer episode's out and available. There's some animation still that we'd like to work on, some fact sheets. There was a hydrologist in Illinois who took the data and did some pretty incredible plots with it looking at contour depth and overlaying velocity and it explained a lot. I'll show you one example of that.
The water quality samples were processed. There are some questions on a lot of that data. The DRC government held on to those samples for well above the processing time, so there were some issues there.
And then future project, we're really hoping to get to go back. Melanie and her team have been back. I know they went last year. But there was a lot of interest in the data we were able to collect, especially the flow data. So we're really hoping to get another shot.
This is one of those products that hydrologists in Illinois was able to create. This is in the area of Bulu. That's where lethops was found. And if you look, you can see this area of brown. It's still relatively deep in the 60 to 80 meter range, but it's relatively flat. There's not a whole lot of change in that elevation. If you go just downstream into the curve, you can see where the changes in contour are pretty sharp. It's like a big plunge pool like you'd expect to see at the bottom of the waterfall here and it drops off to between 400 and 500 feet at that particular area.
This is exactly the same area where the fishermen are finding lethops. I don't have it in this particular slide but if you were to overlay velocity on top of this plot, there's actually a jet occurring in this area. There's a little circular right here where the water is shooting straight to the surface. So you get this really deep area, just like we were looking for with that one hydraulic structure, where they get in from the normal flows into the upwelling in that particular area and get shot to the surface. And then the fishermen are collecting them on the clips over here. So, we think we found the home.
And with that, I'll take any questions.
Audience 1: So any notion of the river being as dramatic as... collected and found. I mean, do the locals have a sense of its depth?
John Shelton: I don't think so. The locals were amazing. In the areas that we were, fishing is a primary supply. And they were getting in these pirogues that were maybe 18 inches wide and had maybe 18 inches deep and 10 feet long. And they'd stand up in them and paddle across the river. And it was amazing.
As far as depth, no. The models that we had didn't predict anywhere near the depth that we were seeing in some of these places. Even the velocity distributions that we will predict, we were measuring velocities in excess of eight meters a second in some spots, and particularly around Bulu. Well, in perspective, of all the states I've worked in in the US, I've never measured probably five meters a second. That's the fastest I have measured Stateside, I would imagine. It was substantially faster. So it was that. And we had no idea what to...
Ned had been at the trip previous and had taken a little locals fish finder with him but it didn't… I think it maxed out at 60 meters or something. He didn't have any idea we're going to find the depths that we did.
It was pretty constant. I mean, there were some areas in especially in the… A lot of it are hard rock, a lot of the places. There's not a whole lot of finds or anything that we're seeing suspended. What we actually do was approaching low flow. It was really dry season so there wasn't a whole lot of substantial run-off that we were seeing increases in turbidity. And most of our turbidity was straight line and stuff and we did an extremely well QA, but we didn't see a whole lot of change.
Most of the fish they were collecting, they were looking for smaller tributaries coming in the river. So they'd road panel, is that…? Yeah. They'd go in and I don't know what road panel is. It's poison.
Audience 2: More like the fish and they float to the surface.
John Shelton: Yeah, they float to the surface and then they'd net them up and... Yes?
Audience 3: ...
John Shelton: Yes, sir?
Audience 4: You said you learned that the dry season?
John Shelton: Yes.
Audience 4: And what's the condition flight during the wet season?
John Shelton: I would love to find out. We were there from I think it was the middle of June to the middle of July and the river was dropping the whole time we were there. I think it was 1.3 million when we started. It was down in the 900,000 range when we left.
But just looking at the banks, trying to estimate where during the half-low season the water might be, I'd guess probably almost twice where we measured, probably 2.5 million CFS. That's total speculation on my part. But I would love to measure it 2.5 million CFS. But it wouldn't be out of carved wooden pirogue.
Audience 5: What type of… What's in the river bottom, I couldn't understand, that's... amount of power in the river? There's a lot of pressure.
John Shelton: Well, that's where we – that's another thing. We really like to have had a geologist on the ground looking at the actual photograph that was there, but it's hard. It's hard and we're guessing it has to be relatively young. I mean, eventually it will weather. But compared to the bathymetry upstream, it's much, much younger than what the river has been running over historically.
There are several existing models and I'm not a modeler, so I'm really not qualified to answer that question. The particular modeler who had been working with the American Museum Natural History works in the Connecticut Water Science Center for the US Geological Survey. He had done a lot of the legwork and I owe this trip to him, actually. It was his suggestion that we get field folks on the ground to collect data and see how the comparison stands out. But I'm not sure how to create it.
That's big at teaching job, actually. It's working with the Mekong River folks and teaching them how to monitor the Mekong River and measure the Mekong River. We were in Iraq in 2006 and we installed the first two stream gauges and post-Saddam Iraq. Those gauges are real time and available on the Web. Actually, you had to go to Idaho Water Science Center webpage to find the Tigris River in Northern Iraq. But that was where the project originated but I was teaching project too. We actually installed those gauges with the class of Iraqi engineers to show them the principles of gauge construction and how it worked.
Audience 6: On a similar line, how much interest was there from the government of DRC or Republic of Congo on the work done and how much are engaged or how much information?
John Shelton: It depended on which department you talked to. I don't even know. There was some water management group somewhere that supposedly had continuous water level data on the river but they weren't sharing it with anybody. And they actually did contact me and rumor had it too that they actually had an ADCP but didn't know how to use it. So there was some interest there in getting some teaching.
There were some other nationals. They're working with the DRC who were incredibly interested in what we were doing and would very much like us to go back. But the politics are just crazy and that was interesting. So, we'll kind of see.
We have another proposal that's been floating around for quite awhile now. I think it might even be USAID. He's looking at bathymetry of the upper Congo, so from Kinshasa upstream. That, I think, a lot less desirable reach to be in but there's probably more chance of problems in some of those areas. The Lower Congo, the villages we were in were just fantastic. It was great time.
Audience 7: How did the natives explained the isolation of the species?
John Shelton: I don't know that they had an explanation. They just accepted it for what it was. They're called Lamprologus lethops, I don't remember what they called it, mandeli boro, I think which is 'white office'. And I'm not sure how they came up with that name. It was, just an anomaly to them. They were used to seeing it. They knew it wasn't real widespread but I don't think they had any theories on why they found it dead or why it was white. But they just want to get paid for it.
Thank you very much.