December 2017 - After 2 years of absence I decided to go back to the AGU Fall Meeting. And as the Conference Center in San Francisco is renovating, this year the meeting was held in New Orleans. An excellent opportunity for me to visit the mighty Mississippi River and Delta. In advance of the AGU Fall Meeting, I travelled with my colleagues (Sanja,
Jasper and
Lisanne) along the Mississippi River. The Mississippi is well studied and you can find a lot of talks/ posters about this system at AGU as well, so lets see for ourself.
Day 1 (Utrecht - Baton Rouge)
The first day would be a long day of travelling from our hometown Utrecht all the way to Baton Rouge. The first stop was Schiphol Airport (Amsterdam), with a transfer in Atlanta we arrived at 5pm local time in New Orleans. From there we hired a car and drove to our first stop Baton Rouge, where we had a good night rest.
Day 2 (Baton Rouge - Vicksburg)
Our first stop of the day was at the Center for River Studies. Here, they built this new facility to inform the public about the challenges of the Lower Mississippi River and Delta.
Clint Wilson showed us this new facility with the information center showing some cool maps of land loss, former delta lobes and a descriptive geological cross-section of the delta. Interesting was to see the map with measures that are implemented or going to be implemented in the Lower Mississippi Delta to reduce land loss and flood risk.
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| Geological cross-section Mississippi Delta |
The main reason for visiting this facility was because of their new flume, which is a distorted model of the Mississippi Delta on a scale of 1:6000. The scale model is used for both education and research. For example, they can test the effect of proposed measures on water levels, I am really interested in the results of the proposed sediment diversion to counteract land loss, and wonder what the bifurcation angle would be at the diversions.
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| In front of the model with Clint Wilson (in the middle). |
The scale model is very impressive. The initial bathymetry and elevation model was created by carving into a very dense foam. Sediment was added to the river bed, except for the parts where it is protected from erosion by human engineering. The density of the sediment used is much lower than natural sand (1.05) and to compensate for the lighter density, they chose a grainsize a factor 3 larger than in the natural river. Because they have a distorted model, they could scale the time of 1 hour experimental time back to an actual time of change. The initial elevation model and bathymetry is complete white, which allows for 20 projectors above the scale model to project informative maps on top of the scale model, such as a population density map or previous results.
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| Scale model of the Lower Mississippi River and Delta. |
After the visit of the Center of River Studies we went to Vicksburg following the Mississippi River for our next visit. Meanwhile, we visited the
Old River Control Structure, which controls the water and sediment distribution between the Mississippi and the Atchafalaya River. We also passed the
Morganza spillway, which is used to divert water from the Mississippi river to the Atchafalaya Basin when water levels are too high and create risk for flooding.
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| Information of the formation and role of the Old River Structure |
Day 3 (Vicksburg - Hammond)
On the third day of our trip we were visiting the US Army Engineers Research and Development centre and specifically the Coastal and Hydraulics laboratory. Here, we met with our host Keith Flowers and we wish to thank him again for having us. We started the day with a presentation of our work in Utrecht by myself and
Jasper Leuven, including the former river meandering experiments in the Eurotank and the ongoing estuary experiments in the Metronome. We had some really nice discussions about our approach, which could be seen as an effort to fill the gap between two types of experimental approaches, namely an analogue model and a distorted model.
After a short break, our host had setup a nice programm of a few talks followed by a visit in their lab.
First, David Abraham talked about the use of
high resolution bathymetry data for measuring bed-load transport, Second,
Gary Brown showed some results of sediment transport topics specifically about modelling sediment transport using
Adaptive Hydraulics (AdH). The last talk was by Jim Lewis who showed an analysis of the Mississippi river and tributaries future
flood conditions. This last talk realized how small the Rhine river is compared to the mighty Mississippi.
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| Ship simulator demonstration |
In the afternoon we had a tour to the facilities of US-ERDC. The first stop was at the
Ship Simulator, which is quiet impressive. Keith Martin explained how this simulator is used in finding optimal solutions for human engineering in rivers and harbors while the channel remains navigatible. Therefore, they implement possible management and interference strategies, calculate the resulting hydrodynamic conditions and subsequently let pilots experience the effects of the measures on navigation. Besides rivers, they also can simulate conditions at harbors for example Dutch Harbor well known from Deadliest Catch. Afterwards, Thar Pratt showed us some nice equipment that they use to collect field data.
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| ADCP, bathymetry and Lidar equipment on a model boat that can go under bridges. |
The final stop of the day, before we headed back in the direction of New Orleans, was the Froude scale model of the Santa Ana River.
Jeremy Sharp investigates what the effect of bridge pillar design is on the scour around it. Because the Santa Ana river is facing more extreme discharges, future scour was anticipated to become more extreme as well, posing risks for the stability of the bridge. Together with stakeholders, they optimised the design of the pillars to minimise scouring by a suprisingly 30%. Outside this building, they had a 1:1 model to study how
levee breaches can temporarily be fixed with flexible solutions: in this case a sort of balloon filled with 70% water and 30% air.
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| The new bridge pillars tested in a Froude scale model |
Overall, it was a very nice day with interesting talks, fantastic facilities and we met some nice people. Before we left, David Abraham showed this absolute fantastic poster of the
Friedkin experiments of 1945, which was the basis for my PhD work on
experimental meandering rivers.
Day 4 (Hammond - Morgan City)
Stops:
Mandalay refuge for a short walk on the Nature Trail
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| Impression photos of our 4th day. |
Day 5 (Morgan City - Lake Charles)
Stops:
Morton Salt
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| Impression photos of our 5th day. |
Day 6 (Lake Charles - Gonzales)
Cancelled swamp tour because of snow and cold weather,
Oak Alley Plantation closed because of closed roads. After a short stop at the
Atchafalaya Basin we continued to our journey towards the hotel, which had a power outage so that we had to wait a couple of hours before check in.
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| Impression photos of our 6th day. |
Day 7 (Gonzales - New Orleans)
We ended our excursion today with a flight over the
Mississippi delta. From the New Orleans Lakefront Airport we flew to the mouth of the Mississippi river and then to the area around Grand Isle. From there we returned over the swamps to New Orleans. At the end we had some scenic sights on the skyline and upstream Mississippi. You can get an impression from the photos I took below.
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| Impression photos of our 6th day. |
Day 8 ( New Orleans)
Sunday off, lets go sightseeing in
New Orleans!
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| Impression photos of New Orleans. |
Day 9 - 13 (AGU Fall Meeting)
After visiting the Mississippi River and Delta as well as New Orleans, the AGU Fall Meeting started. On the first day, I presented some work from Durham about a transfer-function noise model that I used to study spatial variation in stresses and its parameters. We are interested in how the geomorphic setting fits with the variation in the parameters, and if the geomorphic setting could be used as a first-order estimate of how the groundwater level will respond to stresses.
My second presentation was about the effect of shoal margin collapses on the channel-shoal morphodynamics of an estuary. I have been done some Delft3D modelling within I included a paramaterization for the occurrence of collapses and found that by including the collapses channels become shallower and more small channels develop on the tidal flats (also known as shoals or tidal bars).
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| Impression photos of the conference center and our poster. |
Day 14 (Gilbert Club)
After the AGU Fall Meeting there is this tradition of the
Gilbert Club, which is organized by Bill Dietrich of University of California, Berkeley. As the fall meeting was not in San Francisco, Nicole Gasparini of Tulane University organised the meeting this time.
As always we started late and with an introduction of all attendee. On the schedule there were 3 keynotes and some short presentations by the Program Director (Justin Lawrence) of the National Science Foundation as well as the Editor (John Buffington) of JGR-Earth Surface.
The three keynotes were given by:
Jane Willenbring - Linking life, landscapes, and the legacy of transience.
Greg Tucker - How do we test landscape evolution theory? An example of multi-model assessment using a case study in post-glacial drainage network incision.
Astrid Blom - The alluvial river profile: its concavity, surface texture, and channel-forming discharge.
The program ended with some short pop-up of 2 minutes max per person.
After the talk of Astrid Blom, we met Kyle Straub to have a look at his lab facility. Here, they study the development of deltas and specifically they look at the stratigraphy and the process of compensational filling of the basin. It was really nice to see this analogue model of a delta on a continental shelf.
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| Top-view of a delta experiment from Kyle Straub (Tulane University) |
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| Cross-section showing the distribution of channel (gray) and overbank (white) deposits. |
Day 15-17 (New Orleans - Utrecht)
Louisiana Tour Company - Swamp Tour
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| Impression photos of the swamp tour including alligators. |
After the swamp tour we arrived at the airport with the news that due to a power outage in Atlanta we had to stay another night in New Orleans.
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