presentationPPT_Falcini

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Orléans, 6 juillet 2011 Hôtel de Région Centre

5ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents:

5 ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents Orléans 6 juillet 2011 Hôtel de Région Centre Federico FALCINI Monitoring Mississippi Delta Flood from SPACE Postdoctoral investigator in the Department of Earth and Environmental Science - University of Pennsylvania. I am a physicist with a PhD in Earth Science that has been trained in Geophysical Fluid Dynamic, Physical Oceanography and Sediment Transport. I have been working on Coastal Geomorphology and Delta Morphodynamics since 2008, when I came in US from Italy.

5ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents:

5 ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents Orléans 6 juillet 2011 Hôtel de Région Centre You are using satellite data in your research on Mississippi Delta. From satellite to the Delta is great distance, yet you manage to deduce relevant information from satellite data. Could you tell us more? Hiring satellite data is becoming quite necessary for several kind of investigations related to the sea surface. In our research on the Mississippi Delta we mainly used sea surface temperature (SST) data recorded by the A dvanced V ery H igh R esolution R adiometer (AVHRR), a sensor operating onboard of the  NOAA - POES series ( P olar- O rbiting Operational E nvironmental S atellites). These satellites have a polar orbit over the Earth at an approximate altitude of 830 km . The AVHRR sensor is a radiation-detection imager that can be used for remotely determining the surface temperature of a body of water. This scanning radiometer uses 6 detectors that collect different bands of radiation wavelengths with a resolution all of 1.1 km. Along track wavelengths data have to be processed and interpolated in order to obtain SST high resolution maps. For our work we used maps provided by the Earth Scan Laboratory of the Louisiana State University (http://www.esl.lsu.edu/home/). This Laboratory has indeed developed techniques for quantifying surface sediments, temperature, and chlorophyll , developing also novel ways of "de-clouding" temperature imagery in order to map temperatures in the Gulf of Mexico and track ocean features even during summer. As you can see form the image below (Fig. 1) SST resolution is high enough to recognize the Mississippi River (MR) plume from the temperature contrast between the sea water and the fresh, cold river water. Moreover, SST maps are able to characterize the spatial pattern of such a plume, allowing us to set some hypothesis about the difference between the MR plume and the other river plumes in the Louisiana coast, such as the Atchafalaya River. Fig. 1. NOAA/AVHRR image of sea surface temperature from the high discharge event of June, 2011. On to the left, the Atchafalaya spreading plume and, on to the right\ the Mississippi River plume. One can note that river waters are colder than the sea surface water and that the cold filament outflowing from the Southwest Pass of the Mississippi birdsfoot shows no spreading. Data were processed by the Earth Scan Lab (Coastal Studies Institute, Louisiana State University).

5ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents:

5 ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents Orléans 6 juillet 2011 Hôtel de Région Centre What are you trying to show or demonstrate? What are the main research questions you are working on [using satellite data]? The main goal of our theory is to provide mathematical and physical evidences regarding the “non-efficiency” of particular river plumes (such as the MR plume) in building a mouth bar (see Fig. 2). Prograding deltas are formed by the deposition of sediment by the river at its mouth. Deposition can occur at the channel lateral margins, as sub-aqueous levees, and at the center of the channel, as a mouth bar. Stronger levee deposition aids in the formation of elongate channels, while stronger vertical aggradation of a mouth bar yields bifurcating channels and thus branching network systems. The latter has been recognized as an ideal pattern for delta restoration. It is clear that understanding the relations between river mouth morphology and outflow hydrodynamics is critical for designing effective delta restoration schemes. Our mathematical theory (i.e., a novel Potential Vorticity theory) provides some insights about how narrow, filament-like, river plumes may not give rise to branching network formation. These kind of plume, characterized by an high Potential Vorticity, are indeed associated to elongate channels, such as the Southwest Pass of the Mississippi Delta. SST images, being able to show spatial pattern of river plumes, proved the relation between river mouth morphology and outflow characteristics, and allowed the comparison beween different kind of plumes. Fig. 2. The lower Mississippi Delta and Louisiana coast, with the details of (a) Wax Lake Delta of the Atchafalaya River and (b) Southwest Pass of the Mississippi birdsfoot. Google Earth imagery ©Google Inc.

5ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents:

5 ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents Orléans 6 juillet 2011 Hôtel de Région Centre What lessons did you learn from Hurricane Katrina for your research? What we know from several studies that have been published in the last decade is that with increasing rates of sea level rise, human-accelerated land subsidence and large-scale alteration of water and sediment supply, many of the world's heavily populated river deltas are threatened with irreversible land loss. This problem is acute on the Mississippi Delta, where scientists are proposing artificial diversions that would harness natural land-building processes in order to mitigate wetland loss in the vicinity of New Orleans. Most of New Orleans is below sea level, and South Louisiana’s coastal wetlands, which once helped buffer the city from giant storms, have been disappearing at a spectacularly swift pace. There is a consensus that protecting and expanding coastal marshes is vital for coastal Louisiana, however there is much less agreement regarding how to do so. Plans to create diversions in the lower Mississippi channel in order to build new wetlands from River sediment are gaining traction, however a scientific understanding of marsh-building is urgently needed. There is currently much debate regarding how, and to what degree, sediment from the Mississippi and Atchafalaya Rivers contributes to maintaining and building fragile coastal marshes. Some have argued that large hurricanes may play an important and even dominant role in keeping Louisiana’s coastal marshes above sea level; however, others have countered that the ultimate source of sediment is the river itself.

5ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents:

5 ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents Orléans 6 juillet 2011 Hôtel de Région Centre How would you describe the impact of floods, particularly concerning sediments, on coastal wetlands? The recent flood that inundated the Mississippi Delta was arguably the largest in history. Although such a large flood may be catastrophic to humans, sediment carried to sea by the swollen river has the potential to combat wetland loss in some areas. In this regard, this historic flood presented a rare and time-sensitive opportunity to determine the impact of a geologically-significant flood event on coastal sedimentation. Colleagues from the Mississippi Mineral Resources Institute, USGS, University of Pennsylvania and I are indeed studying the Mississippi and Atchafalaya River plumes ( http://www.nature.com/news/2011/110615/full/474259a.html ). The Mississippi emits a focused jet of water and sediment that penetrates a significant distance into the ocean with only limited mixing (Fig. 3). The intentionally-flooded Atchafalaya basin, on the other hand, is currently emitting a wide and diffuse plume at its outlet that appears to be trapped in coastal waters. To characterize if and how sediments from this historic flood contribute to deposition and maintenance of Mississippi Delta coastal marshes is of fundamental importance. This allows determination of flood-induced deposition rates and also sediment provenance. Results from such an investigation will be of great practical use for managing future floods and diversions in order to maximize wetland sedimentation, to combat pervasive inundation and erosion in the face of relative sea level rise. Fig. 3. Lower Mississippi Delta - MODIS image (Institute of Marine Remote Sensing, USF) of June 1st, 2011.

5ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents:

5 ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents Orléans 6 juillet 2011 Hôtel de Région Centre The stakeholders from the Loire river basin identified vulnerabilities (to floods or erosion for example), that they try to reduce supported by research results. At the scale of the river basin or at the scale of some territories like the estuary, what benefits do you see in the use of satellite data for a better understanding and knowledge of ?natural? phenomena? Beyond what I have said about the use of SST data for river plume investigation, one has to stress the incredible development regarding data from Moderate Resolution Imaging Spectroradiometer (MODIS), a key instrument aboard the Terra and Aqua satellites. These data improved our understanding of global dynamics and processes occurring on the land and in the oceans. More specifically, the measured ocean parameters are chlorophyll content, organic and mineral content, SST, and sea ice cover. In the last few years several methods and application from MODIS data have been described in order to improve the remote sensing of river characteristic in terms of suspended sediment concentration, both offshore and upsteram. In our MR flood investigation ( http://www.nature.com/news/2011/110615/full/474259a.html ) we hired MODIS images elaborated by the Institute of Marine Remote Sensing of the University of South Florida ( http://imars.marine.usf.edu/ ). By using near real-time MODIS images (Fig. 3) provided by such an Institute, it has been possible to keep track of suspended sediment of the Mississippi river plume during the flood. This allowed us to direct oceanographic surveys in real time , and thus to sample the plume velocity, suspended sediment, and hydrologic features.

5ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents:

5 ème Rendez-vous annuel entre la communauté scientifique et les gestionnaires du bassin de la Loire et de ses affluents Orléans 6 juillet 2011 Hôtel de Région Centre In connection with these questions of observation and satellite data, what changes in your research could you expect with the shift towards open data (state or regional data)? What benefits would you see for your work for the coming years? All the data I have been using are available from the principal US and European space agencies. Moreover, several laboratories, both in Europe and US, provide near-real time satellite maps at different spatial scales. However, since these images are the result of complex techniques that involve interpolations and algorithms to obtain oceanographic parameters from wavelengths, the cooperation with specialized researcher, laboratories and institution is crucial. Any user should have the control and/or the knowledge of what is behind a specific satellite image. You deal with subjects certainly visual, but also very technical. How do you make your work accessible to managers and developers? The “technical” part of any oceanographic or hydrologic research on river management and coastal geomorphology is usually the mathematical framework that described the phenomena. The use of this kind of research therefore requires that managers and developers should have a basic scientific education that allows for a useful discussion and communication with the researchers. However, I do believe that a scientific research should be able to provide a sort of “bulk” results (i.e., formulations or parameterizations) that may represent the bridge between a theoretical work and what the society asks from science.