Canary in the Coal Mine: Subsidence in Coastal Louisiana Press Conference

Transcription

1 Canary in the Coal Mine: Subsidence in Coastal Louisiana Press Conference Samuel Bentley, LSU Department of Geology & Geophysics professor and Billy and Ann Harrison chair in sedimentary geology Mead Allison, Tulane University Department of River-Coastal Science and Engineering professor and chair and The Water Institute of the Gulf director of physical processes & sediment systems Torbjörn E. Törnqvist, Tulane University Department of Earth and Environmental Sciences Vokes Geology professor Cathleen E. Jones, NASA Jet Propulsion Laboratory/California Institute of Technology radar scientist

2 Samuel Bentley

3 Enormous Modern Changes in Coastal Land Area of Mississippi River Delta (Projections: State of Louisiana) Text

4 Landward Shoreline Migration Compare: active versus inactive delta regions Twilley, R.R., Bentley, S.J., Chen, Q. et al. Sustain Sci (2016) 11:

5 Landward Shoreline Migration Compare: active versus inactive delta regions Twilley, R.R., Bentley, S.J., Chen, Q. et al. Sustain Sci (2016) 11:

6 Landward Shoreline Migration Compare: active versus inactive delta regions locations for graph in final slide

7 What Drives Land Loss or Gain in a River Delta? Sediment Supply: mud and sand from the river Sediment Retention: how much sediment is retained in the delta Global Sea Level Rise/Fall: inundates or exposes land Ecosystem Productivity (plant growth): adds soil volume, binds soil Subsidence: settling or sinking of land surface due to subsurface movement of earth materials (USGS)

8 What Drives Subsidence in a River Delta? a.sediment compaction b.glacial Isostatic Adjustment c.regional Sediment Loading d.faulting e.salt Dynamics f. Subsurface fluid withdrawal g.realignment of natural drainages (decomposition and oxidation of organic material) At what temporal and spatial scales do these processes act?

9 What are the implications? Land growth: Population Growth Land Loss: Population Loss, except where communities invest Twilley, R.R., Bentley, S.J., Chen, Q. et al. Sustain Sci (2016) 11:

10 What are the implications? Land growth: Population Growth Land Loss: Population Loss, except where communities invest Twilley, R.R., Bentley, S.J., Chen, Q. et al. Sustain Sci (2016) 11:

11 Torbjörn E. Törnqvist

12 A new subsidence map for coastal Louisiana Nienhuis et al. (2017), GSA Today, doi: /gsatg337gw.1

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14 Surface-elevation table marker horizon measurements (shallow subsidence) Global Positioning System measurements (deep subsidence) Satellite altimetry measurements (sea level)

15 Present-day rates of relative sea-level rise in coastal Louisiana Jankowski et al. (2017), Nature Communications, doi: /ncomms ± 8 mm/yr

16 A new subsidence map for coastal Louisiana to be interpreted with caution! Nienhuis et al. (2017), GSA Today, doi: /gsatg337gw.1

17 Mead Allison

18 DEVELOPING SUBSIDENCE SUPERSTATIONS IN THE MISSISSIPPI DELTA Mead Allison Torbjörn Törnqvist Jonathan Bridgeman Tim Dixon Barbara Kleiss Eric Marx Scott Nooner James Normandeau Michael Steckler Brendan Yuill Mark Zumberge

19 SUPERSTATION OBJECTIVES A. Test various measurement methodologies at a single site for: Intercomparison (temporal/magnitude sensitivity, bias, etc.) Referencing airborne/satellite SAR data Develop a relatively low-cost strategy to monitor a large region (delta) B. Measure subsidence rates over different depth intervals to: Extract information about deep vs. shallow (compactional) drivers Provide calibration/validation data for multi-parameter models

20 SUBSIDENCE SUPERSTATION

21 InSAR REFLECTOR (?) Holocene Delta Strata

22 DETAILED BOREHOLE DESIGN Myrtle Grove Superstation Optical Fiber Strainmeter/Extensometer:

23 Cathleen Jones

24 FUTURE OUTLOOK: Remote Sensing of Subsidence in Louisiana Cathleen E. Jones Radar Science & Engineering Jet Propulsion Laboratory, California Institute of Technology

25 Large-Scale Measurements of the Earth from Space: Radar Remote Sensing INSAR: Interferometric Synthetic Aperture Radar Project site Source: Jet Propulsion Laboratory (JPL)

26 Measurements of subsidence in New Orleans and the Mississippi River delta using radar interferometry (InSAR) Airborne NASA UAVSAR Photo Credit: NASA/AFRC Jones, C. E., An, K., Blom, R. G., Kent, J. D., Ivins, E. R., Bekaert, D. (2016). Anthropogenic and geologic influences on subsidence in the vicinity of New Orleans, Louisiana, J. Geophysical Res.-Solid Earth, 121, , doi: /2015jb

27 Satellite Radar Imaging of the Mississippi River Delta Today: European Space Agency Sentinel 1a/b Free and open data policy ~65 spatial resolution

28 Next: NASA-ISRO Synthetic Aperture Radar Mission (NISAR) Key NISAR characteristics that would uniquely capture Earth in motion: Dense temporal and spatial sampling Repeated INSAR images every 12 days Spatial resolution Comprehensive global measurements All U.S. land, almost all land globally & extensive areas around both poles Targeted new science observations Cryosphere, Ecosystems, Solid Earth, & wide variety of applications for societal benefit Free and open data policy 2021+: NASA NISAR Instrument Movie Credit: Franz Meyer, U. Alaska / Fairbanks NASA UAVSAR is a prototype for NISAR