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

Samuel Bentley

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

Text

Landward ShorelineMigration1932-2010

Compare:

active

versus

inactive

delta regions

Twilley, R.R., Bentley, S.J., Chen, Q. et al. Sustain Sci(2016) 11: 711. https://doi.org/10.1007/s11625-016-0374-4

Landward ShorelineMigration1932-2010

Compare:

active

versus

inactive

delta regions

Twilley, R.R., Bentley, S.J., Chen, Q. et al. Sustain Sci(2016) 11: 711. https://doi.org/10.1007/s11625-016-0374-4

Landward ShorelineMigration1932-2010

Compare:

active

versus

inactive

delta regions

locations for graph in final slide

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)

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?

What are the implications?Land growth:

Population Growth

Land Loss:

Population Loss,

except where communities investTwilley, R.R., Bentley, S.J., Chen, Q. et al. Sustain Sci (2016) 11: 711. https://doi.org/10.1007/s11625-016-0374-4

What are the implications?Land growth:

Population Growth

Land Loss:

Population Loss,

except where communities investTwilley, R.R., Bentley, S.J., Chen, Q. et al. Sustain Sci (2016) 11: 711. https://doi.org/10.1007/s11625-016-0374-4

Torbjörn E. Törnqvist

A new subsidence map for coastal Louisiana

Nienhuis et al. (2017), GSA Today, doi:10.1130/GSATG337GW.1

Surface-elevation table – marker horizonmeasurements (shallow subsidence)

Global PositioningSystem

measurements(deep subsidence)

Satellite altimetrymeasurements

(sea level)

12 ± 8 mm/yr

Present-day rates of relative sea-level risein coastal Louisiana

Jankowski et al. (2017), Nature Communications,doi:10.1038/ncomms14792

A new subsidence map for coastal Louisianato be interpreted with caution!

Nienhuis et al. (2017), GSA Today, doi:10.1130/GSATG337GW.1

Mead Allison

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

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

SUBSIDENCE

SUPERSTATION

InSAR

REFLECTOR (?)

Holocene

Delta Strata

DETAILED

BOREHOLE

DESIGN

Myrtle Grove

SuperstationOptical Fiber Strainmeter/Extensometer:

Cathleen Jones

FUTURE OUTLOOK:

Remote Sensing of

Subsidence in Louisiana

Cathleen E. Jones

Radar Science & Engineering

Jet Propulsion Laboratory,

California Institute of Technology

Large-Scale Measurements of the Earth from Space: Radar Remote Sensing

Project site

Source: Jet Propulsion Laboratory (JPL)

INSAR: Interferometric Synthetic Aperture Radar

Airborne

NASA

UAVSAR

Photo Credit: NASA/AFRC

Measurements of subsidence in New Orleans and the Mississippi River delta

using radar interferometry (InSAR)

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, 3867-3887, doi:10.1002/2015JB012636.

Satellite Radar Imaging of the Mississippi River Delta

Today:

European Space Agency Sentinel 1a/b

• Free and open data policy

• ~65’ spatial resolution

Next: NASA-ISRO Synthetic Aperture Radar Mission (NISAR)

2021+: NASA NISAR Instrument

Movie Credit: Franz Meyer, U. Alaska / Fairbanks

Key NISAR characteristics that would

uniquely capture Earth in motion:

• Dense temporal and spatial sampling• Repeated INSAR images every 12 days

• Spatial resolution 20’-40’

• 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

NASA UAVSAR is a prototype for NISAR