Simard et al. (2025) Delta-X: An airborne remote sensing framework to calibrate hydrodynamic and ecogeomorphic processes responsible for land building in coastal deltas

Identification

• Journal: Remote Sensing of Environment
• Year: 2025
• Date: 2025-12-26
• Authors: Marc Simard, Cathleen E. Jones, Robert R. Twilley, Edward Castañeda-Moya, Sergio Fagherazzi, Cédric G. Fichot, Michael P. Lamb, Paola Passalacqua, Tamlin M. Pavelsky, David R. Thompson, Saoussen Belhadj-aissa, Pradipta Biswas, Alexandra Christensen, Luca Cortese, Michael Denbina, Carmine Donatelli, Sarah Flores, Andy Fontenot, Joshua P. Harringmeyer, Daniel Jensen, John Mallard, Justin A. Nghiem, Talib Oliver-Cabrera, Ali Reza Payandeh, André Rovai, Elena Solohin, Antoine Soloy, B. K. Varugu, Dongchen Wang, Kyle Wright, Xiaohe Zhang, Yang Zheng
• DOI: 10.1016/j.rse.2025.115201

Research Groups

• Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.
• Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA.
• Institute of Environment, Florida International University, Miami, FL, USA.
• Department of Earth and Environment, Boston University, Boston, MA, USA.
• Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
• Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, TX, USA.
• Department of Earth, Marine and Environmental Sciences, University of North Carolina, Chapel Hill, NC, USA.

Short Summary

This paper presents the Delta-X framework, an airborne remote sensing and in situ data integration strategy used to calibrate and validate hydrodynamic and ecogeomorphic models. The framework was implemented in the Mississippi River Delta to quantify the processes of mineral sediment deposition and organic matter production that determine deltaic land sustainability.

Objective

• To advance the understanding of the fundamental connections between coastal hydrology, ecology, and geomorphology that control deltaic soil accretion.
• To identify which parts of a delta can survive projected relative sea-level rise (RSLR) by quantifying mesoscale (~1 ha) patterns of land building.

Study Configuration

• Spatial Scale: Mesoscale (ecogeomorphic cells of ~1 ha) across the Atchafalaya (active) and Terrebonne (inactive) basins of the Mississippi River Delta, Louisiana, USA.
• Temporal Scale: High-frequency tidal cycles (hourly), seasonal cycles (spring high-discharge and fall low-discharge), and multi-decadal projections (to the year 2100).

Methodology and Data

• Models used: Delft3D FM (unstructured grid for hydrodynamics and morphodynamics), NUMAR (Numerical Understanding of Marsh Accretion Rates for ecogeomorphology), and ANUGA (preliminary testing).
• Data sources:
  • Airborne Remote Sensing: AirSWOT (Ka-band interferometric radar for water surface elevation/slope), UAVSAR (L-band repeat-pass InSAR for wetland water level change), and AVIRIS-NG (imaging spectrometer for suspended sediment, vegetation type, and biomass).
  • In Situ Data: Water level gauges (TPTs), Acoustic Doppler Current Profilers (ADCP), total suspended solids (TSS) samples, soil cores (137Cs dating), and feldspar marker horizons for accretion rates.
  • Satellite/Ancillary: Sentinel-2 (vegetation mapping), NAIP (land/water classification), and USGS/NOAA topobathymetric data.

Main Results

• Instrument Performance: AirSWOT achieved a water surface elevation accuracy of 12 cm RMSE and slope accuracy <1 cm/km; UAVSAR resolved water level changes in wetlands with 3 cm RMSE.
• Model Calibration: Integrating AirSWOT data reduced the hydrodynamic model's water level RMSE from 18 cm to 9 cm in spring and from 14 cm to 10 cm in fall.
• Morphodynamic Validation: The coupled model showed an R² of 0.61 for inorganic mass accretion rates when compared to Coastwide Reference Monitoring System (CRMS) stations.
• Ecogeomorphic Findings: Calibrated Chézy friction coefficients for vegetation ranged from 30 m½/s (forest) to 57 m½/s (aquatic vegetation), significantly impacting tidal propagation and sediment retention.
• Sediment Transport: Settling velocities were calibrated to 0.1 mm/s with critical shear stresses for erosion at 0.5 Pa and deposition at 0.1 Pa.

Contributions

• Establishes the first comprehensive framework to integrate rapid-repeat airborne InSAR with imaging spectroscopy to resolve high-frequency tidal processes and spatial heterogeneity in deltas.
• Provides a scalable methodology to calibrate mesoscale models using "ecogeomorphic cells," bridging the gap between point-based in situ measurements and coarse satellite observations.
• Demonstrates the relative importance of channel network density versus organic productivity in maintaining deltaic elevation.

Funding

• NASA Earth Venture Suborbital-3 (EVS-3) Program (reference code: NNH17ZDA001N-EVS3).
• NASA FINESST grants (80NSSC20K1645, 80NSSC20K1648, 80NSSC21K1612).
• Support from the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA (80NM0018D0004).

Citation

@article{Simard2025DeltaX,
  author = {Simard, Marc and Jones, Cathleen E. and Twilley, Robert R. and Castañeda-Moya, Edward and Fagherazzi, Sergio and Fichot, Cédric G. and Lamb, Michael P. and Passalacqua, Paola and Pavelsky, Tamlin M. and Thompson, David R. and Belhadj-aissa, Saoussen and Biswas, Pradipta and Christensen, Alexandra and Cortese, Luca and Denbina, Michael and Donatelli, Carmine and Flores, Sarah and Fontenot, Andy and Harringmeyer, Joshua P. and Jensen, Daniel and Mallard, John and Nghiem, Justin A. and Oliver-Cabrera, Talib and Payandeh, Ali Reza and Rovai, André and Solohin, Elena and Soloy, Antoine and Varugu, B. K. and Wang, Dongchen and Wright, Kyle and Zhang, Xiaohe and Zheng, Yang},
  title = {Delta-X: An airborne remote sensing framework to calibrate hydrodynamic and ecogeomorphic processes responsible for land building in coastal deltas},
  journal = {Remote Sensing of Environment},
  year = {2025},
  doi = {10.1016/j.rse.2025.115201},
  url = {https://doi.org/10.1016/j.rse.2025.115201}
}

Generated by BiblioAssistant using gemini-3-flash-preview (Google API)