Neuhauser et al. (2026) Seasonal hazard-vulnerability patterns between drought and wildfire in New Caledonia derived from remote sensing products

Identification

• Journal: International Journal of Applied Earth Observation and Geoinformation
• Year: 2026
• Date: 2026-02-01
• Authors: Mathis Neuhauser, Alexandre Peltier, Thomas Ibanez, Marc Despinoy, Michel Le Page
• DOI: 10.1016/j.jag.2026.105159

Research Groups

• ESPACE-DEV, University of New Caledonia, University of Montpellier, University of Antilles, University of Guyane, University of Réunion, IRD, Nouméa, New Caledonia, France
• METEO-FRANCE, Nouméa, New Caledonia, France
• AMAP, University of Montpellier, CIRAD, CNRS, INRAE, IRD, Nouméa, New Caledonia, France
• CESBIO, University of Toulouse, CNES/CNRS/INRAE/IRD/UPS, Toulouse, France

Short Summary

This study analyzed seasonal and directional temporal relationships between vegetation drought and wildfire activity in New Caledonia using remote sensing and in-situ data from 2000-2024, revealing distinct seasonal patterns where vegetation stress precedes fires in the early dry season, and fires are followed by altered vegetation conditions later.

Objective

• To analyze the seasonal and directional temporal relationships between vegetation drought and wildfire activity in New Caledonia, specifically investigating the influence of vegetation condition on fire hazard and post-fire feedback effects on vegetation drought across different seasons and regions.

Study Configuration

• Spatial Scale: New Caledonia archipelago (Grande-Terre, Belep Islands, Loyalty Islands, Ile des Pins), aggregated at the municipal level (33 municipalities).
• Temporal Scale: 2000–2024 (25 years), with data aggregated at monthly resolution. Specific analyses covered 2000–2021 for drought-only and 2012–2024 for VIIRS-based fire products.

Methodology and Data

• Models used: Lagged Pearson correlation analysis, Seasonal correlation analysis, Directional interaction analysis (using a signed cyclic lag Δm), Kernel Density Estimation (KDE).
• Data sources:
  • Meteorological drought: 3-month Standardized Precipitation Index (SPI-3) derived from daily precipitation records from 52 in-situ weather stations (Meteo-France New Caledonia, 1950–present).
  • Vegetation surface conditions:
    • MODIS (since 2000): Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Normalized Difference Water Index (NDWI), Land Surface Temperature (LST).
    • ASCAT (since 2007): Soil Water Index (SWI).
    • Derived indices: Vegetation Condition Index (VCI), Temperature Condition Index (TCI), Vegetation Health Index (VHI = αVCI + (1 −α)TCI), Vegetation Anomaly Index (VAI), Temperature Anomaly Index (TAI), Moisture Anomaly Index (MAI). The Vegetation Health Index (VHI) derived from NDWI and LST was primarily used for drought-fire interactions.
  • Wildfire activity: Burned areas Anomaly Index (BAI) derived from daily burned-area detections (thermal anomalies/hotspots) from MODIS (since 2000) and VIIRS (since 2012) (NASA/FIRMS service), spatially aggregated by the Environment Observatory in New Caledonia (OEIL).

Main Results

• Robust and spatially coherent correlations were found between vegetation drought (VHI) and burned area extent (BAI) across New Caledonia.
• Meteorological drought (SPI-3) showed strong correlations with surface drought indicators (VHI, MAI) on the west coast (savannas, dry forests, farmland), but weaker correlations on the north-eastern coast (rainforest).
• Temporal lags in drought propagation varied: VHI was often synchronous with SPI-3 on the west coast, while a 1-month lag was observed on the east coast and some islands, indicating vegetation stress and soil moisture deficit detected 1 to 2 months after meteorological drought.
• Seasonal drought patterns were strong on the west coast during the dry (September–December) and intermediate (January–May) seasons, but less structured on the east coast.
• Drought-fire interaction patterns revealed distinct seasonal regimes:
  • During the early dry season (August–September), vegetation stress (VHI) consistently preceded fire activity (BAI), indicating a fire hazard configuration.
  • During the late dry season (November–May), fire occurrence (BAI) was followed by modified surface conditions (VHI), reflecting post-fire ecosystem vulnerability and feedback mechanisms.
  • An inverse pattern was observed in the intermediate season (February–March VHI preceding May–July BAI), suggesting that high vegetation health during the wet season can increase later fire risk due to fuel accumulation.
• Significant geographic contrasts emerged, with highly seasonal and lagged fire/drought relationships on the east coast, versus more synchronous and less season-dependent relationships on the west coast, likely influenced by agricultural practices and land management.
• A key temporal shift in interaction direction occurred around October, transitioning from vegetation condition driving fire activity (hazard) to fire events dominating and impacting vegetation (vulnerability).

Contributions

• Provides the first regional-scale characterization of seasonal and directional temporal relationships between vegetation drought and wildfire activity in New Caledonia.
• Quantifies the temporal sequencing of interactions, distinguishing periods of fire hazard (vegetation stress preceding fire) from post-fire vulnerability and feedback effects (fire followed by altered vegetation).
• Highlights the effectiveness of VHI (combining NDWI and LST) as a reliable wildfire risk indicator in New Caledonia, especially in regions characterized by seasonal water limitation and open-canopy vegetation.
• Offers actionable, region-specific insights for seasonally targeted and spatially explicit wildfire risk management in New Caledonia.
• Demonstrates the value of remote sensing for quantifying both fire hazard and vulnerability from a single vegetation indicator.

Funding

• Space Climate Observatory (SCO)
• French Pacific Fund (“Fonds Pacifique”)
• French National Research Institute for Sustainable Development (IRD)
• INSIGHT SAS

Citation

@article{Neuhauser2026Seasonal,
  author = {Neuhauser, Mathis and Peltier, Alexandre and Ibanez, Thomas and Despinoy, Marc and Page, Michel Le},
  title = {Seasonal hazard-vulnerability patterns between drought and wildfire in New Caledonia derived from remote sensing products},
  journal = {International Journal of Applied Earth Observation and Geoinformation},
  year = {2026},
  doi = {10.1016/j.jag.2026.105159},
  url = {https://doi.org/10.1016/j.jag.2026.105159}
}