Ha et al. (2026) Climate and soil moisture variability and cropland exposure in Western Yemen: a spatiotemporal analysis using satellite and reanalysis time series from 2000 to 2024

Identification

• Journal: Natural Hazards
• Year: 2026
• Date: 2026-02-18
• Authors: Tuyen Ha, A Govind, Nguyen Quang Thi
• DOI: 10.1007/s11069-025-07828-6

Research Groups

• Faculty of Resources Management, Thai Nguyen University of Agriculture and Forestry, Thai Nguyen City, Thai Nguyen Province, Vietnam
• GeoAgro Team, International Centre for Agriculture Research in Dry Areas (ICARDA), Cairo, Egypt

Short Summary

This study conducted a detailed spatiotemporal analysis of climate and soil moisture anomalies and associated cropland exposure in western Yemen from 2000 to 2024 using satellite and reanalysis data. It revealed a significant transition towards warmer and drier conditions, with declining precipitation and soil moisture, and a cumulative temperature rise of approximately 1.5 °C, leading to increased cropland vulnerability.

Objective

• To present a detailed analysis of spatial and temporal climate and soil moisture variability, assessing its seasonal trends in western Yemen.
• To examine the response of crop vegetation to climate and soil moisture variability during summer and winter crop periods in the study region.
• To estimate the spatial extent of croplands exposed to climate and soil moisture stress.

Study Configuration

• Spatial Scale: Western Yemen, with all datasets harmonised to a 1 km spatial resolution.
• Temporal Scale: 2000 to 2024, using monthly time series.

Methodology and Data

• Models used: Mann-Kendall (MK) test, Sen’s slope estimator, Spearman correlation analysis, Savitzky–Golay filter, ECMWF land surface model (within ERA5-Land).
• Data sources:
  • Satellite: Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) from MODIS/061/MOD13A2 (Terra) and MODIS/061/MYD13A2 (Aqua) 16-day composite products (1 km resolution).
  • Reanalysis: ERA5-Land for air temperature at 2 m height (°C), precipitation (mm), and 7–28 cm soil moisture layer (m³/m³) (hourly at 9 km resolution, aggregated to monthly and resampled to 1 km).
  • Ancillary: Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) (90 m resolution, resampled to 1 km), European Space Agency (ESA) Climate Change Initiative (CCI) annual land cover product (300 m resolution, reclassified and resampled to 1 km).

Main Results

• Western Yemen experienced a significant transition toward warmer and drier conditions from 2000 to 2024.
• Seasonal trend analysis indicated a significant decline in precipitation and soil moisture in summer, autumn, and winter.
  • Precipitation declined by approximately 1 mm per year in summer, affecting nearly 30% of the study area.
  • Soil moisture showed the largest decline in autumn and winter, affecting nearly 32% of the study area.
  • Multiple years (e.g., 2008–2009, 2012–2013, 2017–2018, 2021–2022) experienced widespread precipitation deficits, with approximately 89% of the study area showing below-average rainfall in 2022.
  • Significant soil moisture deficits were observed in 2008–2009, 2011–2015, and 2018.
• Temperatures increased consistently across all seasons, with a cumulative rise of approximately 1.5 °C over the study period, and record highs observed in 2023 and 2024.
  • Summer and autumn exhibited the strongest warming trends, with parts of southern and central areas experiencing warming rates above +0.06 °C per year.
• Cropland vegetation showed the strongest response to soil moisture variability during summer, with a lag time of approximately 2.8 months.
• Winter correlations were slightly lower, with the longest lag observed for precipitation at 3.5 months, highlighting seasonal differences in crop vegetation sensitivity to hydroclimatic drivers.
• A substantial share of cropland was frequently exposed to below-average precipitation and soil moisture, and above-average temperatures. For example, approximately 85% of cropland was affected by below-average precipitation in 2023, and approximately 90% experienced temperature stress in 2024.

Contributions

• Provides a comprehensive, long-term (2000–2024) spatiotemporal analysis of climate and soil moisture variability and its impact on cropland in western Yemen, a data-scarce and conflict-affected dryland region.
• Identifies specific seasonal trends and magnitudes of hydroclimatic changes (declining precipitation/soil moisture, rising temperatures) crucial for targeted agricultural adaptation strategies.
• Quantifies the lagged responses of cropland vegetation to hydroclimatic drivers, highlighting the critical role of soil moisture availability, especially during summer growing periods.
• Addresses a significant knowledge gap in the region regarding detailed climate-cropland interactions, offering valuable insights for informed land-use and water resource planning to enhance food security and agricultural resilience.

Funding

• CGIAR Climate Science Program (CASP) AoW-2 Digital Advisories and Climate Risk Management
• CGIAR Digital Transformation Accelerator (DTA) AoW-2 Actions Lab

Citation

@article{Ha2026Climate,
  author = {Ha, Tuyen and Govind, A and Thi, Nguyen Quang},
  title = {Climate and soil moisture variability and cropland exposure in Western Yemen: a spatiotemporal analysis using satellite and reanalysis time series from 2000 to 2024},
  journal = {Natural Hazards},
  year = {2026},
  doi = {10.1007/s11069-025-07828-6},
  url = {https://doi.org/10.1007/s11069-025-07828-6}
}