Akhundzadah (2026) Investigating climate change impacts from hydroclimatic trends and land cover change in Afghanistan’s Helmand River Basin

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2026
• Date: 2026-01-12
• Authors: Noor Ahmad Akhundzadah
• DOI: 10.1007/s00704-025-05914-0

Research Groups

• Department of Natural Resources and the Environment, College of Agriculture & Life Sciences, Cornell University, Ithaca, NY, USA

Short Summary

This study provides an integrated assessment of hydroclimatic trends and land cover changes in Afghanistan's Helmand River Basin (1980-2023), revealing significant warming, decreased precipitation, and reduced river discharge, which has led to substantial shrinkage of water bodies and green cover.

Objective

• To analyze long-term trends (1980-2023) in mean annual temperature, precipitation, and river discharge, and assess land cover changes (1992-2020) in Afghanistan's Helmand River Basin to understand the integrated impacts of climate change on water resources, agriculture, and ecosystems.

Study Configuration

• Spatial Scale: Helmand River Basin (HRB), Afghanistan, covering approximately 341,543 km², including its upper, middle, and lower regions, and four key hydrological stations (Zaranj, Farah, Qala-i-Bust, Gizab).
• Temporal Scale: Hydroclimatic trends: 1980–2023 (44 years). Land cover changes: 1992 and 2020 (comparison). Climatic conditions description: 2013–2022.

Methodology and Data

• Models used:
  • GFDL-ESM4 (Geophysical Fluid Dynamics Laboratory Earth System Model version 4.1) for temperature and precipitation.
  • GloFAS-ERA5 (Global Flood Awareness System, forced by ERA5 reanalysis) for river discharge, which utilizes the LISFLOOD hydrological model.
• Data sources:
  • GFDL-ESM4 (1° × 1° gridded dataset) for mean annual temperature and precipitation (1980-2023).
  • GloFAS-ERA5 (0.05° × 0.05° gridded dataset) for river discharge (1979-2023).
  • ESA CCI-LC version 2.0.7 (European Space Agency Climate Change Initiative Land Cover) for land cover classifications (1992, 2020).
  • CRU TS v4 (Climate Research Unit) for mean monthly temperature and precipitation (2013-2022, for climatic description).
  • Statistical methods: Innovative Trend Analysis (ITA), Mann-Kendall (MK) test, Sen’s Slope (SS) estimator.
  • Software: ArcGIS Pro 3.4.2, Python 3.9.

Main Results

• Temperature: A significant upward trend (p < 0.001) was observed across the HRB, with the mean annual temperature increasing by approximately 1.67 °C (Sen's Slope) to 2.38 °C (ITA) over the 44-year study period (1980-2023). The upper basin experienced the most substantial increase (~2.11 °C).
• Precipitation: A consistent downward trend was detected across all sub-regions (1980-2023). Total annual precipitation decreased by approximately 37–68 mm, with the most significant reduction in the upper zone.
• River Discharge: Statistically significant decreasing trends were found at Zaranj, Farah, and Qala-i-Bust gauging stations (p < 0.05). Annual decline rates were estimated at -5.708 m³/s at Zaranj, -1.480 m³/s at Farah, and -5.519 m³/s at Qala-i-Bust. Zaranj experienced a total decrease of approximately 257 m³/s over the study period.
• Land Cover Change (1992-2020):
  • Surface water extent significantly decreased by approximately 2,142 km².
  • Natural vegetation categories, including shrubland (-1,450 km²) and mosaic vegetation (-1,985 km²), showed significant shrinkage.
  • Irrigated agriculture expanded by approximately 1,434 km², and grassland increased by about 5,784 km².
  • Urban areas doubled from 138 km² to 279 km².
• Overall, the HRB experienced an average annual temperature increase of nearly 2 °C, a 13.4% decrease in yearly precipitation, and a 26% reduction in river discharge.

Contributions

• Provides an integrated, basin-scale assessment (1980–2023) of hydroclimatic trends and land cover changes, linking river discharge trends to mapped surface-water shrinkage and quantifying downstream flow reductions.
• Quantifies and validates long-term hydroclimatic trends using bias-independent global gridded datasets, addressing skepticism regarding the causes of declining Helmand River discharge (i.e., distinguishing climate impacts from upstream diversions).
• Offers crucial insights for transboundary water diplomacy, basin-wide resource management, and future climate change mitigation and adaptation strategies in a data-scarce region.

Funding

• The author declares that this research has not received funds.

Citation

@article{Akhundzadah2026Investigating,
  author = {Akhundzadah, Noor Ahmad},
  title = {Investigating climate change impacts from hydroclimatic trends and land cover change in Afghanistan’s Helmand River Basin},
  journal = {Theoretical and Applied Climatology},
  year = {2026},
  doi = {10.1007/s00704-025-05914-0},
  url = {https://doi.org/10.1007/s00704-025-05914-0}
}