Dariane et al. (2025) Reevaluating streamflow declines across the middle East and central Asia with insights from change point detection

Identification

• Journal: Scientific Reports
• Year: 2025
• Date: 2025-12-19
• Authors: Alireza B. Dariane, Mahboobeh Ghasemi
• DOI: 10.1038/s41598-025-32722-3

Research Groups

• Department of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran.

Short Summary

This study identifies 1998 as a critical regional breakpoint for streamflow declines across the Middle East and Central Asia, primarily triggered by the 1997–1998 El Niño event. While climate anomalies initiated these shifts, the research demonstrates that subsequent human activities, such as irrigation expansion, significantly amplified the magnitude of hydrological stress.

Objective

• To detect abrupt change points in streamflow across the Middle East, Central Asia, and Pakistan.
• To analyze the relative contributions of climate variability and human activities to observed streamflow reductions.
• To evaluate the reliability of change point detection (CPD) methods in attributing hydrological changes to specific drivers.

Study Configuration

• Spatial Scale: Regional analysis covering the Middle East (Iran, Iraq, Oman, Syria, Jordan, Turkey, Egypt, UAE, Israel, Lebanon), Central Asia (Kazakhstan, Uzbekistan, Turkmenistan, Afghanistan, Tajikistan, Kyrgyzstan), and Pakistan; includes a high-resolution case study of the Karkheh River Basin (KRB) in Iran.
• Temporal Scale: 1970–2018 (Annual and daily time series).

Methodology and Data

• Models used: Pettitt test, Standard Normal Homogeneity Test (SNHT), Buishand range test, Ordered Clustering (OC), Cumulative Anomaly tests, Sen’s slope estimator (for trend analysis), and CROPWAT model (for estimating crop water requirements).
• Data sources: Global Runoff Data Centre (GRDC), Global Flood Awareness System (GloFAS/CEMS), ERA5 reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF), and ground-based hydro-climatic records from the Iran Water Resources Management Organization and the Ministry of Agriculture Jahad.

Main Results

• Regional Breakpoints: 1998 was the most frequent year for abrupt streamflow shifts across the Middle East and Central Asia, coinciding with the strongest recorded El Niño event (1997–1998).
• Hydrological Decline (KRB): In the Karkheh River Basin, average streamflow dropped by 53.6% after the 1998 breakpoint, whereas precipitation only decreased by 5.7% during the same period.
• Thermal Shifts: Average annual temperatures in the KRB increased by approximately 1.7 °C in the post-1998 period compared to the 1970–1998 reference period.
• Anthropogenic Drivers: Irrigated agricultural land in the KRB increased by 67% compared to the 1982–1983 base level, with the most intensive expansion occurring after 2001.
• Water Demand: Modeling indicates that a 1 °C to 2 °C temperature rise increases crop water requirements by approximately 5% to 15%, further straining water resources.

Contributions

• Provides a comprehensive regional assessment of hydrological stationarity across two climate-vulnerable regions.
• Critically reevaluates the interpretation of statistical breakpoints, arguing that the late-1990s shifts often attributed to human activity were likely triggered by large-scale climatic signals (ENSO).
• Highlights the "amplification effect" where human interventions (dams, irrigation) sustain and worsen hydrological declines initially sparked by natural climate variability.

Funding

• The authors declare that no specific funding was used for this research.

Citation

@article{Dariane2025Reevaluating,
  author = {Dariane, Alireza B. and Ghasemi, Mahboobeh},
  title = {Reevaluating streamflow declines across the middle East and central Asia with insights from change point detection},
  journal = {Scientific Reports},
  year = {2025},
  doi = {10.1038/s41598-025-32722-3},
  url = {https://doi.org/10.1038/s41598-025-32722-3}
}

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