Achite et al. (2025) Meteorological drought variability and its characterization in sub humid mediterranean region, the Wadi Isser basin of Algeria from 1970 to 2017

Identification

• Journal: Natural Hazards
• Year: 2025
• Date: 2025-10-24
• Authors: Mohammed Achite, S. Adarsh, Oğuz Şimşek, Abdelhak Bouharira, Arathy Nair Geetha Raveendran Nair, Tommaso Caloiero
• DOI: 10.1007/s11069-025-07693-3

Research Groups

• Faculty of Nature and Life Sciences, Laboratory of Water and Environment, University Hassiba Benboual of Chlef, Chlef, Algeria
• Department of Civil Engineering, TKM College of Engineering, Kollam, India
• Faculty of Engineering, Harran University, Şanlıurfa, Turkey
• National Research Council of Italy, Research Institute for Geo-Hydrological Protection (CNR˗IRPI), Rende, Italy

Short Summary

This study comprehensively analyzes meteorological drought variability and persistence in the Wadi Isser basin, Algeria, from 1970 to 2017 using the Standardized Precipitation Index (SPI), various trend tests, and Hurst exponent estimation. It reveals decreasing short-term droughts in northern/southern regions, increasing long-term droughts in central/eastern regions, and identifies a significant climate shift around 1997-1998 as a key modulator of drought conditions and persistence.

Objective

• To perform a trend analysis of SPI at different time scales (1-, 3-, 6-, 9-, 12-, and 24-month) for the period 1970–2017 at 26 precipitation observation stations using the Mann–Kendall (MK) and Modified Mann–Kendall (MMK) methods, and to connect these results with rainfall trends.
• To analyze the transitions of trend and to detect change points in the SPI series using the Sequential Mann–Kendall (SQMK) test.
• To estimate the persistence and analyze the predictability of different SPI series within the basin.

Study Configuration

• Spatial Scale: Wadi Isser basin, Central-Northern Algeria, covering an area of approximately 4147 square kilometers (between 35° 53′ and 36° 51′ N latitude and 2° 53′ and 3° 57′ E longitude). Data from 26 precipitation gauging stations.
• Temporal Scale: Monthly rainfall data from 1970 to 2017 (48 years). SPI calculated for 1-, 3-, 6-, 9-, 12-, and 24-month time scales.

Methodology and Data

• Models used:
  • Standardized Precipitation Index (SPI)
  • Mann–Kendall (MK) test
  • Modified Mann–Kendall (MMK) test
  • Sequential Mann–Kendall (SQMK) test
  • Hurst exponent estimation using Rescaled Range (RSR) and Aggregated Variance (AV) methods
  • Derived persistence parameters: Fractal Dimension (D), Predictability Index (PI), and Lag-1 Autocorrelation (r)
• Data sources: Monthly rainfall data from 26 gauging stations within the Wadi Isser basin, obtained from the National Agency of Water Resources (ANRH). Data homogeneity assessed using the double mass curve technique, and missing values filled using linear regression.

Main Results

• The driest periods in the Wadi Isser basin predominantly occurred between 1987 and 2002.
• Mean critical drought durations increase with the SPI time scale, ranging from 9.42 months for SPI 1 to 64.38 months for SPI 24.
• Trend analyses (MK and MMK) show decreasing trends in short-term droughts (SPI 1, SPI 3) in the northern and southern regions, while long-term droughts (SPI 9, SPI 12, SPI 24) exhibit increasing trends in the central and eastern parts of the basin.
• The SQMK test identified a significant change point in most SPI series between 1995 and 2000, indicating the influence of the 1997–1998 global climatic shift on regional drought conditions.
• Monthly rainfall series generally show weak persistence (Hurst exponent values between 0.5 and 0.6), whereas SPI series (except SPI 1 in three stations) exhibit long-term persistence, with persistence increasing as the time scale lengthens.
• The eastern part of the basin is characterized by high drought persistence across all time scales.
• Predictability of drought events increases with the aggregation time scale, with short-term droughts being more complex and less predictable compared to medium and long-term droughts.
• SPI 24 shows the least variability and highest mean values for persistence parameters (Hurst exponent, predictability index, lag-1 autocorrelation), indicating its high predictability.

Contributions

• Provides a comprehensive and innovative framework for meteorological drought analysis in the Wadi Isser basin, integrating advanced trend and persistence techniques.
• Advances the understanding of drought behavior by incorporating the Hurst exponent (via RSR and AV), fractal dimension, lag-1 autocorrelation, and a predictability index, which are crucial for long-term climate adaptation strategies.
• Identifies significant change points in the temporal drought record using the Sequential Mann–Kendall test, linking regional drought dynamics to global climatic shifts (e.g., the 1997–1998 El Niño event).
• Offers valuable insights into the predictability of future drought occurrences, which can inform early warning systems and proactive water management policies in semi-arid regions.
• Establishes a valuable reference for future research, climate resilience planning, and policy formulation in Mediterranean basins with similar climatic conditions.

Funding

• Consiglio Nazionale Delle Ricerche (CNR) within the CRUI-CARE Agreement.
• National Agency of the Water Resources (ANRH) for data collection.
• General Directorate of Scientific Research and Technological Development of Algeria (DGRSDT).

Citation

@article{Achite2025Meteorological,
  author = {Achite, Mohammed and Adarsh, S. and Şimşek, Oğuz and Bouharira, Abdelhak and Nair, Arathy Nair Geetha Raveendran and Caloiero, Tommaso},
  title = {Meteorological drought variability and its characterization in sub humid mediterranean region, the Wadi Isser basin of Algeria from 1970 to 2017},
  journal = {Natural Hazards},
  year = {2025},
  doi = {10.1007/s11069-025-07693-3},
  url = {https://doi.org/10.1007/s11069-025-07693-3}
}