Jahangir et al. (2025) Comparison of different distributive functions based on drought indices: SRI and SSI in the Anzali watershed

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Identification

• Journal: Open MIND
• Year: 2025
• Date: 2025-08-09
• Authors: Mohammad Hossein Jahangir, Katayoon Sataryan Asil, Morteza Piran
• DOI: 10.82185/tsws.2025.1214420

Research Groups

Not specified

Short Summary

The study evaluates the most suitable cumulative distribution function for calculating drought using the Surface Runoff Index (SRI) and Standardized Surface Flow Index (SSI) within the Anzali watershed. It concludes that the Gamma distribution is the most appropriate for these indices in the study area.

Objective

• To identify the optimal cumulative distribution function for calculating drought based on the Surface Runoff Index (SRI) and the Standardized Surface Flow Index (SSI).

Study Configuration

• Spatial Scale: Anzali watershed (data collected from 10 stations).
• Temporal Scale: 30 years (1365–1394 SH / approx. 1986–2015 CE), with specific spatial zoning performed for the period 1385–1394 SH (approx. 2006–2015 CE).

Methodology and Data

• Models used: Surface Runoff Index (SRI), Standardized Surface Flow Index (SSI), Inverse Distance Weighting (IDW) interpolation, and various cumulative distribution functions (specifically testing the Gamma distribution).
• Data sources: Annual runoff and flow data from 10 stations; processed using MATLAB and ArcGIS.

Main Results

• The Gamma distribution was determined to be the most suitable function for the analysis.
• Statistical comparison revealed that the SRI and SSI indices exhibit similar trends in indicating drought conditions.
• Spatial zoning via IDW was successfully applied to the SRI for the 1385–1394 SH period.
• Severe drought was not observed across the watershed, with the sole exception of the Kharjgil station in the year 1369 SH (approx. 1990 CE).

Contributions

• Provides a comparative analysis of SRI and SSI indices in the Anzali watershed and establishes the Gamma distribution as the most effective statistical tool for drought calculation in this specific hydrological context.

Funding

Not specified

Citation

@article{Jahangir2025Comparison,
  author = {Jahangir, Mohammad Hossein and Asil, Katayoon Sataryan and Piran, Morteza},
  title = {Comparison of different distributive functions based on drought indices: SRI and SSI in the Anzali watershed},
  journal = {Open MIND},
  year = {2025},
  doi = {10.82185/tsws.2025.1214420},
  url = {https://doi.org/10.82185/tsws.2025.1214420}
}