Sharifi et al. (2026) Introducing Resiliency as a Novel Metric for Enhanced Drought Monitoring

Identification

• Journal: Rangeland Ecology & Management
• Year: 2026
• Date: 2026-03-13
• Authors: Mohammad Reza Sharifi, M Nouri, Amin Abdi Dezfuli
• DOI: 10.1016/j.rama.2026.02.002

Research Groups

• Department of Hydrology and Water Resources, Shahid Chamran University of Ahvaz, Ahvaz, Iran
• Department of Water Resources, Shahid Chamran University of Ahvaz, Ahvaz, Iran
• Department of Agriculture Meteorology, University of Tehran, Tehran, Iran

Short Summary

This study introduces resiliency as a novel metric for dynamic drought monitoring, demonstrating its effectiveness in assessing recovery potential across different drought types (meteorological, hydrological, groundwater, and combined) in the Aleshtar subbasin, Iran, using 30 years of hydroclimatic data.

Objective

• To improve drought dynamics analysis by introducing and evaluating the resiliency index, which quantifies how quickly and effectively a natural system recovers after a drought, using four hydroclimatic indices (Standardized Precipitation Index (SPI), Standardized Runoff Index (SRI), Standardized Groundwater Index (SGI), and Standardized Runoff–Groundwater Index (SRGI)) in the Aleshtar subbasin, Iran.

Study Configuration

• Spatial Scale: Aleshtar subbasin, Karkheh river basin, Lorestan Province, western Iran, covering approximately 811 square kilometers.
• Temporal Scale: Monthly data from 1991 to 2020 (30 years), analyzed in six 5-year periods.

Methodology and Data

• Models used:
  • Standardized Precipitation Index (SPI)
  • Standardized Runoff Index (SRI)
  • Standardized Groundwater Index (SGI)
  • Standardized Runoff–Groundwater Index (SRGI), calculated using copula functions (Frank, Clayton, Gumbel, Joe). Frank's copula was selected as the best fit.
  • Probability distribution functions for fitting: Log-Pearson III (P-III), Gamma, Generalized Extreme Value (GEV), and Log-Normal (Log-N). GEV was predominantly selected.
  • Resiliency index (based on Ashofteh et al., 2015)
• Data sources:
  • Monthly precipitation data
  • Monthly streamflow (discharge) data from Sarab Seyed Ali station
  • Monthly groundwater levels from 13 observation wells, obtained from the Lorestan Regional Water Authority

Main Results

• The resiliency index effectively quantifies the potential for a system to return to normal conditions after a drought, both within individual drought types and across different types.
• SPI, SRI, and SRGI showed no significant trends in resiliency over the study period, with average resiliency values of 46.4%, 37.4%, and 52.2%, respectively.
• SGI (groundwater drought) exhibited a significant structural shift, with its resiliency declining sharply from 100% (1991–1995) to 36.9% (2016–2020), indicating increased persistence and lower recovery potential primarily due to higher groundwater extraction.
• On average, hydrological (SRI, 37.4%) and groundwater (SGI, 34.7%) droughts demonstrated lower resiliency compared to meteorological (SPI, 46.4%) droughts, highlighting their greater persistence.
• The combined SRGI showed the highest average resiliency at 52.2%, surpassing that of individual SRI and SGI, suggesting that integrated monitoring provides a more realistic assessment of drought conditions and recovery potential due to hydraulic interconnections between surface and groundwater.
• An inverse relationship was consistently observed between resiliency and mean drought duration, validating resiliency as an effective metric for quantifying recovery capacity.

Contributions

• Introduces and validates the resiliency index as a novel, dynamic metric for drought monitoring, offering a more comprehensive understanding of drought dynamics beyond traditional static measures like duration and frequency.
• Provides a new framework for dynamic drought analysis that explicitly quantifies system recovery potential, which is crucial for developing climate-resilient management policies, particularly in arid and semi-arid regions.
• Demonstrates that a combined hydrological and groundwater drought index (SRGI) offers a more realistic and resilient assessment of drought conditions compared to individual surface water or groundwater indices, due to the hydraulic interconnections.
• Offers valuable insights into the differential recovery dynamics of meteorological, hydrological, and groundwater droughts, highlighting the increased vulnerability and slower recovery of groundwater systems.
• Supports rangeland monitoring programs by providing a metric to assess ecosystem stability and adaptive capacity under recurrent climatic stress, with conceptual transferability to other rangeland-relevant variables.

Funding

• Shahid Chamran University of Ahvaz grant, SCU.WH1401.26878.

Citation

@article{Sharifi2026Introducing,
  author = {Sharifi, Mohammad Reza and Nouri, M and Dezfuli, Amin Abdi},
  title = {Introducing Resiliency as a Novel Metric for Enhanced Drought Monitoring},
  journal = {Rangeland Ecology & Management},
  year = {2026},
  doi = {10.1016/j.rama.2026.02.002},
  url = {https://doi.org/10.1016/j.rama.2026.02.002}
}