Assessment of groundwater resources vulnerability, reliability and resilience under drought condition (Case study: Dehgolan plain, Kurdistan province)

Extended Abstract
Introduction
Groundwater resources play a vital role in sustaining socio-economic development, particularly in arid and semi-arid regions where surface water is scarce. In recent decades, these resources have come under increasing stress due to climate change, prolonged droughts, and unsustainable abstraction. The vulnerability of aquifers to drought has therefore become a central issue in water resources management and policy-making. The resilience, reliability, and vulnerability (RRV) framework provides a robust means to assess the performance and sustainability of groundwater systems under hydrological stress. This study focuses on evaluating the groundwater resources of the Dehgolan plain, located in Kurdistan Province, Iran, to determine their vulnerability, reliability, and resilience in the face of recurrent droughts. The Dehgolan plain is one of the most important agricultural zones in the region, yet it has experienced significant groundwater decline over the past few decades. Continuous extraction for irrigation, coupled with reduced precipitation and recharge, has led to critical drops in groundwater levels and deterioration in aquifer storage. Using long-term hydrological and meteorological data, this research aims to (1) quantify the temporal and spatial variations of drought intensity and duration, (2) assess groundwater system behavior during drought events, and (3) evaluate overall aquifer performance through the RRV indices. The results provide a scientific foundation for improving groundwater management strategies in drought-prone regions.
Materials and Methods
The study area encompasses the Qorveh–Dehgolan plain in eastern Kurdistan Province, bounded by latitudes 34°56′ to 35°02′ N and longitudes 47°07′ to 47°24′ E. The region is characterized by a cold semi-arid climate with an average annual precipitation of approximately 350 mm and average temperatures ranging from –23°C to 41°C. The study utilized data from seven meteorological stations and 54 observation wells covering the 1977–2022 period. Drought assessment was performed using two major indicators: The Standardized Precipitation Index (SPI) for meteorological drought and the Groundwater Resource Index (GRI) for hydrogeological drought. SPI values were calculated for 6- and 12-month timescales using gamma probability distribution fitting. GRI was derived by standardizing deviations of monthly groundwater levels from their long-term means, thereby reflecting groundwater storage anomalies. Reliability (Rel) represents the probability of the system being in a satisfactory state, Resiliency (Res) measures the speed of recovery after a drought, and Vulnerability (Vul) quantifies the magnitude of failure when the system departs from acceptable conditions.
Results and Discussion
The SPI analysis revealed alternating wet and dry cycles, with severe droughts during 1977–1981, 1987–1992, and 1997–2001. SPI values ranged from –1.8 to +1.8, indicating alternating meteorological extremes and a general decline in precipitation after 1990. The GRI results showed continuous groundwater depletion, particularly in the central and eastern zones of the plain, where water-level declines exceeded 20 m. Average drought duration varied between 1.5 and 3.5 months, while 16–32% of the observation wells experienced recurrent droughts. RRV indicators quantified system performance under drought stress. Reliability values ranged from 0.91 to 0.94 (mean 0.92), showing that the aquifer remained in a satisfactory state most of the time. Resilience ranged between 0.72 and 0.95 (mean 0.82), reflecting moderate recovery capacity after drought. Vulnerability values varied from 0.23 to 0.39 (mean 0.31), signifying moderate failure magnitude. The composite RRV index averaged 0.62 based on SPI data and 0.68 using GRI data, representing a moderately stable yet declining system. Spatially, higher RRV values occurred in northern sectors, while central and southern zones exhibited reduced resilience and higher vulnerability. Overall, the findings indicate that although the Dehgolan aquifer retains moderate reliability, its recovery capacity has weakened due to prolonged overexploitation and limited recharge. These results align with previous research in western Iran, confirming that unsustainable groundwater abstraction combined with persistent droughts is reducing aquifer stability and resilience.
Conclusion
The integrated analysis of meteorological and groundwater droughts in the Dehgolan plain demonstrates that the aquifer system is under increasing pressure, primarily driven by climatic variability and excessive abstraction. The combined use of SPI, GRI, and RRV indices proved effective in identifying spatial and temporal patterns of groundwater vulnerability and in quantifying the system’s performance under drought stress. The mean reliability value (≈0.92) indicates that the groundwater system generally maintains acceptable performance, but the moderate resilience (≈0.82) and vulnerability (≈0.31) highlight limitations in recovery capacity and the potential for further degradation if current extraction rates persist. The RRV index values (0.62–0.68) collectively suggest a moderately stable yet increasingly fragile system. To enhance groundwater sustainability, it is essential to implement adaptive management strategies such as controlled abstraction, artificial recharge, improved irrigation efficiency, and continuous monitoring of groundwater levels. The results of this study provide a quantitative foundation for policymakers and regional planners to develop drought mitigation frameworks and long-term groundwater management plans aimed at preserving aquifer resilience and reliability under future climatic uncertainties.