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Evaluating Watershed Response to Meteorological Drought in the Propagation Process to Hydrological Drought at the Event Scale
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Mohammad Rostami Kalaj *   , Hamze Noor , Ali Bagherian Kalat |
| Assistant Professor, Department of Soil Conservation and Watershed Management Research, Khorasan Razavi Agricultural and Natural ResourcesResearch and Education Center, AREEO, Mashhad, Iran |
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Abstract: (49 Views) |
| Drought is one of the most critical climatic hazards in arid and semi-arid regions, where persistent water shortages impose substantial environmental and economic impacts. Understanding the propagation of meteorological drought into hydrological drought is a fundamental step toward sustainable water resource management. This study investigates the relationship between meteorological drought characteristics and event-scale propagation ratios, and assesses the sensitivity of watersheds in Khorasan Razavi Province to this propagation process. Using monthly precipitation and streamflow data from 46 catchments over a 29-year period, we computed the Standardized Precipitation Index (SPI) and the Standardized Streamflow Index (SSI). Exponential relationships were fitted between standardized propagation ratios and meteorological drought characteristics (severity and intensity), and sensitivity coefficients were derived for each catchment. The results show that propagation ratios decrease exponentially with increasing meteorological drought severity and intensity across all catchments. The average coefficients of determination for the severity- and intensity-based relationships were 0.43 and 0.48, respectively, with over 85% of the catchments exhibiting statistically significant fits. Among the studied basins, the Mosheng catchment showed the highest sensitivity (severity sensitivity = 2.29; intensity sensitivity = 1.77), whereas the Dahaneh-Shur catchment exhibited the lowest (severity sensitivity = 1.08; intensity sensitivity = 0.92), indicating more stable hydrological behavior. A significant negative association was also found between snow fraction and severity sensitivity, suggesting that a higher contribution of snowfall reduces the magnitude of drought propagation. Overall, the findings highlight substantial spatial heterogeneity in catchment responses to drought propagation and underscore the critical role of climatic and physiographic controls. These results provide a scientific basis for identifying vulnerable catchments and for developing adaptive water management strategies in the dry regions of Iran. |
Article number: 4 |
| Keywords: SPI, SSI, Drought Severity, Watershed Sensitivity Coefficient, Exponential Propagation Model |
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Type of Study: Research |
Subject:
Special
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