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Spatial Pattern of Drought Indicators Trend Change in Gilan Province
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Leila Haghparast   , Bahman Ramzani *1 , Atoosa Bigdeli , Yousef Zeinolabedin |
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Abstract: (17 Views) |
Introduction: One of the consequences of changes in temperature and precipitation is drought, the persistence and recurrence of which are associated with destructive environmental impacts. This study investigates drought as the most significant outcome of temperature and precipitation variations.
Materials and Methods: Initially, the required data were obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) with a spatial resolution of 0.25° × 0.25° over a period of 44 years (1980 to 2023). The presence of trends in the Standardized Precipitation Index (SPI) and the Reconnaissance Drought Index (RDI) was determined using the Mann-Kendall test. Additionally, the Local Moran’s I statistic (ALMI) was applied to identify the spatial pattern of these indices.
Results: The results showed that the RDI exhibited a significant decreasing (negative) trend in the months of March, May, June, and August.
Conclusion: In addition to the negative trend in the mean RDI values during March, May, June, and August, a negative trend was also confirmed at the individual grid cells for these months. Spatial analysis using the trend test and Local Moran’s I of the drought indices (RDI and SPI) revealed distinct high-high (HH) and low-low (LL) clusters in various parts of the province, ranging from plains to mountainous areas and from east to west, forming separate cores. This indicates a non-random spatial distribution pattern for the RDI and SPI indices.
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Article number: 4 |
| Keywords: : Trend, Local Moran’s I, SPI, RDI, Gilan Province |
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Full-Text [PDF 2279 kb]
(21 Downloads)
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Type of Study: Research |
Subject:
Special
Received: 2025/07/21 | Accepted: 2025/11/16 | Published: 2026/01/13
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