Document Type : Original Article
Authors
1 Member of Faculty of Geography and Environmental Sciences, Hakim Sabzevari University
2 Geographical Sciences and Social Studies Research Center, Hakim Sabzevari University, Sabzevar, Iran. m.zarei@hsu.ac.ir
3 Department Environment, South Khorasan Province, Birjand, Iran
Abstract
This study examines vegetation cover changes in the Kahneh watershed, over two periods: 2000–2012 and 2012–2024. As a semi-arid region, it is affected by climate change and precipitation fluctuations. The research assesses vegetation cover dynamics using NDVI, SPI, and monthly precipitation data within Google Earth Engine (GEE). NDVI data from satellite imagery was analyzed with SPI and monthly precipitation records. The study utilized GEE for large-scale remote sensing analysis. NDVI trends were examined across timeframes, and seasonal variations were assessed to determine the impact of precipitation fluctuations. SPI classified wet and dry years, linking precipitation anomalies with vegetation changes. NDVI values significantly increased in 2012–2024 compared to 2000–2012, indicating improved vegetation cover, especially in the later years. This improvement correlated with increased annual precipitation. However, SPI analysis revealed fewer wet years in 2012–2024, suggesting ongoing climate variability. Seasonal analysis showed vegetation cover improvements across all seasons, including dry periods, highlighting the positive effects of additional rainfall. The mean NDVI rose from 0.06 in 2000 to 0.10 in 2024, nearly doubling soil and vegetation improvement conditions. The study indicates that increased precipitation in 2012–2024 positively impacted vegetation cover in the Kahneh watershed. However, ongoing climate fluctuations and long-term climate change effects require further research. The study also highlights limitations in using only monthly data and emphasizes the need for integrating additional environmental factors for a more comprehensive analysis. This research provides insights into the effects of precipitation variability on semi-arid ecosystems, essential for sustainable land and water resource management.
Keywords
Main Subjects
)