Spatiotemporal mapping and monitoring of wetland transformations and algal bloom patterns in Sambhar Lake, India
摘要
Sambhar Lake ecosystem, India’s largest inland saline wetland ecosystem, has undergone siginificant hydrological and land-use changes in recent decades. The current study integrates remote sensing and geospatial analysis to assess land use/land cover (LULC), water extent seasonality, algal bloom patterns, and long-term wetland transitions in Sambhar Lake under 2 km buffer. LULC classification for the monsoon season of 2023 identified eleven classes, with water accounting for the largest share (24.7%), followed by cropland (20.4%), fallow land (14.3%), grassland (11.6%), and saline land (11.2%). Monthly water extent analysis for 2022 and 2023 revealed strong monsoonal control, with peak inundation during July–September and marked shrinkage during the summer season. Seasonal analysis revealed a decline in natural water surface from 131 km2 (2022) to 117 km2 (2023), alongside an increase of salt pan from 49.5 to 51.5 km2. Algal bloom monitoring indicated distinct seasonal variability concentrated along the lake periphery. They have peak occurrence during pre-monsoon season when water is less. They covered 43.6% of the total water surface in 2022 and 34.6% in 2023, indicating short-lived but concentrated seasonal peaks. In a long-term analysis (1984-2023) newly formed seasonal water area accounted for 99.1 km2, gains in permanent natural water were minimal. The study emphasizes the need to distinguish industrial salt pans from natural wetland area in conservation and management planning.