Authors: Saurabh Singh
Abstract: Large-scale mass gathering events can substantially influence riverine environments through intense anthropogenic activities, sediment disturbance, and rapid alterations in surface water char-acteristics. The present study investigates the spatial variability of Sentinel-2 spectral reflectance and water surface characteristics in the Prayagraj Sangam region during Mahakumbh 2025 using multispectral satellite imagery and cloud-based geospatial analysis. Sentinel-2 MultiSpectral In-strument (MSI) imagery acquired through the Google Earth Engine (GEE) platform was utilized to evaluate variations in spectral reflectance associated with major bathing activities and river surface disturbances during the event period. The study primarily focused on the analysis of green (B3), red (B4), and near-infrared (B8) spectral bands along with the Normalized Difference Water Index (NDWI) for assessing river surface characteristics and spatial environmental varia-bility. Spatial analysis was performed to identify reflectance hotspots and disturbed river sections influenced by intense human activities, ritual bathing, temporary settlement expansion, and riverbank interactions during Mahakumbh 2025. The generated spectral reflectance maps revealed considerable spatial heterogeneity across the study area, particularly near the Sangam confluence and major bathing ghats. Elevated reflectance values and noticeable variations in NDWI distribu-tion were observed in regions experiencing high anthropogenic pressure and continuous river surface disturbances. The analysis further demonstrated distinct differences in spectral behavior between relatively stable river sections and highly occupied bathing zones. The study highlights the capability of Sentinel-2 imagery and Google Earth Engine for rapid and large-scale monitoring of dynamic river environments during mass gathering events. The integra-tion of multispectral satellite observations with geospatial analysis provides a cost-effective and efficient framework for identifying spatial environmental disturbances and evaluating river sur-face variability in highly populated riverine systems. The findings of the study may contribute toward improved satellite-based environmental monitoring, river management strategies, and sustainable assessment of anthropogenic impacts during large religious gatherings such as Maha-kumbh.
DOI: http://doi.org/10.5281/zenodo.20270657
