Hydro-Ecological Response of Riparian Vegetation across Flood Susceptibility Zones in the Dudhnoi Watershed, Northeast India

Flooding is one of the primary environmental risks in Northeast India, often affecting riverine ecosystems. The riparian environment of the Dudhnoi watershed of Northeast India is significantly governed by the seasonal monsoon flooding. However, the relationship between flood vulnerability and the riparian vegetation condition response is not thoroughly researched. Riparian vegetation is a critical component of riverine ecosystems affecting bank erosion, sediment transport, nutrient cycling and habitat connectivity in floodplain environments. This study aims to analyse the state of riparian vegetation in various flood susceptibility zones by using an integrated GIS and remote sensing technique. Flood susceptibility was assessed using a GIS-based Multi-Criteria Decision Making (MCDM) flood susceptibility framework integrating topographic, hydrological, meteorological and land-use variables obtained from Sentinel-2, Landsat, SRTM DEM, rainfall and other associated geospatial datasets. Riparian zones were delineated by conducting a buffer analysis along the river network. Evaluation of vegetation condition, NDVI, EVI and NDMI using Sentinel 2 imagery (2016-2026) was performed in Google Earth Engine (GEE). The geographic relationships between vegetation status and flood susceptibility were assessed by correlation analysis and hotspot detection methods. The study indicates differences in the condition of the riparian vegetation in the different types of flood vulnerability zones in the watershed.  It offers a reference point for investigating hydro-ecological interactions that can support the restoration of river corridors, climate-resilient watershed management and ecosystem-based flood risk planning in monsoon-dominated river systems in Northeast India. These findings will help in better conservation planning and sustainable management of riparian habitats in Himalayan foreland river systems.