Estimation of Surface Water Susceptibility to Pollution Index of Natural Wetlands of North-East India using Multi-Criteria Decision Model.

The study's primary goal was to develop the Surface Water Susceptibility to Pollution (SWSP) index to assess the health and quality of the wetland. This landscape is the best indicator of ecological and environmental conditions and serves as blue infrastructure for climate change adaptation.The study was conducted in the wetland-dominated area of the northeast region of India to demonstrate the scalability and replicability of the model. Eight independent watershed characteristics and fifty-five subfactors are included in the index for better performance at a larger scale. The water quality index (WQI) was measured through in situ and laboratory tests of the physicochemical parameters of surface water in three natural wetlands, namely Deepor Beel, Chandubi Lake, and Digholi Bil. WQI was used to validate the Susceptibility to Pollution (SWSP) index.The result revealed that Deepor Beel (Ramsar site, 2002) is highly turbid (73.6 NTU), and 96% of the geographical area of the lake has WQI values above 200, leading to the water being completely unsuitable for any usage. High and very highly SWSP regions of the catchment fall under built-up, agricultural land and hilly forest areas in Deepor Beel (72%), Digholi Bil (63%), and Chandubi Lake (62%). Linear regression between SWSP Index and WQI is significantly highly correlated in all three wetlands: Deepor Beel (R2 = 0.72), Chandubi Lake (R2 = 0.85) and Digholi Bil (R2 = 0.68) with p < 0.05. The SWSP index benefits water resource managers by assessing surface water quality and pollution status and adopting remedial measures to control pollution from non-point sources.