A new framework to identify most suitable priority areas for soil-water conservation using coupling mechanism in Guwahati urban watershed, India, with future insight

Abstract

The urban watershed of Guwahati, Assam, has witnessed a rapid urbanization in recent years, making it to one of the most deteriorated cities in terms of environmental issues. Therefore, this work focused on finding the most suitable soil-water conservation areas at a micro-scale using coupling coordination mechanism. Principal component analysis (PCA) was used to create a priority model for sub-watershed basin based on nineteen morphometric parameters. We then quantified the soil erosion using the revised universal soil loss equation (RUSLE) for current and future scenarios based on the representative concentration pathway (RCP) 2.6 and 8.5 models (RCP2.6 and 8.5). In addition, we proposed the fuzzy logic and analytical hierarchy process (AHP) model-based soil-water conservation suitability (SWPC) model for current and future scenarios. Finally, the most suitable soil-water conservation areas for current and future scenarios were identified using coupling coordination degree model (CCD). To the author's knowledge, this is the first in-depth study that identifies the most suitable conservation areas by analyzing the watershed prioritization, soil erosion, and topographic, hydrologic, land cover, and climatic parameters-based soil-water conservation suitability models. Sub-watersheds comprising Silsako, Bharalu, Deepor Beel, and North Guwahati have been identified as high-priority sub-watersheds. According to the current RUSLE model, soil erosion in the study area varies from 140 to 181.64 tonnes per hectare per year. In contrast, soil erosion would continue to increase in the future as per the RCP8.5 model, which varies from 305 to 332 tonnes per hectare per year. The current SWPC model predicted 46.92 km2 area as high and 54.40 km2 area as very high suitable zones. However, under the RCP 2.6 and RCP 8.5 models, the high and very high SWPC zones will experience extended areas in the future due to increased soil erosion intensity. According to the CCDM results, Bharalu, Deepor Beel, and North-Guwahati sub-watersheds have observed a very high to medium coupling degrees, which are considered the most suitable areas for conservation. The findings of this study will significantly help stakeholders and experts in long-term land-water resource management and effectively address environmental degradation issues in urban watersheds around the world.