Sediment yield index (SYI) method for ranking of watersheds for soil and water conservation - A discussion

The Sediment Yield Index (SYI) holds significant importance in the context of watershed development prioritization and planning. The Sediment Yield Index (SYI) model was developed by the All India Soil and Land Use Survey (AISLUS), Government of India in 1969 to prioritize or rank watersheds for soil and water conservation. This article aims to review the SYI model and its usability for the government and scientific research communities. For review purpose about 500 published articles during the last 50 years (1973-2023), were searched to identify usage of the SYI model, out of which 213 search results were selected in this article. A total of 124 results came from river valley project reports based on field investigations [approximately 24.9% of the total geographic area of India, i.e., 328.7 million hectares, 25% of the surveyed area was classified as very high and high priority watersheds in 43 catchments], 45 journal articles were reviewed, of which 17 were indexed by Elsevier’s Scopus and 28 were non-Scopus articles; 31 reports related to the treatment of the catchment; and 13 articles related to the book chapters, symposium, conference proceedings, and capacity building. This study found that the SYI model has been used not only in India but also internationally by governments and scientific research organizations for prioritizing watershed categories in large geographical areas.