Prioritization of Watershed using Sediment Yield Index Method: A Case study of Semi-Arid Ecosystem of South India

Article history: Received 03 May 2020 Received in revised form 06 August 2020 Accepted 30 November 2020 Available online 08 January 2021 Abstract Soil erosion is a severe problem in arid and semi-arid environments, especially on grazing land, where extreme rainfall intensities of short duration, soil vulnerability to erosion, and human land mismanagement have increased soil degradation by erosion leading to sedimentation downstream. For the better agricultural sustainable development, estimation of soil sedimentation is critical for watershed planning, prioritization and development. A sediment yield index (SYI) model describing the relative yield of sediments from various sub-watersheds works out the preferences for soil and water conservation interventions in a watershed. The study recognizes the extent of soil loss and recommends a method for prioritization of sub-watershed in the Sarabhanga watershed of Tamil Nadu state by integrating the topography, soil, rainfall erosivity and land use/land cover parameters under 17 subwatersheds with a Geo-informatics approach. Of the 17 sub-watersheds, five sub-watersheds (SB-6, SB-3, SB-14, SB-12 and SB-5) came into the extremely high priority category, with a higher SYI value (>170) and covering 584.3 sq. km, about 49.7% of the Sarabhanga watershed due to high rainfall and high slope value imply that these sub-watersheds have a high potential for erosion and sedimentation. Six sub-watersheds (SB-1, SB-11, SB-2, SB-13, SB-4 and SB-15) were classified under a low priority class covering an area of 233.4 sq.km (19.9%) and these sub-watersheds have low amounts of precipitation and less than 70 SYI values. The study comments on conservation techniques that can be adopted in the Sarabhanga watershed to the increase agro pastoral efficiency.