ASSESSING EROSION CONTROL SUITABILITY WITH NORMALIZED DIFFERENCE INFRARED INDEX IN A SEMI-ARID WATERSHED

Abstract

Accurate assessment of soil moisture and infiltration capacity is essential for watershed management in semi-arid regions like Southern Arizona, USA. This study investigates the use of the Normalized Difference Infrared Index (NDII) to identify areas of low infiltration within the Walnut Gulch Experimental Watershed (WGEW), focusing on the driest (2020) and wettest (2022) monsoon seasons between 2015 and 2025. NDII, a remote sensing index sensitive to vegetation water content, serves as a proxy for root zone soil moisture. This study uses Landsat 8/9 imagery to analyze NDII changes between May and October and classify areas from low to high infiltration response. Comparing NDII change values across contrasting years highlights zones with persistent low infiltration. Identifying these areas is the first step toward developing a restoration strategy for semi-arid watersheds. A multi-criteria suitability analysis— incorporating slope, terrain ruggedness, road accessibility, and soil moisture data— prioritizes locations for erosion control structures (ECS). ECS offer a cost-effective restoration method by reducing water velocity and enhancing infiltration potential. Integrating NDII dynamics with hydrological and terrain factors provides a scalable, data-driven framework to support sustainable watershed restoration in arid environments.