Evaluation of Ratio-Based Vegetation Indices For Annual Crops’ Biomass Estimation. Lebna Watershed, Capbon, Tunisia

The sustainability of agricultural sector involves a wise water resources management and therefore an accurate spatiotemporal vegetation monitoring with relevant tools such as satellite-derived indices (VI). In this study we evaluate the performance of NDVI and NDWI indices to infer the annual crops' (mainly wheat and faba-bean) aboveground biomass(AGB)at a Mediterranean watershed. The temporal evolution of IV over the annual crops' area shows the presence of low-density and low water content vegetation in early and late season. Areas with well-developed canopy and high plant water content are dominant in the mid-season. The observed AGB of wheat and faba-bean shows a good correlation with NDVI and NDWI values $(\mathrm{R}^{2} \gt 0.71)$. The used vegetation indices represent a practical tool to determine the spatiotemporal variation of annual crops' AGB in Lebna watershed, however, a large dataset for validation is needed.