Assessment of vegetation and soil water regimes in partial canopies with optical remotely sensed data

Abstract

The optical properties of a partially vegetated cotton field with spatially and temporally dynamic soil water conditions were analyzed with coincident aircraft and satellite data. The study was conducted at the Maricopa Agricultural Center in Arizona during June 1988. The dynamics of soil surface drying made it difficult to evaluate plant cover and assess soil condition with combined thermal, brightness, and normalized difference vegetation index (NDVI) spectral parameters as all three parameters were sensitive to the three stages of soil drying. A soil-adjusted vegetation index (SAVI) minimized both spatial and temporal variations in soil spectral behavior and was found useful in vegetation analysis and in further qualitative assessment of soil condition. Due to the complex dynamics of soil surface drying and variability in soil properties, soil water content at the surface (0 - 5 cm) could not be determined with the Thematic Mapper moisture bands, or with the various "wetness" indicators. © 1990