Summary
This study developed a practical method to estimate canopy cover from MODIS satellite NDVI data, calibrated against field measurements at the Walnut Gulch Experimental Watershed in Arizona. Regression analysis enabled spatially and temporally continuous canopy cover estimates suitable for input to water erosion prediction models. The approach was validated against the WEPP erosion model and found to improve representation of canopy variability compared to traditional point-based ground measurements, addressing a known limitation in erosion modelling for arid grassland environments.
Regional applicability
This study was conducted in the arid southwestern United States (Arizona) and may have limited direct applicability to UK conditions, which have different climate, vegetation types, and erosion regimes. However, the methodological approach of using satellite-derived vegetation indices to parameterise erosion models could be transferable to UK upland and grassland systems where similar remote-sensing data are available, though calibration would be required for temperate vegetation types and soil conditions.
Key measures
MODIS 250m NDVI (16-day temporal resolution), ground-measured canopy cover, soil loss predictions from WEPP erosion model
Outcomes reported
The study established regression relationships between MODIS NDVI satellite data and ground-measured canopy cover, and validated the approach for use in the WEPP water erosion model. Canopy cover estimates derived from satellite data were shown to capture spatial and temporal variability better than point ground measurements alone.
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