Use of spectral information for wetland evapotranspiration assessment

A geographic information system (GIS) and the newly developed normalized difference vegetation index (NDVI)–diurnal surface temperature variation (DSTV) triangle method was used to estimate water evaporation and transpiration from wetlands in Florida. Spectral information from NOAA AVHRR thermal and visible/near-infrared bands was used to generate the DSTV and the NDVI, respectively. The concept of NDVI–DSTV triangle was developed, based on the pattern of known land-cover located in the NDVI–DSTV scattergram, to determine the fractional contributions for each natural land surface from vegetation, dry- and wetland surfaces. The vegetation and moisture coefficient (VMC) was estimated for calculation of actual evapotranspiration (ET). GIS was utilized to manage the data and to estimate the VMC. Regional ET was then estimated from the data layers in the GIS. ET derived from remote sensing, was then compared with lysimeter measurements in south Florida wetlands. Results indicated a successful estimation of regional wetland ET.