Using AVHRR NDVI (normalized difference vegetation index)

IGBP land cover and CRU meteorological database

potential evapotranspiration (PET) over Hanjiang River basin in 1981-2000 was estimated by Shuttleworth-Wallace (S-W) model. Spatially

PET was distributed over the basin strikingly non-uniformly from 714.8 mm to 1 570.7 mm yearly

mainly because of the influence of land cover types and geographical location. Temporally

PET changed significantly with vegetation seasonal development

thus with vegetation leaf area index (LAI). Temporal and spatial resolutions of input data greatly affected PET estimation accuracy. Compared with Thornthwaite formula and FAO-56 method

S-W model can reflect the effects of vegetation change on PET very well. By applying the derived PET to a distributed hydrological model - BTOPMC

good results was achieved in the Hanjiang River basin.