Using remote sensing to estimate water use efficiency in Western China

In this paper, the Common Land Model (CLM) and the Monteith type carbon model-C-FIX were applied to estimate the water use efficiency (WUE) of western China in 2002. The input data mainly included NCAR and Meteo France meteorological data sets, 1 km USGS soil and land cover data, the global 0.25deg monthly MODIS LAI data and the 1 km VGT-S10 NDVI products. Some field measurements of WUE for different plants in the study area were used for validation. The total annual NPP and actual ET in western China in 2002 were estimated about 0.96PgC and 2098km³ H₂O. The mean annual WUE per square meter was about 0.32gC/mm. The spatial pattern of the mean annual WUE in Western China as well as the seasonal WUE profiles of different ecosystems were illustrated and descript in detail. In general, the mean annual WUE of the main ecosystems in western China were ranked as: mountain forest > desert shrub and woodland > irrigated farmland > alpine meadow > gobi >= cold desert. This study could provide quantitative and spatially distributed data to help water resource utilization and managements in arid and semi-arid regions of western China.