Temporal and spatial variations of delta super(18)O in precipitation of the Yarlung Zangbo River Basin

This paper reveals the temporal and spatial variations of stable isotope in precipitation of the Yarlung Zangbo River Basin based on the variations of delta super(18)O in precipitation at four stations (Lhaze, Nugesha, Yangcun and Nuxia) in 2005. The results show that delta super(18)O of precipitation has distinct seasonal changes in the Yarlung Zangbo River Basin. The higher value of delta super(18)O occurs in spring prior to monsoon precipitation, and the lower value occurs during monsoon precipitation. From the spatial variations, with the altitude-effect and rainout process during moisture transport along the Yarlung Zangbo River Valley, super(18)O of precipitation is gradually depleted. Thus, delta super(18)O of precipitation decreases gradually from the downstream to the upstream, and the lapse rate of delta super(18)O in precipitation is approximately 0.34ppt/100m and 0.7ppt/100km for the two reasons. During monsoon precipitation, spatial variation of delta super(18)O in precipitation is dominated by the amount effect in the large scale synoptic condition.