The eastern Tibetan Plateau is subjected to strong spatial variations in precipitation, but the underlying reasons are still not well understood due to sparse in-situ meteorological observations. In this study, streamflow observations were adopted to investigate the orographic controls on precipitation in the Qingyijiang (QYJ) Basin of the eastern Tibetan Plateau. The method of multi-year annual water balance was used to estimate the basin-level precipitation using in-situ streamflow and flux-based evapotranspiration. In addition, elevation transect was designed to examine the possible links between precipitation and geomorphology. The results showed the severe under-estimation of regional precipitation by weather sites (~1150 mm yr−1
) in the QYJ Basin, where the runoff depth was as high as ~1450 mm yr−1
. The water balance revealed a much higher level of precipitation (~2000 mm yr−1
) in the QYJ Basin, but precipitation in the two adjacent basins was contrastingly low (<1000 mm yr−1
). The spatial pattern of precipitation was well consistent with the local horn-mouth geomorphology, with more precipitation occurring in the geomorphologically converging and elevating region. Furthermore, within the the QYJ Basin, annual precipitation was larger in the sub-basins (>2200 mm) on or near the bottom of the horn-mouth geomorphology than the others (<1800 mm). With these results, we concluded that the high precipitation level in the QYJ Basin could be attributed to the combined converging and lifting effects of geomorphology on the westward atmospheric vapor. Therefore, flooding risk should be carefully accounted for in the basins with similar geomorphology in the eastern Tibetan Plateau.
This is an open access article distributed under the Creative Commons Attribution License
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited