During the landfall of Typhoon Billis in July 2006, Wujiang River, a tributary of the Beijiang River basin, was hit by an unusual rainstorm in history, resulting in the largest flood ever recorded in the basin. Based on precipitation record and Doppler weather radar data, it is found that the "train effect" induced by a convective storm, which originated in southern Hunan and crossed the divide, is the main reason for the extreme precipitation in Wujiang River basin. The study of the convective storm activity by using GIS technology shows that the complex topography of Wujiang River basin changed the direction of the convective storm several times, which greatly prolongs the duration of the storm in Lechang city, resulting in local rainstorm and flash flood. The study also found that the Huangcen Reservoir in Qitianling Mountain area was affected by typhoon, which probably enhanced local convections. The study reveals the influence of mesoscale and miso-scale topography on typhoon rainstorm, which contribute to the prevention of typhoon-induced disasters.

multi-scale topography  /  Wujiang River  /  ‘06.7’ typhoon rainstorm  /  influence