Weather complexions causing diluvial rains in Thua Thien Hue province in 2020

Abstract

Based on meteorological and hydrological data series analysis and general geographical analysis, we evaluated the impact and role of weather patterns in the formation of rain and flood in Thua Thien Hue province. The results show eight primary combinations of weather patterns that caused rain and flood from 1981 to 2020. Cold air combined with storms or tropical depressions caused rain and produced the most floods (20.7%), followed by storm formation or tropical depression (18.6%) and cold air combined with high easterly winds (14.5%). Most of the significant floods occurring in Thua Thien Hue province were mainly due to the combined weather patterns causing heavy rains on a large scale. In 2020, six weather patterns caused rain and floods. In particular, the historic flood peak on October 9 resulted from a phenomenon called "floods and more floods" when a combination of four weather patterns (intensified cold air, tropical convergence band, high-altitude easterly wind development, and storm rain bands) appeared simultaneously, causing continuous and prolonged heavy rains and hence the water level on rivers to rise rapidly and remain at a high level. The results of this study are the basis for warning flood risks, serving the planning and socio-economic development of the locality.