Abstract: By using the precipitation data of meteorological stations in the Xijiang River basin, and time series of the flood peak water levels of the mainstream and tributaries of the Xijiang River in 1959-2008, the data sets of yearly flood occurrence times were developed, and the spatial and temporal characteristics of the flood occurrence times and their evolution laws were analyzed. The results indicate that the flood frequency in the mainstream region of the Xijiang River was higher than those in the tributary regions, and the flood frequency in the lower reaches of the tributaries was higher than that in the upper reaches. The flood occurrence times had a prominent stage characteristic and some significant abrupt changes, the main abrupt changes happened in 1967 and 1993. Moreover, the floods occurred more frequently in recent 15 years; the basin-wide disastrous floods mainly concentrated in this period. Studying the flood laws in the Xijiang River basin is beneficial for raising the level of flood disaster evaluation and prediction, and for providing a scientific basis for hazard mitigation and prevention.

Key words: flood frequency, spatial and temporal characteristic, evolution law, stage characteristic, abrupt change