Spatial and temporal distributions of trends in climate extremes of the Feilaixia catchment in the upstream area of the Beijiang River Basin, South China



To evaluate the changes in extreme climatic events in the Feilaixia catchment in South China, the spatial and temporal distributions of extreme climate indices trends during 1969–2011 were investigated. With quality control and homogeneity assessment, daily maximum and minimum surface air temperature from 11 meteorological stations and daily precipitation from 24 rainfall stations were used. Eight indices of extreme temperature and six indices of extreme precipitation were chosen. Trends were calculated using Sen's slope estimator. Statistical significance of trends was checked with the Mann–Kendall method. High correlations were found between the mean annual temperature and temperature extremes, as well as between the annual total precipitation and precipitation extremes in most cases. The analyses of extreme temperature indices detected significant and stable trends in the majority of the stations. The strongly stable downward trends in cold extremes and the strongly stable upward trends in hot extremes were recorded in the whole region, except for in some small areas primarily located in the central part of the region. In contrast, significant and stable positive trends were sporadically recorded for precipitation extremes in the study area during 1969–2011, which predominantly occurred in the northern part of the region. Furthermore, the positive trends were much more frequent than the negative trends in most extreme precipitation indices. There were significant and stable trends recorded in most of the average temperature extremes, whereas insignificant and unstable trends were found for most of the average precipitation extremes.