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Title: Trends and variability of daily precipitation extremes during 1960-2012 in the Yangtze River Basin, China

Author
item GUAN, YINGHUI - China Institute Of Water Resources
item ZHENG, FENLI - China Institute Of Water Resources
item Zhang, Xunchang
item WANG, BIN - Beijing Forestry University

Submitted to: International Journal of Climatology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2016
Publication Date: 5/23/2016
Citation: Guan, Y., Zheng, F., Zhang, X.J., Wang, B. 2016. Trends and variability of daily precipitation extremes during 1960-2012 in the Yangtze River Basin, China. International Journal of Climatology. Doi: 10.1002/joc.4776.

Interpretive Summary: Trends and variability of extreme precipitation events are important for water-related disaster prevention and mitigation as well as water resource management. Based on daily precipitation dataset from 143 meteorological stations in the Yangtze River Basin (YRB), a suite of precipitation indices were used to study spatial distribution and temporal variations of precipitation extremes during 1960–2012. Results showed that total precipitation amount did not show any significant trend for the whole YRB against the large interannual and interdecadal variability of precipitation. However, simple daily intensity index, very wet day precipitation, extremely wet day precipitation, extremely heavy precipitation days, maximum 1-day precipitation, maximum 5-day precipitation and maximum consecutive dry days all increased significantly in YRB. In contrast, the weak precipitation days and maximum consecutive wet days decreased significantly. The correlation analysis between trend magnitudes in precipitation indices and latitude as well as elevation showed that in a majority of cases, precipitation variation trends had an insignificant relationship with latitude and elevation when elevation is above 500m, but a significant negative correlation with elevation when elevation is below 500 m. The results should be useful for hydrologists and soil conservationists to develop mitigation plans for flooding and erosion control.

Technical Abstract: Trends and variability of extreme precipitation events are important for water-related disaster prevention and mitigation as well as water resource management. Based on daily precipitation dataset from 143 meteorological stations in the Yangtze River Basin (YRB), a suite of precipitation indices recommended by the Expert Team on Climate Change Detection and Indices, which has not been applied in this region, were used to run a preliminary investigation in spatial distribution and temporal variations of precipitation extremes during 1960–2012. Results showed that total precipitation amount did not show any significant trend for the whole YRB against the large interannual and interdecadal variability of precipitation. However, simple daily intensity index, very wet day precipitation, extremely wet day precipitation, extremely heavy precipitation days, maximum 1-day precipitation, maximum 5-day precipitation and maximum consecutive dry days all increased significantly in YRB. In contrast, the weak precipitation days and maximum consecutive wet days decreased significantly. This implied that the precipitation processes in the YRB were dominated by precipitation events with shorter durations. Geographically, a wetting tendency was observed in the eastern Tibet Plateau and the middle and lower YRB, while the other regions had experienced precipitation deficits, corresponding to drought. The increasing precipitation was mainly due to the intensification of heavy precipitation events, and the decreasing precipitation may be attributed to the decrease of weak or moderate precipitation events. In addition, the regional trends were of greater magnitude in the middle and lower YRB, indicating more frequent extreme precipitation events in the region. Time series analysis revealed that most precipitation indices exhibited neither a stable nor a gradual pattern during 1960–2012, but a clearly upward trend though non-monotonous since the late-1980s was evident. The correlation analysis between trend magnitudes in precipitation indices and latitude as well as elevation showed that in a majority of cases, precipitation variation trends had an insignificant relationship with latitude and elevation when elevation is above 500m, but a significant negative correlation with elevation when elevation is below 500 m.