CR 67:257-269 (2016)  -  DOI: https://doi.org/10.3354/cr01361

ABSTRACT: Precipitation in a typical basin of the Qiantang River, which is a vital component of the freshwater supply of Zhejiang province, eastern China, was analyzed for spatial and temporal changes from 1960-2006, based on daily precipitation measured at 14 meteorological stations. Although regional annual precipitation did not reveal any significant trends, distinct inter-decadal variation was identified when an integrated precipitation indicator was applied. Trends in annual precipitation with different magnitudes and their corresponding frequencies were characterized by different spatial distribution patterns. Analysis of extreme precipitation events indicated more extreme precipitation after the mid-1980s, which is consistent with the results of a dry/wet condition analysis. Both the significant increase in summer precipitation and the transition from a consecutive dry period to a relatively wet period after the mid-1970s suggest that this region is becoming wetter and may be prone to more floods during the summer. The variation in summer precipitation was largely captured by an empirical orthogonal functions (EOF) analysis, and the similar variation in the first principal component proved the applicability and effectiveness of the EOF analysis. Regional factors, such as aerosols, land reclamation and the extent of irrigation, combined with large scale circulation may have influenced the observed change in precipitation. This research provides insight into historical change in precipitation, and will aid in future disaster forecasting/warning.

KEY WORDS: Extreme precipitation · Summer precipitation · Spatio-temporal variation