Analysis on Precipitation Behaviors and Droughts & Floods Over the Past 51 Years in the Yangtze River Delta

To learn about the changing trend of water resources quantity in the Yangtze River Delta, make rational allocation of water resources, and prevent regional drought & flood risks, the spatial and temporal distribution characteristics of precipitation and drought & flood in the Yangtze River Delta were investigated. Sliding average method, standardized precipitation index method (SPI), and inverse distance weighted interpolation method (IDW) etc. were used to analyze the hydrologic characteristics of YRD based on the daily precipitation data from 15 national meteorological stations in the Yangtze River Delta during the period from 1960 to 2010. According to the result: (1) The Yangtze Delta exhibited a gradually increasing trend of annual precipitation, while the flood frequency has been higher than drought frequency over the past 51 years; (2) At the Yangtze Delta, the maximum mean precipitation was normally observed in June, the minimum mean precipitation in December, the highest flood frequency in April and July, and the highest drought frequency in March; (3) The precipitation gradually increased from north to south at the Yangtze Delta, spatially, the precipitation was more evenly distributed in the north than in the south; the flood prone area was larger than drought prone area at the Yangtze Delta with West Hangzhou, East Shaoxing and West Ningbo susceptible to both drought and flood.1