Abstract:

Analysis on the distribution characteristics of precipitation in a year is of great importance for taking precautions against and fighting natural adversities as well as water resources management on the north slope of the Dabie Mountain.Using the daily precipitation data of 6 meteorological stations in Lu’an city from 1956 to 2010,the spatial and temporal distribution characteristics of annual precipitation concentration were analyzed based on the definitions of Precipitation Concentration Degree(PCD) and Precipitation Concentration Period(PCP).The results showed that the average PCD in Lu’an was 0.37 and the average PCP was the 37~38 pentad. The annual precipitation decreased gradually from southwest to northeast in spatial distribution,while the PCD and the PCP increased from south to north.The trend of annual precipitation was not obvious, but PCD and rainy season precipitation exhibited increasing tendency at the 010 significance level.It could lead to increasing risk of floods in rainy season in Lu’an city. The jumps in the annual precipitation occurred in 1972,1990 and an abrupt change occurred in 1972 in the PCD process.It is found that the annual amount of precipitation has significant positive correlation with PCD,that is to say the much(less) is the annual precipitation,the bigger (smaller) is the PCD.It is also found that when rainy season precipitation is extremely excessive and the PCD is much bigger than the average,Lu’an city is vulnerable to flood,otherwise to drought