Abstract:

According to the monthly data of precipitation collected from 22 hydrographic stations of the Nanpan River basin in 31 years (1979-2009),taken standardized precipitation index（SPI）as the indicator and the period from November to the next March as the time period,the seasonal arid characteristics of the Nanpan River basin were analyzed based on the counted number of drought in recent 30 years in the time scale of five months.Moreover,the space distribution features of drought were analyzed through spatial interpolation by taking the average value of SPI in the time scale of five months from November to the next March as the indicator.The results indicated that SPI generally showed a downward trend during 30 years (1980-2009),and the meteorological drought was aggravated in annual variation;the drought became more serious in interannual variation since 1995.The meteorological drought happened across all areas to different degrees around the Nanpan River basin.In general,the degree of meteorological drought in the Nanpan River basin increased from the south to the north，and reached the worst degree in the northeast.The proportion of precipitation in the northeast was relatively small during November to the next March within one year.〖JP2〗The continuing drought from winter to spring was relatively serious in the Nanpan River basin so that the construction of water conservancy projects should be strengthened to control drought