Spatial and temporal analysis of drought risk during the crop-growing season over northeast China

Northeast China as an important agricultural zone for commercial and economic crop in China suffered from increased drought risk that seriously threatened agricultural production and food security in recent decades. Based on precipitation datasets from 71 stations from 1960 to 2009 and on the reliable statistical methods of the Mann-Kendall test, Sen's slope and the Standardized Precipitation Index, we analyzed the temporal and spatial variation of drought occurrence during the crop-growing season (from May to September) and summer (from June to August). The results showed that regional mean precipitation during the crop-growing season and summer over the last 40 years has decreased at the rate of -1.72 and -1.12 mm/year, respectively. According to timescale analysis of abrupt changes, there were two distinct time series (1965-1983 and 1996-2009) with decreasing precipitation trends at a 95 % confidence level. A comparison between the two time series of these two periods demonstrated that more frequent and more severe drought occurred during 1996-2009. Furthermore, drought risk in recent decades has become even more serious both in severity and in extent. Especially in the crop-growing season of 2001 and summer of 2007, over 25 % (2.0 x 10(5) km(2)) of study area experienced severe drought (serious and extreme droughts). Our results highlight the urgent need for the development of effective drought adaptations for cropland over northeast China.