Abstract:

The grain crops was seriously influenced by drought disaster in Tianhusi. Based on the precipitation data from 1961 to 2010 in seven weather stations which located in Tianshui and grain yield from 2001 to 2010 in seven counties, the model of drought risk index for assessing drought disaster had been set up and the drought risk of wheat and maize had been analyzed. The results showed that the light drought appeared 7.09 times a year, the middle drought appeared 2.52 times a year, heavy drought appeared 0.5 times a year and the heaviest drought appeared 0.25 times a year. The frequency of drought was higher in spring, next in early summer and hot summer, lower in early autumn. The light, heavy and the heaviest drought occurred frequently in the north of Wei river and middle drought appeared frequently in the basin of Xi and Wei river. The light and middle drought risk indexes were higher and heavy and the heaviest drought risk indexes were lower for wheat. The light drought risk index of maize was higher and followed by middle drought. The heavy and the heaviest drought had little effect for growth of maize. The drought risk index of wheat was higher in spring and that of maize was higher in early autumn. The drought risk index of wheat was higher in the whole growth period in the north of Wei river and drought risk index of maize was higher in the whole growth period in basin of Xi and Wei river, Qian and Qingshui counties. The drought risk index of wheat was higher than that of maize and the autumn crops had advantages of climate resource compared with summer crops in Tianshui.