The water requirement was obtained by regression analysis between rainfall and separated climate yield,to evaluate the water complacent extent,Crop yields decreased in stronger El-Nio year and changed with occurring time in weaker El-Nio year.

Based on data of winter wheat yield and climate data of winter wheat region in Hebei province, by using improved separation method of climate yield from actual yield, quantitative analysis were conducted about impacts of climate warming on winter wheat yield.

Then by analysing the relationship between crop climatic yield and precipitation we obtained the water requirement index in different growth durations.

Climate vulnerability of autumn grain crops in rainfed farming areas of Gansu Province;