Index System and Influence of Drought in Northwest China

In this paper, the index systems of the agricultura drought and decrease percentage of grain crop are established. Th trend and influence of drought in the region is analyzed based o the 50 years (1951-2000) statistical data of precipitation and 5 years (1951–2002) agricultural drought of the region, includin five provinces: Shaanxi, Gansu, Ningxia, Qinghai and Xinjiang The result shows that the drought disaster is increasing and th most serious were in the 1970s and 1990s, and main agricultura drought is a great disaster incident. The regression prediction equa tion of drought and flood grades and agricultural drought area grades are set up by the harmonic wave method, and forecastin the drought will lighten during the first ten years of the 21s century.

In this paper, the index systems of the agricultural drought and decrease percentage of grain crop are established. The trend and influence of drought in the region is analyzed based on the 50 years （1951-2000） statistical data of precipitation and 52 years （1951 2002） agricultural drought of the region, including tire provinces： Shaanxi, Gansu, Ningxia, Qinghai and Xinjiang. The result shows that the drought disaster is increasing and the most serious were in the 1970s and 1990s, and main agricultural drought is a great disaster incident. The regression prediction equation of drought and flood grades and agricultural drought areas grades are set up by the harmonic wave method, and forecasting the drought will lighten during the first ten years of the 21st century.