Abstract:

Based on the yearly and monthly precipitation data (1955-2009) of Datong, using a meteorological drought index as atmospheric percentage, the author analyzed the meteorological drought occurring year in Datong, time evolution and the impact on agriculture. The results showed the annual precipitation decreased by 8.6 mm/10a in 55 years, meanwhile, there were 20 dry years in total, and the drought frequency was 36%, which meant that there was a drought year every 2.8 years. The frequency of dry season were 32.7% in spring, 30.9% in winter, 25.4% in autumn and 21.8% in summer. Severe winter drought years was the most, followed by summer, but severe spring and autumn drought years were less. The humid autumn trend was not apparent; spring, summer and winter drought which were increasing, resulting in enhanced drought general trend in Datong. The author analyzed the precipitation in the key period of crops (April to September), since 1980 the overall bias by the floods to partial drought in Datong. The frequency of the annual and quarterly drought pointed to the evident raise of the drought frequency during 1980s. And it reached its extreme value in 1990s. Combining the agricultural drought data, the author further analyzed the influence of meteorological drought on agriculture, and put forward some countermeasures and suggestions, expecting to have positive guidance for the local drought control.