Hydrothermal change in winter wheat-producing area in Northern Anhui of China and its impact on winter wheat production

摘要

Generally speaking, in the context of global climate change, the water shortage in northern Anhui winter wheat-producing area will become increasingly serious. The current winter wheat high-yield heavily depended on groundwater irrigation which is not sustainable. Therefore, water interception and storage of the flood season precipitation should be considered from strategic perspectives to solve the water supply problem for winter wheat irrigation. In this article we evaluated the temperature, evaporation, precipitation and other data in various historical periods from major weather stations of main winter wheat –producing area in northern Anhui to study the variation trends of precipitation, evaporation and dryness in winter wheat growing season. We also analyzed their impact on winter wheat production. Our results showed that the northern Anhui area is sensitive to the global weather change and the temperature variation in synchronization with the general trend of global warming. The temperature has raised about 1.8 oC since the 1950s of last century, which is higher than the global average increase. In accordance to the temperature rise, evaporation was increased 3 to 5%, with a maximum in February and May. There was no significant change in precipitation in the area, but the non-uniformity of precipitation was enhanced and the proportion of short-term heavy rains tended to increase in the annual precipitation. 24 h maximum rainfall usually accounted for 10 to 30% and the process (storm) precipitation for more than 50% of annual precipitation, with hourly rainfall reaching up to 80 mm or over. The rainfalls per unit time during heavy precipitation are far more than most soil absorption rates. Most precipitations are lost in the form of runoffs and can not effectively replenish soil water and large runoff formations result in a large number of local floods. In total, the uneven rainfall and increased evaporation led to water shortage in this agricultural area which was detrimental to winter wheat production.