Climatic hazards to the agricultural potential in the North China plain

Abstract

Spring drought and summer flood and drought pose continuous threats to crop production in the North China Plain. High moisture stress during the spring is shown by the low ratios of actual evapotranspiration ( ET) to potential evapotranspiration ( PE). Uneven precipitation distribution, together with the low preseasonal soil moisture storage, is responsible for spring drought. Precipitation probability analysis for the months of May and June indicates only a 10–30% chance of an adequate moisture supply in this region during spring. Variability of precipitation amount and intensity share the responsibility for summer flood and drought. Precipitation probability alone for the months of July and August indicates that, on the average, the North China Plain has only a 30–50% chance of adequate moisture for crop growth. However, the probability of an optimum amount of precipitation decreases considerably when rain intensity is taken into consideration. Near the two centers of maximum intensity, in July and August, rainfall reaches 22–25 mm per rainy day. By comparison, growing-season precipitation in the winter wheat region of the Great Plains of the U.S.A. is less intense and more evenly distributed.