干湿状况主要决定于降水与蒸发。河北省年蒸发量一般在620～1000毫米之间,最小值在坝上东部,最大值在东南部平原。一年中以夏季蒸发量最大,占全年的46％,春季占33%,秋季占16%,冬季最小占全年的5％。 以年蒸发量与降水量的比值——年干燥度,来表征我省的干湿状况,可划分为较湿润(年干燥度<1.3)、半湿润(1.3～1.5)、半干旱 Wet and dry conditions mainly depend on precipitation and evaporation. Annual evapotranspiration in Hebei Province is generally between 620 to 1000 mm, the minimum in the dam east, the maximum in the southeast plains. In one year, summer evaporation is the largest, accounting for 46% of the whole year, accounting for 33% in spring, 16% in autumn and 5% in winter. The ratio of annual evaporation and precipitation - annual dryness, to characterize the province’s wet and dry conditions can be divided into more humid (annual dryness <1.3), semi-humid (1.3 ~ 1.5), semi-arid