亚洲一区欧美在线,日韩欧美视频免费观看,色戒的三场床戏分别是在几段,欧美日韩国产在线人成

Due to the influence of agricultural production activities and precipitation changes in Hebei Province, the social water use and water resource carrying capacity in Hebei Plain was seriously unbalanced. Based on the regional water resource condition and Penman-Monteith formula, the water consumption and irrigation water demand of staple crops were estimated and the effect of planting structure change on the water irrigation amount in Hebei Province was evaluated. Results showed that the total water resources, surface water resources and groundwater resources in Hebei Province during 2001—2017 were decreased by 22.36%, 42.15% and 9.01% with respect to the averages of the past 62 years (i.e. 1956—2017), respectively. Although the groundwater extraction and farmland irrigation amount displayed a slight decline trend, the groundwater overdraft still reached up to 3.31 billion m3, together with the groundwater table reached 60.34~70.46 m in the typical groundwater funnel area. Compared with that shown in 1980, the planting area of the staple crops was increased by 21.68% in 2017. The water requirement in the crop growing season for all of the text crops showed a decline trend, with the order from high to low to be vegetable (750.56~893.09mm), rice (698.25~832.60mm), fruit (653.93~773.28mm), cotton (506.30~634.23mm), potato (481.42~594.37mm), winter wheat (401.66~504.60mm), oil crops (406.26~510.68mm), soybean (335.28~429.74mm), maize (309.72~399.54mm) and millet (269.94~345.77mm). The water deficit index of winter wheat was the highest among all crops (0.72), followed by vegetables (0.47), rice (0.46) and fruit (0.36). The annual irrigation water of winter wheat, vegetable and fruit accounted for 46.87%, 12.94% and 12.24% of the total crop irrigation amount. Compared with that of 1980—1989, the planting area of vegetable and fruit was increased by 186.01% and 59.98% from 2010 to 2017, respectively. Correspondingly, the water demand of vegetable and fruit was increased by 143.75% and 18.91% whereas the water demand of other crops was decreased by 3.34%~91.57%. The increasing planting area of vegetable and fruit resulted in the elevated amount of agricultural irrigation water. It was suggested to reduce the planting proportion of high water consumption crops, such as vegetable and fruit meanwhile to sustain the field crop cropping index by decreasing the planting scale of winter wheat-summer maize rotation. Moreover, these practices were benefit to balance the staple food’s supply and demand, sustainable water resource and help the national food security. Scenario analysis showed that the planting area of vegetable and fruit should be decreased to 1.72×105hm2 and 1.97×105hm2, which could meet the market demand of Beijing-Tianjin-Hebei Plain and reduce the irrigation demand amount of 3.31 billion m3 in this ecological region.