黄河下游大型引黄灌区蒸散发长期变化特性

采用生态水文模型模拟黄河下游大型引黄灌区———位山灌区1984—2006年的水量平衡过程,分析蒸散发量的长期变化规律。结果表明:位山灌区多年平均蒸散发量为596mm,占降雨和灌溉总量的82%;小麦和玉米生长期内多年平均蒸散发量分别为284mm和314mm,分别占降雨和灌溉总量的99%和71%;降雨量的年际变异性较大,但受灌溉的影响蒸散发量的年际变异性较小,且无显著的时间变化趋势;作物主要生长期内蒸散发量的年际变化主要与潜在蒸发量有关;蒸散发量的季节变化主要受潜在蒸发量和作物生长过程的控制。

Long-term variability of evapotranspiration in a large irrigated area in lower reach of Yellow River

The process of water balance in Weishan Irrigation District during the period from 1984 to 2006,a large irrigation district in the lower reach of Yellow River,is simulated by means of the ecohydrological model.The long-term variability of its evapotranspiration(ET) is analyzed.The results show that the annual mean ET is 596 mm and accounts for 82% of the total amount of precipitation and irrigation.The mean annual ET of wheat and maize during their growing periods is 284 and 314 mm,respectively,and accounts for 99% and 71% of the total amount of precipitation and irrigation,respectively.The inter-annual variability of the precipitation is dramatic.However,the inter-annual variability of ET is small and has no significant temporal trend owing to the influence of the irrigation.The inter-annual variation of ET of the crops during their main growing periods mainly relates to the potential evaporation.The seasonal variation of their ET is mainly controlled by the potential evaporation and the growth of the crops.