中文摘要：

根据黑河流域中游地区7个气象站点1967年-2009年的逐日气象资料,利用FAOPenman-Monteith模型和所提供的作物系数计算出主要作物不同生育阶段的需水量,采用Mann-Kendall趋势分析法对主要作物需水量的变化特征进行了研究,并对引起作物需水量的驱动因子进行了相关性分析,在此基础上,应用基于分型理论的R/S方法对作物需水量的变化趋势进行了预测。结果表明：近43年来,中游地区春小麦和玉米ETc均呈波动下降趋势,春小麦下降斜率为6mm/10a,玉米下降斜率为8mm/10a;其中,民乐和甘州站春小麦和玉米的ETc呈缓慢上升趋势,其他站点春小麦和玉米的ETc均呈下降趋势,且部分站点下降趋势显著。春小麦和玉米ETc的主要影响因子均为相对湿度、日照时数和平均风速。中游地区各站点春小麦和玉米需水量Hurst指数H均大于0.5,同时分维数D均小于1.5,因此未来一段时间ETc仍然保持与过去相一致的变化趋势。

英文摘要：

The Heihe River Basin, located in the arid area of northwestern China, is the second largest Inland River Basin. In recent years, with the increase of the agricultural water in the middle reaches of the Heihe River Basin, the conflicts between agricultural water and ecological water as well as water use in the middle and lower reaches are becoming more and more severe. Because irrigation water is the main aspect of agricultural water use, the situation of water supply and demand and the tendency of water resources used by irrigation have been drawing more and more attentions. Water requirement of crops is an important condition for irrigation scheduling, water resources planning and future decision-making. Understanding the water demand and consumption of staple crops comprehensively has very important significance for the development of water-saving agriculture, the intensive management of water resources, the improvement of water use efficiency and the simulation and prediction of crop yield. In this paper, according to the weather data of 7 meteorological stations in the middle reaches of Heihe River Basin, the water requirement of main crops in different growth stages were calculated by using FAO Penman-Monteith model and crop coefficient. Besides, the variation characteristics and the major climate influence factors of the water requirement of main crops were analyzed respectively by using the Mann-Kendall trend and correlation analysis method. Then, based on the above analysis, the future trends of crop water requirement were forecast by the method of rescaled range analysis. The results show that the ET c of both spring wheat and maize exhibit fluctuating decrease trend in the middle reaches of Heihe River Basin with ET c of spring wheat declines at a rate of about 6mm/ 10a and maize at a rate of about 8mm/10a. As to the stages of development, the ET c of spring wheat exhibit a slightly increasing trend at crop development stage and late stage while the ET c of maize exhibit a decreasing trend at all stage