1961-2013年中国粮食主产区参考作物蒸散量时空演变特征研究

Spatial and Temporal Characteristics of Reference Crop Evapotranspiration in the Main Grain Production Area of China from 1961 to 2013

准确评估粮食主产区参考作物蒸散量(reference crop evapotranspiration,ET_0)时空变化特征,对灌区水资源优化调度、灌溉制度优化、农田水分高效利用及粮食水分生产力提高等均具有重要意义。本文基于中国粮食主产区258个气象站点逐日气象资料,采用Penman-Monteith公式计算1961—2013年参考作物蒸散量,通过Sen’s+Mann-Kendall法、累积距平法及气象倾向率等方法对其近53年时空变化趋势与特征进行分析。结果表明:近53年中国粮食主产区(全区)、温带湿润半湿润地区(Ⅰ区)、温带干旱半干旱地区(Ⅱ区)、亚热带湿润地区(Ⅲ区)及暖温带半湿润地区(Ⅳ区)ET_0年均值分别为901.90、741.89、1 077.93、940.17、847.61 mm,呈现Ⅱ>Ⅲ>全区>Ⅳ>Ⅰ区的趋势;全区及Ⅰ~Ⅳ区主要粮食作物生长季(3—10月)ET_0约占全年ET_0的87.58%、91.91%、90.05%、85.11%和83.39%;除Ⅳ(其年倾向率Y为0.002 mm/a)区外,全区及Ⅰ~Ⅲ区ET_0近53年整体呈现下降趋势,其中全区呈下降趋势的站点数达171个,占总数的61.0%,年倾斜率达到显著下降水平,其Y值为-0.288*mm/a(P<0.05);全区及各分区ET_0在20世纪90年代均呈增大趋势,其年尺度上Sen’s趋势度β全区=4.993,M-K检验值Z全区=1.978*(P<0.05),增大趋势显著,其他各年代际上趋势减小;近53年ET_0空间分布基本呈西北向东南、东北方向递减,区域性差异显著;ET_0的M-K趋势变化季节性差异显著,春季ET_0趋势自北向南增大,夏季与之相反,秋季ET_0趋势呈现中部低南北高的趋势,冬季较秋季有明显的下降趋势,整体呈现由北至南、西至东递减的趋势。

It is important to evaluate the temporal and spatial characteristics of reference crop evapotranspiration( ET_0) in the main grain producing areas,and to optimize the optimal allocation of water resources,optimize the irrigation system,improve the water use efficiency and improve the grain and water productivity. Based on the daily meteorological data from 258 meteorological stations in China's main grain-production region,the reference cropevapotranspiration from 1961 to 2013 was calculated by adopting Penman-Monteith formula,and the space-time variation during the 53 years was analyzed by Sen's + Mann-Kendall,Cumulative anomaly method and meteorological tendency rate. The results showed that ET_0 in China's main grain-production areas( the whole region),Temperate humid and semi-humid area(Ⅰ),Temperate arid and semi-arid area(Ⅱ),Subtropical humid area( Ⅲ) and Warm temperate semi-humid climate zone( Ⅳ)were 901. 90 mm,741. 89 mm,1 077. 93 mm,940. 17 mm,respectively,during the 53 years. In the whole area andⅠ-Ⅳ areas,ET_0 in main crop growing season( from March to October) accounted for 87. 58%,90. 05%,85. 11%,83. 39% of the total annual ET_0. In addition toⅣ( the yearly rate Y is 0. 002 mm/a),ET_0 in the whole region andⅠ~ Ⅲ regions presented the decreasing trend during the 53 years,and the number of sites in the whole region decreased by 171,accounting for 61. 0% of the total,the annual slope reached a significant decrease level,and its Y value was-0. 288*mm/a( P < 0. 05). In the whole area and each district,ET_0 showed an increasing trend in1990 s,the β whole = 4. 993,Z whole = 1. 978*( P < 0. 05). The trend of increase in 1990 s was significant,but it decreased in other years. the spatial distribution of ET_0 in the past 53 years was basically decreasing from northwest to northeast and northeast,and the regional difference was significant. The seasonal variation of the M-K trend of ET_0 was significant,and the trend of ET_0 in spring was increasing from north to south,and the trend was opposite in summer. The trend of ET_0 in autumn was the trend of middle and low northsouth. In autumn,ET_0 showed lower central and higher north-south trend,while winter had a decreasing trend compared with autumn,the overall trend was decreasing from North to South and West to East.