农业发展对东北地区参考作物蒸散发量变化趋势的影响

Effects of Agricultural Development on the Trends in Reference Evapotranspiration over Northeast China

为了确定东北地区参考作物蒸散发量ET_(0)的历史变化趋势是否受到了农业发展的影响,为农业水资源高效利用提供支撑。利用东北地区109个气象站1961-2017年日气象数据计算参考作物蒸散发量,并确定全年、生长季(5-9月)和非生长季(10-4月)的变化趋势。利用站点周围5 km半径范围内耕地面积比例(CF)作为衡量农业活动影响大小的指标,分析ET_(0)及其辐射项(ET_(rad))和空气动力学项(ET_(aero))变化趋势值大小与耕地面积比例指标之间的关联,并对比不同类型站点ET_(0)的变化。结果表明:东北地区气象站观测到的ET_(0)1961-2017年变化趋势值与站点周围5 km半径范围内耕地面积比例CF值具有显著负相关关系,CF值越大,ET_(0)下降的趋势越显著。ET_(rad)总体呈增加趋势,与站点CF值没有相关性。ET_(0)的显著下降主要来自于ET_(aero)。ET_(0)和ET_(aero)变化的趋势值与CF值之间的相关性在作物生长季更为显著;CF>60%的33个站点平均的生长季ET_(0)和ET_(aero)与CF<15%的18个站点的差值在1961-2017年间持续增长,与农业发展具有一定的一致性。农业发展通过空气动力学项加快了东北地区1961-2017年ET_(0)的下降趋势,在农业用水管理中应该考虑这种影响。

In order to determine whether the historical variation trend of reference crop evapotranspiration(ET_(0))in Northeast China was affected by agricultural development and to provide support for the efficient utilization of agricultural water resources,daily meteorological data of 109 meteorological stations in Northeast China from 1961 to 2017 were used to calculate the reference crop evapotranspiration.The change trends of ET_(0),as well as its radiation and aerodynamic components(ET_(rad) and ET_(aero))of the whole year,the growth season(May to September)and the non-growth season(October to April)were calculated.The proportion of cultivated land area(CF)within a radius of 5 km around the meteorological station was used as an indicator to measure the impact of agricultural activities.The correlation between the variation trend value of ET_(0) and its radiation item(ET_(rad))and aerodynamics item(ET_(aero))and the proportion of cultivated land area was analyzed,and the change of ET_(0) in different types of sites was compared.The results showed that there was a significant negative correlation between the ET_(0) variation trend observed by meteorological stations in Northeast China from 1961 to 2017 and the CF value of cultivated land area ratio within a radius of 5 km around the stations.The larger the CF value was,the more significant the decreasing trend of ET_(0) will be.ET_(rad) showed an overall increasing trend and was not correlated with the CF value of the site.The significant decrease in ET_(0) was mainly attributed to ET_(aero).The correlation between the trend value of ET_(0) and ET_(aero) and CF value was more significant in the crop growing season.Compared to the 18 stations with CF<15%,the 33 stations with CF>60%were characterized with mores significant decreasing in ET_(0) and ET_(aero),especially in the growth season.Their differences were consistent with the agricultural development in Northeast China.The more significant decreasing in ET_(0) in the agricultural regions over Northeast China can be attributed to the agricultural development and thus should be considered in agricultural water management.