海河流域参考作物腾发量长期变化趋势分析

Analysis of Long-term Trends in Reference Crop Evapotranspiration in Haihe Basin

收集了海河流域37个国家气象站的逐日气象资料,采用FAO-56 Penman-Monteith方法计算参考作物腾发量(ET0);采用Mann-Kendall法进行趋势检验。通过分析及各气象因素的变化趋势,揭示了气候变化对参考作物腾发量长期变化规律及对作物灌溉供需水量可能产生的影响。结果表明:自20世纪50年代至2007年末,在海河流域下游地区具有较明显的ET0下降趋势,而在各主要河流的上游地区则有明显的上升趋势;其原因是整个流域内呈现气温上升相对湿度下降趋势,风速和日照时数都有下降趋势,但在上游地区前者占主导地位,而在下游地区后者占主导地位;在整个流域降雨呈现下降趋势的情况下,ET0上升使上游地区灌溉需水量增加,而在下游地区作物生长也可能受影响;除了工业和居民用水快速增长外,气候变化也是导致近几十年来海河流域水资源紧缺的原因之一。

Daily weather data for 37 national meteorologic stations in the Haihe Basin were collected, and the FAO56 method was employed to calculate reference crop evapotranspiration （ET0）. Long-term trends in ET0 and related meteorologic parameters were detected using Mann-Kendall test. Finally the impacts of climate change on variations of ETo and possible responses in crop irrigation requirements were investigated. The results show that there was a decreasing trend in ETo in the Lower Haihe Basin, as a contrast, increased ET0 was detected in the upstream areas of the main rivers from 1950s to 2007; even in the whole basin, increased temperature and decreased relative humidity companioned with decreased wind speed and sunshine duration, while the former played a dominant role in the lower areas and the later in the upper; the rising ET0 increased irrigation water requirement in the upper areas when precipitation declined and crop development might also be negatively impacted by dropping ET0 ; besides the alarmingly rise in industrial and domestic water requirements, climate change also contributed to the water stress in last decades.