柳园口灌区参考作物腾发量的长期变化趋势及其对灌溉需水量的影响

Long-term Trend of Reference Evapotranspiration in Liuyuankou Irrigation System and its Impacts on Irrigation Water Requirements

研究该文的目的在于揭示了柳园口灌区参考作物腾发量的长期变化规律,阐明其产生原因及可能产生的影响,为应对气候变化对农业生产带来的负面影响提供基础。采用FAO-56推荐的Pen-man-Monteith公式计算河南省柳园口灌区1983—2003年的逐日参考作物腾发量,用Mann-Kendall检验对灌区的参考作物发量进行长期变化趋势分析,对参考作物腾发量的长期变化趋势及其与气象因素、灌溉引水量的关系进行了分析。结果表明,在过去的20多年中,ET0呈极显著的下降趋势,其下降的幅度约为50mm/10年;导致ET0下降的主要原因是日照时数下降,其次是风速的下降,气温升高并不足以抵消日照时数和风速的下降而使ET0上升;ET0的下降主要出现在4月和6—8月。在降雨量变化不明显的情况下,灌溉季节的ET0的下降使灌区的灌溉需水量呈下降趋势,而灌区近年来的引黄水量减少也证明了这一事实。因此,除了节水灌溉技术的推广,气候变化使灌溉需水量减少,灌区的节水也有气候变化的"贡献"。

The long-term trend of reference evapotranspiration （ET0） and it＇ s relationships with weather parameters and irrigation water use were analyzed, and the reasons and impacts of ET0 trend were investigated. Daily meteorological data for the years of 1983-2003 of Liuyuankou Irrigation Area, Henan Province from Huibei Irrigation Experiment Station were collected, then daily, monthly and annual ET0 were calculated using the FAO-56 Penman-Montieth model. Mann-Kendall tests were conducted to detect trends in ET0 and corresponding meteorological parameters. The results show that in Liuyuankou Irrigation System, ETo decreased 50mm/a in the last two decades; decreasing ET0 was caused mainly by decreasing sunshine hour firstly and wind speed secondly, increasing air temperature was not enough to counteract the impacts of the former two; annual ET0 decrease was contributed by decrease in April, June, July and August; when there was no significant trend in rainfall, decreasing ET0 resulted in decreasing trend in irrigation requirement, which was confirmed by reduced diverted irrigation water from Yellow River. Therefore, besides dissemination of water-saving irrigation techniques, reduced diverted irrigation water from Yellow River was partially contributed from the decreasing irrigation water requirements due to climate change.