气候变化对汾西灌区灌溉用水量的影响研究

Impact of Climate Warming on Irrigation Water in Fenxi Irrigation Area

研究灌区气象要素长期变化特征及其对灌溉用水量的影响对掌握灌区灌溉用水规律从而进行更科学合理的灌溉具有一定的指导意义和实际参考价值。基于山西汾西灌区3个气象站点1975-2018年的实测气象资料,采用线性倾向估计、M-K检验等方法分析降水和气温的时间变化特征,用作物系数法计算灌区作物需水量和灌溉用水量,综合分析气候变化对灌溉用水量的影响,建立了不同水文典型年降水、作物需水量与灌溉用水量之间的关系。结果表明:44 a来汾西灌区降水量以2.7 mm/10a的速率下降,在1977年第一次突变;平均气温以0.471℃/10a的速率显著上升,在1997年突变;灌区气候向暖干方向发展,灌溉用水量以25.4 mm/10a的速率上升。气温突变伴随着降水骤降为多年最低值,灌溉用水量比多年均值增加了396.8 mm,远大于降水突变年。作物需水量增加1 mm,灌溉用水量就会增加1.92 mm;降水增多,其对灌溉用水的影响减小,单位降水量在丰、平、枯水年可分别引起1.29、1.74、2.72单位灌溉用水量的变化,枯水年的灌溉定额比丰、平水年多出20%。

Studying the long-term variation characteristics of meteorological elements in irrigated areas and their influence on irrigation water consumption has significant guiding and practical value for understanding the patterns of irrigation water in irrigated areas so as to carry out more scientific and efficient irrigation practices.Based on the measured meteorological data of three meteorological stations in Fenxi Irrigation District,Shanxi Province spanning the period from 1975 to 2018,this paper analyzes the temporal variation characteristics of precipitation and temperature by linear tendency estimation and M-K test,calculates crop water demand and irrigation water consumption in irrigated area by crop coefficient method,comprehensively analyzes the impact of climate change on irrigation water consumption,and establishes the relationship between typical annual precipitation,crop water demand and irrigation water consumption in different hydrological typical years.The results show that the precipitation in Fenxi irrigation area decreased at a rate of 2.7 mm/10a and the first mutation occurred in 1977,the average temperature increased significantly at a rate of 0.471°C/10a,and abruptly changed in 1997,in the past 44 years.The climate of the irrigation area is developing in the direction of warm and dry,and the irrigation water consumption increases at a rate of 25.4 mm/10a.The sudden change in temperature was accompanied by a sharp drop in precipitation to the lowest value in many years,and the irrigation water consumption increased by 396.8 mm compared with the multi-year average,which was much greater than the year when precipitation suddenly changed.The irrigation water consumption increases by 1.92 mm for every 1 mm increase in crop water demand.The increase in precipitation will reduce its impact on irrigation water,and the unit precipitation can cause changes in the irrigation water consumption of 1.29,1.74,and 2.72 units in abundant,flat,and dry years,respectively.The irrigation quota in dry years is 20%more than that in abundant and flat years.