1960—2020年新疆主要作物需水量时空特征分析

Spatio-temporal characteristics of water requirement of main crops in Xinjiang from 1960 to 2020

作物需水量和作物灌溉需水量的时空分析对水资源优化配置和灌溉制度制定至关重要。为了解新疆主要作物棉花、春小麦、冬小麦和玉米生育期需水量和灌溉需水量的时空特征及影响因素,本文基于1960—2020年逐日气象观测数据,采用Penman-Monteith公式和单作物系数法,利用去趋势预置白(TFPW)的Mann-Kendall(TFPW-MK)研究4种作物需水量变化特征,并通过重标极差(R/S)分析法预测未来作物需水量和灌溉需水量的时空演变趋势;运用随机森林模型的重要协变量特征识别原理,分析气象因素与作物需水量的重要性排名,探究了作物需水量的变化成因。结果表明:1)61年来,新疆主要作物需水量总体呈现“先增后减又增”的变化趋势;作物需水量和灌溉需水量从大到小均依次为:棉花>玉米>冬小麦>春小麦;空间上呈现“南疆>北疆、东南>西北、东部>西部”的格局;主要作物需水量变化范围为:棉花为381.20~991.20 mm(均值为654.94 mm),玉米为350.26~924.48 mm(均值为607.98 mm),春小麦为361.96~709.69 mm(均值为464.89 mm),冬小麦为266.47~753.62 mm(均值为495.70 mm);灌溉需水量变化范围为:棉花为49.49~975.88 mm(均值为563.19 mm),玉米为52.47~910.85 mm(均值为530.18 mm),春小麦为42.58~701.29mm(均值为409.28 mm),冬小麦为21.94~741.77 mm(均值为418.26 mm),自80年代中后期开始,灌溉需水量下降幅度大于需水量。2)TFPW-MK分析中,近61年来,分布在塔里木盆地北部边缘的沙雅和阿克苏、东疆的巴里坤等12个站点需水量呈上升趋势;分布在塔里木盆地中部的塔中、北疆的克拉玛依和南疆的阿图什等区域的27个站点需水量逐步降低;其余站点呈上下波动。3)使用R/S方法对未来需水量的预测中,北疆的塔城、托里、富蕴和乌鲁木齐站,东疆的巴里坤,南疆的沙雅、乌恰、塔中、且末和柯坪等站点4种作物需水量和灌溉需水量在未来会减少,而东疆的红柳河、巴里坤与巴音布鲁克的春、冬小麦需水量在未来呈现上升趋势。4)在作物全育期中,风速和气温是新疆主要作物需水量的最重要影响因素,而降水对新疆主要作物需水量的重要性最小。该研究较为全面的为新疆农业高效用水和灌溉措施的制定提供决策和依据。

Spatio-temporal analysis of crop water requirement and crop irrigation water requirement is crucial to the optimal allocation of water resources and the formulation of irrigation systems.The objective of this study is to understand the spatio-temporal characteristics and influencing factors of the water requirement during the growth period and irrigation water requirement of the main crops in Xinjiang,cotton,spring wheat,winter wheat,and corn.Based on the daily meteorological observation data from 1960 to 2020,the Penman-Monteith formula and the single crop coefficient method were adopted in this study,and Mann-Kendall(TFPW-MK)of Detrended Preset White(TFPW)was used to study the changing characteristics of water requirement of four crops.The temporal and spatial evolution trend of crop water requirement and irrigation water requirement were predicted by rescaled range(R/S)analysis.Using the principle of important covariate feature identification of the random forest model,the importance ranking of meteorological factors and crop water requirement was analyzed,and the causes of changes in crop water requirement were explored.The results show that:1)the water requirement of major crops in Xinjiang had generally shown a trend of“increase first,then decrease and then increase”for 61 year.The order of crop water demand and irrigation water requirement from large to small was:cotton>corn>winter wheat>spring wheat.In terms of space,there was a spatial distribution of“Southern Xinjiang>Northern Xinjiang,Southeast>Northwest,East>Western”.The variation range of water requirement for major crops was:cotton 381.20–991.20 mm(mean 654.94 mm),corn 350.26–924.48 mm(mean 607.98 mm),spring wheat 361.96–709.69 mm(average 464.89 mm),winter wheat 266.47–753.62 mm(average 495.70 mm).The range of irrigation water requirement was:cotton 49.49–975.88 mm(average 563.19 mm),corn 52.47–910.85 mm(average 530.18 mm),spring wheat 42.58–701.29 mm(average 409.28 mm),winter wheat 21.94–741.77 mm(average 418.26 mm).Since the middle and late 1980s,irrigation water requirement decreased more than water requirement.2)According to the TFPW-MK analysis,in the past 61 years,the water requirement of 12 stations mainly distributed in the northern edge of the Tarim Basin,including Shaya and Aksu,and Baekol in the eastern Xinjiang,showed an upward trend.The water requirement of 27 stations in Karamay in Xinjiang and Artux in southern Xinjiang gradually decreased;the rest of the stations fluctuated up and down.3)In the prediction of future water demand using the R/S method,four crop water demand and irrigation water demand at Tacheng,Toli,Fuyun and Urumqi stations in northern Xinjiang,Baekol in eastern Xinjiang,and Shaya,Wuqia,Tazhong,Qiemo and Kalpin stations in southern Xinjiang will decrease in the future,while spring and winter wheat water demand at Hongliuhe,Baekol and Bayanbulak in eastern Xinjiang will show an increasing trend in the future.4)During the crop growth period,wind speed and temperature were the most important factors affecting the water requirement of major crops in Xinjiang,while precipitation was the least important factor for the water requirement of major crops in Xinjiang.This research comprehensively provides decision-making and basis for the formulation of high-efficiency agricultural water use and irrigation measures in Xinjiang.