江西省农田灌溉用水变化驱动因子识别及贡献率分解

Factors influencing the change in irrigation water usage in Jiangxi province

【目的】江西省农田灌溉用水变化极大地影响了用水总量,识别农田灌溉用水量的驱动因子,揭示其影响机制和变化特征能够为科学管理农业取用水提供重要参考。【方法】分析江西省及各地市用水结构信息熵及均衡度演变特征,采用LMDI分解法识别影响农田灌溉用水量的驱动因子,并定量评估其贡献率,重点研究其与气象因素的关系,为优化用水结构、发挥水资源刚性约束作用提供支撑。【结果】基于LMDI分解法识别的江西省及各地市农田灌溉用水变化驱动因子为亩均净灌溉用水量、农田灌溉水有效利用系数、有效灌溉面积和实际灌溉比例,其中农田灌溉水有效利用系数始终以抑制因子表现,其余3个因子表现出双向性;相关分析表明,亩均净灌溉用水量及其贡献主要受降水影响;仅考虑非气象驱动因素,江西省大部分时段农田灌溉用水变化量表现为负值,说明灌溉工程状况和管理水平不断增强,农田灌溉用水量降低的主要原因是农田灌溉水有效利用系数的提高;省内上饶、抚州、宜春、吉安、赣州5个重点地市具有较高的农业节水需求和潜力。【结论】考虑到实际灌溉比例和有效灌溉面积将保持持续增长态势,建议江西省抓住重点地市采取措施,如大力推进大中型灌区节水改造、增强灌区科学调配水资源的能力等,促进全省农田灌溉水有效利用系数加快增长,以达到提升灌溉用水效率、挖掘农业节水潜力、缓解用水压力目的。

【Objective】Irrigation is the largest water consumer in many regions.Understanding its variation and the underlying determinants is important for improving water management.Taking Jiangxi province as an example,we analyze the variation in its irrigation water usage,as well as the factors that influence the changes.【Method】Based on the information entropy and the balance in water utilization across the province,the logarithmic mean divisia index(LMDI)decomposition method was used to identify the meteorological factors that affect and contribute to irrigation water usage.【Result】The change in agricultural irrigation water consumption in the province is affected mainly by net irrigation water consumption per acre land,effective utilization coefficient of irrigation water,and effective irrigation areas,and actual irrigation ratio.The impact of irrigation water use efficiency negatively affected the change in irrigation water usage,while the impact of other factors varied with other conditions.Correlation analysis showed that the net irrigation water consumption per acre land and its contribution to irrigation water usage are affected mainly by rainfall.Excluding weather-related factors,the change in irrigation water consumption in the province was negative,indicating that the management of irrigation engineering projects has been improved.The increased irrigation water utilization efficiency is the main reason behind the decreased agricultural irrigation water consumption.Five cities in the province,including Shangrao,Fuzhou,Yichun,Jian,and Ganzhou,still have room for implementing water-saving irrigation.【Conclusion】Given the potential growth in the ratio of the effective irrigation areas to actual irrigation areas,the province should take measures by,for example,developing water-saving projects in large and medium-sized irrigation areas and optimizing water resource allocation,to improve effective irrigation water utilization coefficient and alleviate water pressure.