| As a large agricultural country with an extreme shortage of water resources,agriculture accounts for more than 60% of water consumption,and more than 90% of agricultural water consumption is used for agricultural irrigation.Therefore,it is important to measure and analyse the trend of irrigation water consumption and its driving factors,and to quantitatively analyse the impact effectiveness of each driving factor,identify the key impact factors and,according to the impact of each driving factor on irrigation water consumption To the extent that each driver has an impact on irrigation water consumption,feasible suggestions for saving irrigation water are put forward,which are important for improving irrigation water conservation and ensuring sustainable development of water resources.This paper takes 15 farms in the Jiansanjiang Reclamation Area as the research object,and uses meteorological data,crop fertility data,crop cultivation data and irrigation water use data of each farm from 1995 to 2018 to calculate the evapotranspiration of reference crops in the Reclamation Area based on the Penman-Monteith formula,and combines the single-crop coefficient method to calculate the evapotranspiration of crops(rice,maize,soybean,wheat,hemp,green fodder and sugar beet)in the Jiansanjiang Reclamation Area during fertility.The effective rainfall and irrigation water requirements of different crops were estimated by using the formulae related to effective rainfall and net irrigation quota,and then the irrigation water requirements of each farm were further measured.The effect of changes in cropping area,cropping structure,climate change and improvements in water conservation measures on irrigation water use at each farm in the Jianshanjiang Reclamation Area was quantified using a log-averaged Dirham exponential decomposition model(LMDI)to identify the key drivers of irrigation water use.The main findings of the study are as follows.(1)Annual evapotranspiration of reference crops in the Jianshanjiang reclamation area ranged from 549.86 mm to 670.60 mm from 1995 to 2018,and the multi-year average annual evapotranspiration of reference crops was 606.68 mm.there were significant differences in crop water demand,effective rainfall and crop irrigation water demand for different crops during the reproductive period,and crop water demand,effective rainfall and crop irrigation water demand for the same crop during the reproductive period The inter-annual variation in crop water demand,effective rainfall and crop irrigation water demand for the same crop showed fluctuating trends and was relatively flat.The multi-year average water requirements of rice,maize,soybean,wheat,hemp,green fodder and sugar beet during the reproductive period were 484.88 mm,427.14 mm,319.11 mm,288.45 mm,296.14 mm,305.62 mm and 362.9mm respectively,while the effective rainfall was298.4mm,295.76 mm,263.52 mm,203.44 mm and 181.44 mm respectively.,203.44 mm,181.01 mm,184.01 mm,225.34 mm,the irrigation water demand was 186.49 mm,131.38 mm,55.58 mm,85mm,115.13 mm,121.6mm,168.67 mm respectively.(2)The planted area and the total planted area of the Jianshanjiang reclamation area showed a significant increase from 1995 to 2018,and the planted area of all farms showed a significant increase in 2007;there was a large-scale change in the planting structure,from wheat and soybeans as the main crops in 1995 to rice as the main crop in 2018;the net crop irrigation quotas,which were larger in 1995,2007,2008 2017 and 2018,reflecting favourable climatic conditions for crop growth in those years,while smaller amounts in 1997,2006,2012 2013 and 2016 indicate unfavourable climatic conditions for crop growth in those years;the irrigation water use coefficient increased from 0.362 in 1995 to From 1995 to 2018,the amount of irrigation water used by farms in the Jiansanjiang Reclamation Area and as a whole showed an increasing trend,with a gradual increase in the amount of irrigation water used each year over time from 1995 to 2010,and a significant increase in the amount of irrigation water used by each farm in 2007,and from 2011 to From 2011 to 2018,annual irrigation water use tended to stabilise.(3)The results of the LMDI additive decomposition of irrigation water use show that Daxing Farm,Qianfeng Farm and Honghe Farm exhibit the greatest influence of the acreage effect on irrigation water use,indicating that the acreage effect is the key driver of irrigation water use growth in Daxing Farm,Qianfeng Farm and Honghe Farm;859 Farm,Shengli Farm,Qixing Farm,Qindeli Farm,Qinglongshan Farm,Qianjin Farm,Jiye Farm This indicates that the scale effect is a key driver of irrigation water use growth in all these farms.The climate change effect has a certain contribution to irrigation water use growth,but the effect is relatively small,and the effect of water conservation measures has a dampening effect on irrigation water use growth in all farms.(4)The LMDI of irrigation water use is a key driver of irrigation water use growth.(4)The LMDI multiplicative decomposition of irrigation water use shows that the effect of cropping area and cropping structure on each farm in the Jianshanjiang reclamation area was greater than 1 in the four time periods 1995-2000,2001-2006,2007-2012 and 2013-2018,and that the climate change effect was inconsistent across farms and had a relatively small effect on irrigation water use.The effect of climate change was inconsistent across farms and had a relatively small impact on irrigation water use,and the effect of water saving measures was less than 1 across all periods,suggesting that changes in acreage and cropping structure were the main factors contributing to increased irrigation water use,with climate change having a smaller impact on irrigation water use.The effect of water-saving measures in recent years was more apparent in the periods 2007-2012 and 2013-2018,reflecting the effectiveness of the "Water Conservation and Food Increase Initiative" advocated by the State.(5)Through the analysis of irrigation water consumption and the driving factors of irrigation water consumption in each farm in the Jianshanjiang reclamation area,it is recommended that in order to ensure the healthy and sustainable development of agriculture in the reclamation area,irrigation should be applied to crops during the rapid fertility period and the fruiting period according to the water shortage of different crops,which can effectively alleviate the water shortage of crops at the current fertility stage and improve crop yields.The increase in rice cultivation area and cropping structure are the main factors influencing the increase in irrigation water consumption on the farms in the Jianshanjiang region.Maize acreage and cropping structure contributed to the increase in irrigation water use on each farm.Increasing the planting structure of soybeans,wheat,hemp,green fodder and sugar beets has a greater effect on reducing irrigation water consumption than increasing the planting area does on promoting irrigation water consumption.In the future,the reclamation area should continue to vigorously develop water conservation measures and improve water management in order to achieve healthy and sustainable agricultural development in the reclamation area. |
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