衡邵干旱走廊耕地种植结构水分供需评估及其优化

Evaluation of water supply and demand and optimization under the planting structure of cultivated land in the Hengshao Arid Corridor

[目的]从种植结构视角,探究耕地利用下水分供需态势并实现其多目标优化调整,为“以水定地”及耕地资源可持续利用提供理论参考。[方法]以衡邵干旱走廊为研究区,在气象站点、土地利用、作物种植以及农业社会经济等多源数据支持下,基于耕地种植结构视角,微观精准揭示1980-2020年不同气候类型年份耕地种植结构下的水分供需态势及灌溉需求,并构建不同灌溉需水情景下的耕地种植结构多目标优化模型,同时设定“水-土-粮”多重约束,确定耕地种植结构优化策略。[结果](1)双季稻和油菜全生育期的水分自然供给优于单季稻及玉米,且水稻耗水量较高,尤其干旱年双季稻平均需水量高达608.29 mm;(2)水稻和玉米全生育期的有效降水空间与需水格局相异,导致研究区东南部的作物干旱情势加剧,而油菜整体水分供需态势良好;(3)双季稻和单季稻的水分亏缺程度较高,年均净灌溉需水量分别达到303.68 mm、257.00 mm,旱生作物的水分供需矛盾较小,种植管理过程无需过度依赖农业灌溉;(4)经种植结构优化,在设定节水目标并实现优化调控后能够显著提高耕地生产综合效益,尤其是权重情景3的湿润年水资源约束下预期粮食产量可提升5.12%;权重情景1和2的湿润年水资源约束下作物种植减税纯收益可提升22.34%。[结论]衡邵干旱走廊在干旱年的种植结构应基本保持稳定,平水年可适当增加单季稻面积、调减旱作物种植比例,湿润年可大幅增加粮食作物播种面积并调减油菜面积,以提升耕地种植的综合效益。

[Objective]This study aimeds to explore the water supply and demand dynamics of cropland from a planting structure perspective,achieve multi-objective optimization adjustments,and provide theoretical references for the principles of“allocating land based on water resources”and sustainable utilization of cropland resources.[Methods]Taking the Hengshao Arid Corridor as the research area and supported by various data sources including baseline meteorological data,land use,crop planting,and agricultural socioeconomic data,this study employed a crop water balance evaluation model to intricately reveal the water balance trends and irrigation requirements under diverse planting structures across various climate years from 1980 to 2020.A multi-objective optimization model for cropland planting structure was constructed under different irrigation water demand scenarios,incorporating multiple constraints related to water-land-crop.This led to the identification of optimized strategies for cropland planting structure.[Results](1)Double-season rice and rapeseed have a more reliable water supply throughout their growth periods compared to single-season rice and maize.Rice demands higher water supply,especially during drought years,where the average water demand for double-season rice reaches as high as 608.29 mm.(2)The spatial distribution of effective precipitation and water demand patterns differs for rice and maize,exacerbating the drought situation in the southeastern part of the study area,whereas the water balance for rapeseed remains favorable.(3)The water deficit is more pronounced for doubleseason and single-season rice,with average net irrigation water requirements of 303.68 mm and 257.00 mm,respectively.Water supply-demand conflicts for drought-tolerant crops are less prominent,reducing the reliance on agricultural irrigation during the planting management process.(4)After optimization of the planting structure,the comprehensive benefits of cropland production can be significantly improved after setting water-saving targets and achieving optimal regulation,especially that the expected grain yield can be increased by 5.12%under the wet-year water constraints of the weighted scenario 3;and the net tax-reduced income from crop cultivation can be increased by 22.34%under the wet-year water constraints of the weighted scenarios 1 and 2.[Conclusion]The planting structure of the Hengshao Arid Corridor should basically remain unchanged in dry years.In normal years,the area of single-season rice can be appropriately increased and the proportion of dry crop planting can be reduced.In humid years,the planting area of grain crops can be significantly increased and the area of rapeseed can be reduced to improve the comprehensive benefits of cropland planting.