河套灌区作物水氮利用效率多尺度遥感监测及调控研究

The Hetao Irrigation District of Inner Mongolia is located in the arid northwest area. Agricultural production completely depends on the irrigation of The Yellow River and surface irrigation is the main irrigation method in The Hetao Irrigation District. Water and fertilizer use efficiencies of farmlands are low. With the policy decreasing of The Yellow River diversion and water pollution caused by excessive fertilization, it becomes imperative to implementing saving water and reducing fertilization and promoting the agricultural water and fertilization use efficiencies. The research selects the Jiefangzha irrigation area as the study area and selects corns and sunflowers as the study crops. Multi source and multi temporal remote sensing images used as data sources combining with the ground measured data, The study will be monitoring water and nitrogen use efficiencies of crops on five scales of the farmland, the channel, the branch, the canal and the irrigation area by remote sensing. At the same time, The project will reveal the improvement mechanism of water and nitrogen use efficiency under the condition of saving water and reducing nitrogen, and will explore the optimal management mode of water saving and nitrogen reducing through the field experiment. The study will focus on the improvement mechanism of water and nitrogen use efficiencies. At the same time, the research will focus on crops identification，crops yield estimation, estimation of crops evapotranspiration and estimation of crops nitrogen accumulation by remote sensing. The research will analysis the scale effect of water and nitrogen use efficiency and build the scale lifting model. The project will estimate the increase rate of water and nitrogen use efficiency, water-saving amount and amount of nitrogen reducing in the Jiefangzha irrigation area according to the optimal mode of water and nitrogen management, which will provide theoretical guidance and technical support for efficient use of water and fertilizer resources in the Hetao irrigation district.

内蒙古河套灌区地处西北干旱区，农业生产主要依赖引黄灌溉，灌溉方式以地面灌溉为主，水肥利用效率低下，随着政策性引黄水量的减少和过量施肥导致的农田退水污染，灌区实施节水减肥，提升农业水肥利用效率迫在眉睫。本项目针对河套灌区解放闸灌域，以玉米和葵花为研究作物，应用多源多时相遥感影像并结合地面实测数据，对逐级嵌套的农田、斗渠、分干渠、干渠和灌域5个尺度的作物水氮利用效率进行遥感定量监测研究；同时通过田间试验揭示节水减氮条件下作物水氮利用效率提升机制，探索灌区最优节水减氮管理模式。项目重点对作物水氮利用效率提升机制，作物的遥感识别及估产、蒸散量遥感估算和氮素累积量遥感估测开展研究。最后分析作物水氮利用效率的尺度效应，构建尺度提升模型，估算解放闸灌域全面实施田间试验提出的最优节水减氮管理模式后作物水氮利用效率的提升率及节水量和减氮量，为河套灌区层面水肥资源高效利用提供理论指导和技术支撑。

黄河流域生态保护和高质量发展是重大国家战略，河套灌区是内蒙古黄河流域重要粮食生产区，目前河套灌区农业灌溉管理方法传统，效率较低，推进农业遥感在内蒙古黄河流域的应用迫在眉睫。针对上述现状，以内蒙古河套灌区为研究区域，重点对河套灌区种植结构遥感监测、农作物长势监测、土壤墒情遥感监测、农田地表蒸散量、农业灌溉水利用效率遥感估测开展研究。通过研究发现①得到河套灌区典型作物小麦、玉米、葵花、瓜类的典型时间序列NDVI曲线，明确了基于物候信息的作物时间序列NDVI曲线特征差异。构建了基于典型时间序列NDVI曲线特征差异的作物分类决策树模型，实现河套灌区作物高精度分类，作物分类总体精度达82.69%。②在作物生长初期或低植被覆盖下，NDVI和EVI都过高估计植被覆盖度，NDVI估计值略高于EVI的估计值。在作物与生育中期或中等植被覆盖下，NDVI和EVI对作物描述能力相似。在作物生育高峰期或高植被覆盖下，监测作物长势变化EVI比NDVI更敏感。③基于温度植被指数TVDI法实现河套灌区作物生育期土壤墒情遥感监测，并得到生育期内土壤墒情动态变化规律。④采用能量平衡SEBAL模型对河套灌区作物蒸散量进行遥感估算，得到河套灌区作物生育期蒸散量空间分布，玉米生育期平均蒸散量630.22mm，葵花生育期平均蒸散量451.03mm。河套灌区灌溉水利用效率遥感估算结果为0.422。通过上述研究明确了灌区尺度作物遥感分类方法、作物覆盖度及长势遥感监测方法、土壤墒情遥感监测方法、作物蒸散量遥感估算方法和灌溉水利用效率遥感估算方法。该研究成果为河套灌区农业种植结构调整、大尺度农作物覆盖度及长势遥感监测、区域土壤墒情遥感监测、区域作物需水量遥感估算、区域尺度灌溉水利用效率遥感估算提供了重要数据支撑和方法指导。.关键词：遥感；种植结构；作物长势；土壤墒情；作物蒸散量