基于AquaCrop模型的甘蔗干旱机制模拟及旱灾风险评估方法研究

Guangxi province has the largest area of Sugarcane planting in China, and the 90% of its area have no irrigated conditions, which lead to frequent drought of Sugarcane for years and with great economic loss. Aiming at the two characteristics of sugarcane with sensitive to moisture in different growth periods and with significant temperature changes of canopy in vegetative period, this project adopt a water driven Crop Model named AquaCrop to conduct the sugarcane droughts mechanism simulation and its drought risk assessment methods research based on multi-source datasets of remote sensing images, ground observation, in situ measurement and file data cllection. Firstly, The comprehensive drought frequency characteristics of Sugarcane drought can be revealed by calculation and comparison the results of meteorology-remote sensing drought indices and agricultural drought indices. Secondly, the Sugarcane drought mechanism can be emerged by AquaCrop Model after its parameter calibaration and results proof, and furtherly, the Sugarcane biomass and yield also are estimated. Finally, the drought risk quantitative evaluation methods of Sugarcane in Guangxi should be proposed on account of quantitative relationship among the drought frequency, the drought risk of loss and the drought resistance ability of Sugarcane. The research achievement of this project should provide scientific guidance for sugarcane drought of Guangxi in active defense, avoid or reduce the drought loss, crop farming and field management. In addition, the research methods can convenient to promote and apply in other southern crops for drought mechanism and drought loss risk research.

广西甘蔗种植居全国第一，但90%以雨养种植为主，多年来旱灾频发，损失巨大。本课题针对甘蔗全生育期对水分敏感和生长期冠层温度变化显著的特点，以水分因子主控驱动的AquaCrop作物模型为主要工具，集遥感、地面观测、现场测定、文献资料等多源数据，开展甘蔗干旱机制模拟及旱灾风险评估方法研究。首先，通过多个气象-遥感综合干旱指标及典型农业干旱指标计算对比论证获得广西甘蔗历史干旱频率综合特征；其次，在对AquaCrop模型进行参数率定和验证的基础上，揭示广西甘蔗响应水分亏缺的干旱机制，并估算生物量及产量；最后，在建立广西甘蔗干旱频率~旱灾损失潜在风险~抗旱能力定量关系的基础上，提出基于AquaCrop模型的广西甘蔗旱灾风险定量评估方法。课题研究成果可为广西甘蔗干旱的主动预防、旱灾规避或降低、作物耕种与田间管理等方面提供科学指导。研究方法亦可快速的推广应用于南方其他作物干旱机制与旱灾风险研究中。

项目基于广西石山丘陵众多、岩溶发育且土壤保水能力差的本底条件，针对主控甘蔗生长的水分因子，汇集气象、水文及土壤多源要素资料，借助AquaCrop作物模型开展了广西甘蔗干旱机制模拟及旱灾风险评估研究。结果表明：（1）广西具有季节性和骤发性气象干旱叠加作用并促使农业（甘蔗）干旱及旱灾形成的特征；且月~季尺度和日~候尺度分别较好地表达这两种干旱模式的演变及其频率特征。（2）土壤水分盈亏显著影响广西甘蔗生长，尤其在中、末生育期，全生育期降雨量低于800mm会导致广西甘蔗总体减产超过30%，并且地域差异显著。（3）广西甘蔗旱灾损失及其旱灾风险对5-8月的降水更为敏感，且桂中及桂西北地区旱灾风险显著高于其他地区。项目研究成果可为广西农业（甘蔗）干旱全过程精细化识别及预警、田间灌溉调控、旱灾损失风险评估和应急提供坚实的科学支撑。