基于Aqua Crop的南宁市甘蔗响应气象干旱情景模拟

Simulation of response of sugarcane growth to meteorological drought scenarios based on Aqua Crop model in Nanning

  • 摘要: 南宁市多低山丘陵、岩溶发育, 甘蔗种植以雨养为主, 气象干旱造成的土壤水分亏缺一直是影响该区域甘蔗生长和产量累积的主要因子, 多年来旱灾造成的甘蔗产量损失巨大。为此, 本文基于1979—2018年0.1°格点逐日气象数据, 计算逐日标准化加权平均降水指数(SWAP)并分析了南宁市气象干旱特征及其在甘蔗生育期的可能发生情景, 并采用水分要素驱动的Aqua Crop作物模型, 开展了该区域甘蔗生长、生物量及产量累积过程对不同强度、历时的气象干旱的响应机制模拟研究。结果表明: 经扩展傅里叶幅度检验法(EFAST)对作物模型参数进行敏感性分析和本地化率定后, 该模型模拟研究区的甘蔗产量拟合精度达0.92、均方根误差百分率为3.84%。历时典型气象干旱年情景模拟表明: 产量和生物量累积对各强度气象干旱均有显著响应, 蒸腾量变化只有在分蘖期和伸长期对气象干旱的响应敏感, 而冠层覆盖度对气象干旱的响应具有显著的滞后递减特征。甘蔗各生育期的气象干旱情景模拟发现: 萌芽期发生轻、中旱历时达15 d及以上时甘蔗的上述4个要素开始出现显著响应, 伸长期发生轻、中和重旱历时为5 d及以上时, 甘蔗各要素即出现显著响应, 而成熟期基本不受气象干旱影响。各强度气象干旱情景下, 甘蔗的产量、生物量、蒸腾量的减少率随干旱历时的变化分别为0~24.0%、0~18.5%及0~15.9% (轻旱历时5~35 d), 25.0%~37.0%、20.0%~29.3%及8.0%~24.4% (中旱历时15~45 d), 33.5%~40.0%、26.2%~31.7%及18.9%~25.7% (重旱历时35~50 d)。上述成果揭示了研究区甘蔗生长过程及累计产量等与各强度、历时气象干旱之间的定量映射关系, 可为南宁市解析气象干旱-土壤水分-甘蔗长势的旱灾链式传递机理、多阶段旱灾预警及旱灾动态风险智慧调控等奠定科学基础。

     

    Abstract: Rain-fed sugarcane is mainly cultivated in Nanning, an area with extensive hills and karst. The soil water deficit caused by meteorological drought is a major factor affecting sugarcane growth and yield in this region. The cane yield has experienced huge losses due to drought over the years. Therefore, the daily standardized weighted average precipitation index (SWAP) was calculated using 0.1° grid daily meteorological data from 1979−2018, and the meteorological drought characteristics and possible drought event scenarios during the sugarcane growth period were identified. Finally, the Aqua Crop model was employed to simulate and reveal the mechanisms of sugarcane growth, biomass, and yield accumulation in response to meteorological droughts of multiple intensities and durations. The results showed that the duration, intensity, and frequency of meteorological drought presented significant spatial heterogeneity in Nanning, and meteorological drought events mainly occurred during the sugarcane growth stages of sprouting, stem elongation, and maturity. In addition, seasonal droughts with durations longer than 30 days and sudden droughts with durations less than 30 days occured alternately in the study area. The Aqua Crop model showed good simulation accuracy with the yield determination coefficient (R2) reaching 0.92, and the root mean square error as 3.84%, which were achieved after the sensitivity analysis by the Extended Fourier Amplitude Test (EFAST) and the crop parameter localization for the model. That is, the Aqua Crop model had good simulation accuracy and practical value in this study. The simulation results of a typical meteorological drought year demonstrated that the cane yield (Y) and biomass accumulation (B) were sensitive to meteorological drought of all intensities. However, transpiration (Tr) was sensitive to meteorological drought only during the tilling and stem elongation stages, and canopy coverage (CC) appears to have a significant lag effect in response to meteorological drought. The variation in the above four factors showed an obvious response when the meteorological drought lasted for 15 days or more during the sprouting stage. Nevertheless, the variation in the above four factors appeared to be a significant response when the meteorological drought lasted for only 5 days or more during the stem elongation stage. There was no significant response of the above four factors to meteorological drought for all intensities and durations in the maturity stage. In terms of different meteorological drought intensity scenarios, the reduction rate variations of cane yield (Yw), biomass (Bw) and transpiration (Trw) were, respectively, 0−24.0%, 0−18.5%, and 0−15.9% when the duration of light drought increased from 5 to 35 days; 25.0%−37.0%, 20.0%−29.3%, and 8.0%−24.4% when the duration of moderate drought increased from 15 to 45 days; and 33.5%−40.0%, 26.2%−31.7%, and 18.9%−25.7% when the duration of severe drought increased from 35 to 50 days. These results reveal the quantitative mapping relationship between sugarcane growth process, cane yield accumulation, and meteorological drought for all intensities and durations in the study area, which plays an important scientific supporting role in the chain transmission mechanism analysis of sugarcane drought among meteorological drought, soil moisture, and sugarcane growth, in multi-stage drought early warning systems, and in the intelligent management of drought dynamic risk.

     

/

返回文章
返回