2001—2019年长江中下游农业干旱遥感监测及植被敏感性分析

Remote Sensing Monitoring of Agricultural Drought and Vegetation Sensitivity Analysis in the Middle and Lower Reaches of the Yangtze River from 2001 to 2019

  • 摘要: 长江中下游地区是中国最重要的粮食产区之一,近年来,由于极端天气影响,长江中下游地区的农业生产时常受到干旱灾害威胁。利用植被条件指数(vegetation condition index, VCI)、温度条件指数(temperature condition index, TCI)及植被健康指数(vegetation health index, VHI)对2001—2019年长江中下游地区农业干旱的时空演变情况进行监测,探究长江中下游地区VCI、TCI在VHI指数中的最优权重比例,挖掘不同植被对干旱的敏感性差异,同时基于气候变化背景分析长江中下游六省一市的干旱趋势。结果表明,VCI和TCI指数能够分别反映地区植被生长异常和热量异常;当VCI和TCI的权重分配比为7∶3时,VHI指数能够结合两种指数的特点,在长江中下游地区农业干旱监测上更有优势;不同植被对干旱的敏感性不同,在长江中下游地区,农作物对干旱的敏感性最高,森林最低,草地介于二者之间;在气候变化背景下,近20年来,长江中下游地区呈现逐渐湿润的趋势,干旱风险逐步降低,其中湖北、湖南、安徽、江西和浙江等地湿润趋势明显,而江苏和上海地区湿润趋势较弱,在极端气候下仍存在一定的干旱风险。相关结果能够为长江中下游地区各省市旱情预警及抗旱措施制定、区域农业生产管理提供参考。

     

    Abstract:
      Objectives  The middle and lower reaches of the Yangtze River, including Hubei, Hunan, Jiangxi, Anhui, Jiangsu, Zhejiang and Shanghai, are important planting bases of commercial grain in China. However, at present, there are relatively few studies on agricultural drought in this region, and there is a lack of attention to the response of land cover types to drought. Moreover, in the context of climate change, the evolution and trend of agricultural drought in the middle and lower reaches of the Yangtze River need further discussion.
      Methods  This study used MODIS (moderate resolution imaging spectroradiometer) V6 products to construct vegetation condition index (VCI), temperature condition index (TCI) and vegetation health index (VHI) to monitor the temporal and spatial evolution of agricultural drought in the middle and lower reaches of the Yangtze River from 2001 to 2019, and further explored the drought sensitivity of different vegetative types.Based on the concept of climate change, this study analyzed the drought trends in six provinces and one city in the middle and lower reaches of the Yangtze River. The results of the above three indices were further evaluated by standardized precipitation index (SPI) on different time scales, obtained and calculated from the CHIRPS V2.0 dataset.
      Results  The results show that the VCI and TCI could monitor the long-term abnormal vegetation growth and heat anomalies, respectively, but neither index could provide comprehensive overview of drought conditions. Combining the advantages of both indices with the weights of 0.7 and 0.3 for VCI and TCI, respectively, the VHI, was more effective in agricultural drought monitoring in the middle and lower reaches of the Yangtze River. Different vegetation showed different drought sensitivity in study. Crops have the highest sensitivity to drought, forests are the lowest, and grasslands are somewhere in between. In the context of climate change, Jiangxi, Hunan, Hubei, Zhejiang, and Anhui show an intense wet trend in the past 20 years, while the Jiangsu and Shanghai show a weak wet trend.
      Conclusions  Drought indices should be integrated to provide comprehensive evaluation of agricultural drought in the middle and lower reaches of the Yangtze River. Jiangsu province and Shanghai city are still at drought risk due to the weak wet trend and the local agricultural department should take drought mitigation measures to prevent economic losses. In the middle and lower reaches of the Yangtze River, croplands have the most obvious response to drought, indicating that crops are most sensitive to drought than grasses and forests, more attention should be paid to agriculture management. The relevant results can provide reference for the early warning of drought in various provinces and cities in the middle and lower reaches of the Yangtze River and help the management of regional agricultural production.

     

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