广西糖料蔗种植区干旱遥感时空分析

Spatiotemporal analysis of drought in sugarcane planting areas of Guangxi by remote sensing

广西是我国最重要的糖料蔗产区,开展蔗区干旱遥感监测具有重要的现实意义。本研究利用MODIS遥感数据产品MOD16/MYD16计算2002—2018年间广西糖料蔗种植区干旱严重程度指数(drought severity index,DSI)空间分布,分析揭示广西糖料蔗种植区不同干旱等级时空演变特征,然后利用一元线性回归、Mann-Kendall趋势检验和Hurst指数等3种方法分析广西糖料蔗种植区干旱变化趋势。结果表明,2002—2018年间广西糖料蔗种植区干旱主要集中在桂中蔗区、桂东南蔗区、桂西南蔗区及桂西北蔗区;DSI年均值为-0.59,最大值出现在2010年和2002年,最小值出现在2016年;2002—2018年间广西糖料蔗种植区DSI总体上显现微弱下降趋势,年降速为0.07%;从干旱空间重心来看,不同生育期的干旱面积重心呈现出由中部向西北方向扩张趋势,重心迁移轨迹为桂中蔗区>桂西南蔗区>桂西北蔗区;从各年度来看,广西糖料蔗种植区DSI年际波动明显,存在显著上升和下降的突变年份,表明干旱在各年度之间显现出易变性。在未来气候变化背景下,广西蔗区干旱变化趋于严峻。因此,加强蔗区抗旱减灾防御,仍然是减轻重大干旱对糖料蔗生产影响的重要措施。

Guangxi is the most important sugarcane producing area in China.Remote sensing of drought in sugarcane planting areas is of great practical significance to decision-making for the anti-drought campaign in Guangxi where sugarcane planting is mainly on the farmland without irrigation guarantee.This study intends to examine the issue of remote sensing monitoring of drought in sugarcane planning areas in Guangxi.MODIS data product MOD16/MYD16 was used to calculate the drought intensity index(DSI)in Guangxi sugarcane planting areas for a period from 2002 to 2018.On the basis of this calculation,the spatiotemporal characteristics of different drought grades in Guangxi sugarcane planting areas were analyzed.In order to reveal the changing trend of the drought severity in the sugarcane planning areas,three methods,i.e.unary linear regression,Mann-Kendall trend test and Hurst index,were used in the study to analyze the change trend of drought in the sugarcane planting areas of Guangxi.The results showed that the drought in Guangxi during the period from 2002 to 2018 mainly happened in the center,the southeast,the southwest,and the northwest sugarcane areas.The annual average of DSI was-0.59 during the period.Very high DSI was observed in two years,i.e.2010 and 2002,implying that sugarcane planting in Guangxi experienced the most severe drought in the two years.Very low DSI was seen in 2016,indicating the minimal impact of drought on the planting areas this year.The change of DSI in the sugarcane planting areas of Guangxi showed a trend of a slight decrease from 2002 to 2018,with an annual rate of-0.07%.In terms of the spatial center of gravity of drought,the center of gravity of drought areas in different growth periods showed a trend of expansion from the center to the northwest,and the path of gravity center shift was as follows:central planting area>southwest planting area>northwest planting area.From the perspective of years,DSI in each year revealed a remarkable fluctuation during the period in question.Sharp changes in DSI might also be seen in some years,implying that drought had variability among years in Guangxi.The spatiotemporal variation of drought in Guangxi is obviously related to the climate change in the areas.Therefore we believe that sugarcane planting in Guangxi might continuously face the challenges from the frequent occurrence of the drought of various grades as a result of future climate change.Remote sensing monitoring of the drought can provide useful information on drought events and their dynamics for anti-drought campaigns to reduce the impact of drought on sugarcane planting in Guangxi.