基于SPEI的广西甘蔗生育期干旱时空演变特征分析

    Spatial and temporal evolution characteristics of drought in Guangxi during sugarcane growth period based on SPEI

    • 摘要: 干旱是影响甘蔗生产最严重的农业气象灾害之一,在气候变化背景下,甘蔗生育期干旱时空演变特征对于蔗糖生产的防灾减灾具有重要意义。该文以中国甘蔗主产区广西为研究区,利用1971-2017年气温和降水量数据,采用标准化降水蒸散指数SPEI(standardized precipitation evapotranspiration index)作为干旱指标,在充分验证其对干旱监测适用性的基础上,以甘蔗不同生育期为时间尺度,同时考虑研究区甘蔗播种期差异,分析广西甘蔗不同种植区各等级干旱时空演变特征及规律,结果发现:1)利用SPEI可以较客观的反映甘蔗生育期干旱。SPEI与甘蔗种植区典型干旱事件的时间、强度吻合度较高,甘蔗各生育期及全生育期SPEI与不同深度的土壤湿度多呈显著相关,多数通过了0.01水平的显著性水平检验。2)1971-2017年,甘蔗各个生育期多呈干旱化趋势。其中,分蘖期干旱化趋势最强,苗期次之,茎伸长期干旱化趋势最弱,工艺成熟期呈湿润化的变化趋势。3)甘蔗不同生育期干旱周期变化明显。在10~15 a时间尺度上,多有4~6个干-湿循环,5 a时间尺度下则有更多的干-湿循环交替,相较于分蘖期和工艺成熟期,茎伸长期、苗期周期变化更明显。4)甘蔗各个生育期干旱空间分布特征差异较大。甘蔗工艺成熟期干旱发生频率最高,分蘖期干旱最低,茎伸长期和苗期相当。甘蔗各个生育期均以轻旱为主,重旱和特旱发生频率较低,其中茎伸长期和工艺成熟期中旱频率明显高于其他生育期。对于甘蔗苗期和茎伸长期,桂北地区干旱发生频率高于其他地区,而对于分蘖期和工艺成熟期,桂中地区干旱发生频率较高。

       

      Abstract: China is the third largest sugar producer in the world, and sugar industry is the most important economic pillar industries in south China. Drought is one of the most serious agro-meteorological disasters affecting sugarcane production. Under the background of climate change, to analyze the temporal and spatial evolution characteristics of drought in sugarcane planting area is of great significance for disaster prevention and improving the ability of sugarcane production to cope with climate change. In this paper, Guangxi Zhuang Autonomous Region which is located in 104°26′-112°04′E,20°54′-26°24′N was taken as the research area. Temperature and precipitation data from 1971 to 2017 and the standardized precipitation evapotranspiration index (SPEI) were used to analyze the drought characteristics. Firstly, historical typical drought events and measured soil relative humidity were used to verify the applicability of SPEI to sugarcane drought monitoring. Then, taking the sugarcane growth stages including seedling stage, tillering stage, stem elongation stage, maturity stage and whole growth stage as time scale, and considering the difference of sugarcane sowing time, the spatial and temporal evolution characteristics and variation rules of light drought, medium drought, severe drought and extreme drought in different sugarcane planting areas in Guangxi were analyzed by climate trend rate, wavelet analysis and GIS spatial technology. The results showed that the occurrence time and intensity of typical drought events during 2003 to 2011 in sugarcane planting area were good fit with SPEI, and the correlation between soil moisture of 0cm to 50cm depths and SPEI were good in each sugarcane growth period and the whole growth period and most of them passed the significance level test, all this indicates that SPEI could reflect drought objectively. The climate trend rate analysis showed that, from 1971 to 2017, the drought trend of sugarcane was the strongest at the tilling stage, the second at the seedling stage, the weakest at the stem elongation stage, while the mature stage showed a wet trend. The wavelet analysis results showed that, for the time scale of 10 to15 a, there were about 4 to 6 dry-wet cycles in each sugarcane growth stages, and for the time scale of 0 to 5 a, dry-wet cycles alternation were more obvious. There were great differences in each growth period, and the change of stem elongation and seedling stage were more obvious than those of tilling stage and technological maturity stage. From the seedling stage to the maturity stage, the spatial distribution characteristics and variation rules of drought in the sugarcane growing areas in Guangxi were of great difference. Generally speaking, drought frequency is highest in maturity stage and lowest in tillering stage and similar in stem elongation and seedling stage. Frequency of light drought was high for all sugarcane growth stage and relative low for medium drought, severe drought and extreme drought, furthermore, frequency of middle drought was obviously higher in stem elongation stage and maturity stage than other growth stages. For sugarcane seedling stage and stem elongation stage, drought frequency was higher in northern Guangxi than other areas, while for tillering stage and maturity stage, drought frequency was higher in central Guangxi.

       

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