| Drought disaster is one of the major natural disasters in Guangxi.According to historical records.From 1700 to 1945, Guangxi drought 152 times,during these years,there are 12 years suffered wide range of drought.From 1950 to 1990, almost every year has drought.Drought is not only impacts on the development of industry and agricultureseriously, but also restricted the economic development of Guangxi.In order to understand the regular of drought and find the countermeasures of governance drought better,this paper will analyzes the space-time regular of drought in Guangxi,and partition Guangxi according to the characteristics of the droughton the basis of RS and GIS spatial analysis.In this paper, the research content includes: The article has summarized the various of drought monitoring methods at home and abroad, and They can be divided into two categories:the methods based on the historical meteorological data and the one based on the remote sensing information.At the same time, this paper has discussed the advantages and disadvantages of each method and their applicable scope.This paper has analyzed the spatial and temporal variations of drought in Guangxi by using SPEI,divided Guangxi witn spring drought area and autumndrought area,and analysed the trends of them.The paper discussed the defect of TVDI, and make use of the improved TVDI for drought monitoring of typical drought years.There are differences between the monitoring results by using SPEI and TVDI,so we can know there are other impact factors,which determine whether this area is dry or not.According to the distribution of these factors,we can partition Guangxi.We can finely come to the conclusion:(1) The Meteorological data come from the weather stations,so we must use spatial interpolation to response if this space is dry or not,and this leads to errors.So the Remote sensing methods are more reasonable.(2) Each drought monitoring model has their own conditions.Among them TVDI has the wider applicable scope,but it still exists disadvantages, For example,its formula can be saturated easily,the space fitting is not accurate,and it may be limited by time.(3) The different scales of SPEI has a different meaning.From the 3 months scaleSPEI,we can know:In spring,the northwest of Guangxi and the beibu gulf has a high frequency of drought.In autumn the northeast of Guangxi may come into drought easily.(4)The spring-drought area has seven levels of cyclical fluctustions: 2.21 months,9.42 months, 3.62, 3.92, 11.77, 15.69 and 47.08 years. The development of the drought in spring-drought area is very gentle. The autumn-drought area also has seven levels of cyclical fluctustions: 3.34 months and 9.11 months, 2.14, 4.28, 11.77, 23.54 and 47.08 years. The drought in autumn-drought area is more and more serious.(5)The drought in Guangxi is not serious,and the probability of occurrence of severe drought is very small.(6) In several types of landforms in Guangxi, mountain can effectively alleviate the drought.Where there is Karst the drought is more serious. Where there are Calcareous soil, purple soil, regosols the drought is more serious too.(7) In very humid area,we can alleviate the drought through the planting of woodland. In the wet and normal area the situation can also be maintained through the planting of grassland and woodland. in light-drought region,we can alleviate the drought by expanding the area of paddy field.But in the heavy-drought region it is not very effective that alleviate the droughtthrough the adjustment of land use structure.(8) According to different seasons, different drought types, landform types and different soil types, divides Guangxi into 20 little district.(9)we should consider the different crops in the study area when we talk about the agricultural drought regionalization,There are severalinnovations in this paper. The first is to divides Guangxi into spring-drought area andautumn-drought area.The second is to analysis the SPEI sequences of two drought area and put forward the drought trend by using EEMD and FFT.The third is to improve the traditional TVDI methods. The last one is the contrastive analysis by using remote sensing and not-remote sensing method. |
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