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    基于GIS的广西西江流域石漠化动态分析

    Dynamic variation analysis of rocky desertification in Xijiang River Basin of Guangxi based on GIS

    • 摘要: 为及时掌握各项综合治理措施开展过程中广西西江流域石漠化动态变化情况, 基于2001、2006、2011和2016年4期MODIS NDVI影像数据, 综合运用RS与GIS技术, 提取西江流域石漠化空间信息, 分析西江流域石漠化动态特征。结果表明:2001—2016年间西江流域石漠化面积由18.06%下降至7.34%, 且石漠化面积降幅逐年增大。石漠化集中分布于西江流域中部及西部地区, 该区石漠化面积占全流域石漠化总面积的87.72%。桂贺江与左江流域石漠化缩减速率呈现出先增加后减少的趋势, 其余各子流域石漠化缩减速率均在2011—2016年间达到最大值。石漠化演化的实质是不同等级石漠化相互转移的过程, 其中低等级石漠化易向相邻等级石漠化转移。流域石漠化演变呈现高等级石漠化逐步向低等级石漠化转变的特征, 表明针对广西西江流域石漠化的治理已取得一定成效, 但石漠化好转的同时, 部分地区仍存在石漠化恶化的问题, 因此需要进一步加强流域石漠化监测力度, 因地制宜调整与优化石漠化综合治理措施。

       

      Abstract:
      Background At present, numerous scholars have carried out a lot of research and demonstration work in view of Xijiang River Basin of Guangxi Zhuang Autonomous Region duo to its extensive rocky desertification, mainly including scale regional desertification monitoring and rocky desertification formation.But the distribution, the dynamic characteristics and the mechanism of rocky desertification in the whole basin are still lack of effective monitoring.In order to understand the dynamic characteristic of rocky desertification of Xijiang River in Guangxi province at once, GIS and RS technology were used to analyze the status of rocky desertification in Xijiang River Basin.
      Methods This study used MODIS NDVI images in 2001, 2006, 2011, and 2016, and auxiliary data, including the map of geology in Guangxi province, land use data, the map of geomorphological and SRTM DEM.The spatial information of rocky desertification and analyzed the dynamic characteristics of rocky desertification in Xijiang River Basin were extracted by GIS and RS technologies.The information of rocky desertification was extracted by the method of human-computer interaction analysis.The Fractional Vegetation Coverage was the grading standard of rocky desertification, which can be divided into slight, moderate and severe.
      Results 1) From 2001 to 2016, the area of rocky desertification in the Xijiang River Basin decreased from 18.06% to 7.34%, and the decline was increasing.The decline reason of rocky desertification was related to the treatment of rocky desertification and the migration of population.In addition, levels of rocky desertification structure showed pyramidal shape, the area of rocky desertification decreases with the increase of grade.2) Rocky desertification was concentrated in the central and western regions of Xijiang River Basin, which accounted for 87.72% of the total area of rocky desertification in this area.The reduction rate of rocky desertification in the Guihe River and Zuo River basin increased at the beginning of the studied period, and then decreased.In other sub-basins, the reduction rate of rocky desertification reached the maximum between 2011 and 2016.3) The essence of rocky desertification evolution was a process of the mutual transfer between different levels of rocky desertification, and the low-grade rocky desertification was easily transferred to the adjacent-grade.In this study, rocky desertification was gradually transferred to low-grade.In the areas of serious rocky desertification, the ecological environment has deteriorated and was hard to be restored.On the other hand, areas with serious rocky desertification were usually at the top of the hill, where there was usually no way to reach, thus this increase the difficulty of governance.
      Conclusions  The dynamic characteristics of rocky desertification in Xijiang River Basin shows that the treatment of rocky desertification of Xijiang River Basin in Guangxi presented positive influence, but the improvement and deterioration of rocky desertification exists simultaneously, therefore, it is necessary to strengthen the monitoring of it and optimize the comprehensive treatment measures of it in the basin.This study may provide references for further strengthening the monitoring of rocky desertification and optimizing control measures of it in Xijiang River Basin.

       

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