基于改进沙丘活动指数的晋北地区土地沙化风险动态分析

Analysis on the dynamics of desertification risk based on improved dune mobility index in north Shanxi Province

土地沙化是全球主要环境问题之一,晋北地区由于地处北方干旱半干旱区,土地沙化是该区经济发展的制约因素之一。文中在传统的沙丘活动指数的基础上,结合地表环境特征对其进行了改进,探讨了基于改进的沙丘活动指数的2001-2012年来晋北地区土地沙化风险的时空分布和变化特征。结果如下:1)改进的沙丘活动指数将气候因子、植被因子和土壤因子纳入考虑。基于改进的沙丘活动指数分析,2001-2012年晋北主要以未沙化风险为主,轻度沙化风险居中,中度沙化风险和重度沙化风险较少。中度以上沙化风险主要集中在西南部的保德县和东北部的南郊区、阳高县和天镇县部分区域。2) 2001-2012年间,晋北沙化土地风险呈现一个持续逆转的态势;呈"明显逆转"和"逆转"的沙化土地风险主要集中在晋西北和左云县、怀仁县、大同县、阳高县等地,呈"发展"和"严重发展"的沙化土地风险则主要集中分布在大同的南郊区和天镇县。研究区重度沙化风险的区域面积在逐渐降低;轻度、中度沙化风险的土地面积在减少,未沙化风险的区域面积在逐渐增加; 3)文中探讨了基于改进的活动沙丘指数的晋北地区土地沙化风险,研究发现该指数在一定程度上能反映整个晋北地区的土地沙化风险特征。但是,该指数也存在一定的不足,人类活动(如国家退耕还林政策)对土地沙化风险会产生一定的影响,未来需要进一步验证指数的合理性。

Desertification is a major environmental problem concerned by all world. Northern Shanxi is located in the east of loess plateau and the temperate semi-arid steppe zone,where the desertification caused by wind erosion is seriously. This research improved dune mobility index introduced by Lancaster,and put forward desertification risk index combined dune mobility index,NDVI and soil erodible K together. The spatial distribution,area and dynamic change of desertification risk of Northern Shanxi were explored based on the desertification risk index. The results indicated: 1) Based on the improved dune mobility index,northern Shanxi province was mainly no desertification risk. The moderate and severe desertification risk could be found in Baode County,Nanjiao District,Yanggao County and Tianzhen Counth. 2) Combining the climate factors and land surface environmental factors together,the desertification risk of research area from 2001 to 2012 exhibited a sustained reversal trend. The 'obvious reversal'and 'reversal 'were mainly concentrated in the northwest of Shanxi and Zuoyun,Huairen,Datong and Yanggao County. The 'development'and 'serious development'were mainly concentrated in the Datong Nanjiao District and Tianzhen County. 3) The improved dune mobility index revealed the relationship between climates,land surface environment and desertification risk. However,human activities such as afforestation also impacted the desertification risk. The rationality of improved dune mobility index should be validated in future.