基于ESAI的黄土高原荒漠化风险评估

[目的]对黄土高原荒漠化风险进行评估,为黄土高原生态环境的恢复、建设和保护提供科学依据。[方法]通过收集黄土高原的地形、气候、植被、土壤以及社会经济等方面的数据,借助RS和GIS平台,实现黄土高原荒漠化风险评估的空间化和数字化,在此基础上分析荒漠化的成因,构建荒漠化风险评价指标体系,建立基于环境敏感性区指标(ESAI)的荒漠化风险评估模型,分析荒漠化风险程度的空间格局,探索黄土高原不同区域荒漠化形成的主要原因。[结果](1)基于土壤、气候、植被3种要素的环境敏感区生物物理指标显示:黄土高原大约1/4的区域(25.2%)为高风险区,属于严重荒漠化,几乎2/3的区域(62.8%)是轻微荒漠化,11.5%的地区为潜在荒漠化,只有0.5%的地区无荒漠化现象;(2)加入人类诱发因素后,改变了黄土高原荒漠化风险区的原有格局。其中,极低、低度和极高度敏感区减少了5.6%,1.1%和3.8%;与此同时,较低和较高度敏感区增加了4.4%和4.5%。[结论](1)该模型能很好地说明黄土高原荒漠化风险的空间分布格局,其荒漠化程度由西北向东南地区逐渐减弱;(2)人类活动已经在一定程度上打破了长期稳定的自然生态系统,并且缩小了不同程度荒漠化之间的差距。

ESAI Based Assessment of Desertification Risk in Loess Plateau

[Objective] The risk of desertification was evaluated in Loess Plateau to provide scientific basis for the restoration, construction and protection of ecological environment. [Methods] Data of landform, climate, vegetation, soil and other socio-economic data were collected. Spatialization and digitalization were conducted using GIS and remote sensing. Upon which, desertification reasons were analyzed, and evaluation indices and risk assessment model were framed based on index of environmentally sensitive areas. [Results] (1) According to the bio-physical index in the framed model, under the scenario only considering natural factors as soil, climate and vegetation, 25.2% of Loess Plateau was determined as high desertification risk area, where desertification was worst; 62.8% and 11.5% of Loess Plateau were determined as moderate and potential desertification risk areas; only 0.5% was considered having no risk. (2) If both natural factors and human interference were considered, risk area changed: coverages of extreme low, low and extreme high risk levels decreased by 5.6%, 1.1% and 3.8%, respectively; whereas, coverages of lower and higher risk levels increased by 4.4% and 4.5%. [Conclusion] (1) The ESAI model can well explain the spatial distribution pattern of desertification risk of Loess Plateau, and the degree of desertification is gradually weakened from the northwest to the southeast. (2) Human activities have upset the long-term evolved stability of the natural eco-system to some extent, and have narrowed the gap between different risk levels of desertification.