1980年以来黄土高原半干旱区乡村人居环境系统脆弱性时序演变——以陕西省佳县为例

Change in vulnerability of rural human settlement in the semi-arid area of the Loess Plateau since 1980:A case study of Jiaxian County, Shaanxi Province

从人地系统脆弱性视角切入,遵循"演变轨迹刻画-阶段情景描绘-演化路径与机理剖析"的逻辑轴线,结合"ground-truthing"质性研究方法,探索了1980年以来以陕西省佳县为代表的黄土高原半干旱区乡村人居环境系统演变历程与路径。主要结论如下:①定量测度了1980-2016年佳县乡村人居环境综合系统及子系统脆弱度值。其中,自然系统脆弱性由干旱主导转向雨涝灾害主导;21世纪以来,居住系统脆弱性全面减轻,支撑系统脆弱性反弹加剧;近10 a,社会系统脆弱性逐渐减轻,人类系统已走向重度脆弱等级,综合脆弱性停滞于中度脆弱等级。②提出了乡村人居环境系统脆弱性情景转化阈值规则,界定了顽固脆弱、不受控制的脆弱、可控的脆弱、稳定健康、易变的系统等5类脆弱性情景。案例区脆弱性演变经历4个阶段,但徘徊于顽固脆弱的系统与不受控制的脆弱性系统情景之间。③建构了乡村人居环境系统脆弱性阶段性演化动力机制,梳理了5大子系统脆弱性阶段性演化路径,提炼了涉及气候变化、城市化扰动、市场变化、政策干预及农户行为适应等5大驱动因素的20件关键影响事件。

From the perspective of human-environmental system vulnerability and following the steps of depicting evolution trajectory-describing the situations-analyzing evolution paths and mechanisms, combined with the ground-truthing method, this study explored the change of rural human settlement in the semi-arid area of the Loess Plateau represented by Jiaxian County of Shaanxi Province. The main results are as follows: 1) The quantitative assessment of the vulnerability of rural human settlement synthetic system and subsystems in Jiaxian County from 1980 to 2016 shows that, the natural system has changed from vulnerable to droughts to vulnerable to floods. Since the 21 st century, vulnerability of the housing system has been reduced, while the vulnerability of the supporting system has been aggravated. In the past decade, the vulnerability of the social system has been gradually reduced, and the human system has moved to a severe level of vulnerability.Composite vulnerability remained at moderate levels. 2) The study defined five types of vulnerability situations,including persistent vulnerability, uncontrolled vulnerability, controllable vulnerability, stable healthy state, and volatile systems, and proposed the thresholds for crossing vulnerability types. Vulnerability in the case area has gone through four stages between persistent vulnerability systems and uncontrolled vulnerability systems. 3) The research not only reconstructed the dynamic mechanism of the gradual change of vulnerability of the rural human settlement and identified the evolutionary path of vulnerability of five subsystems, but also extracted 20 key influencing events involving five driving factors-climate change, urbanization disturbance, market change,policy intervention, and farmers’ behavioral adaptation. In the end, the article puts forward some suggestions on how to improve rural human settlement and facilitate the rural rehabilitation and revitalization.