Faculty of Environmental Sciences and EULA Chile Center, Department of Territorial Planning, University of Concepción, Concepción, Chile.
Department of Water Resources, CHRIAM Water Center, University of Concepción, Concepción, Chile.
Sci Total Environ. 2019 Feb 15;651(Pt 1):1517-1533. doi: 10.1016/j.scitotenv.2018.09.237. Epub 2018 Sep 19.
Freshwater systems are subjected to multiple anthropogenic stressors and natural disturbances that act as debilitating agents and modifiers of river systems, causing cumulative and synergistic effects that deteriorate their health and result in watershed vulnerability. This study proposes an easy-to-apply spatial method of watershed vulnerability evaluation using Geographic Information Systems (GIS) in the Andalién River watershed, located in the Chilean mediterranean. A watershed vulnerability index (WVI) based on three sub-indices - anthropogenic stressors, environmental fragility and natural disturbances - was developed. To determine the index grouping weights, expert surveys were carried out using the Delphi method. We subsequently normalized and integrated the factors of each sub-index with relative weights. The ranges of each thematic layer were re-classified to establish vulnerability scores. The watershed was divided into three sections: headwaters zone, transfer zone and depositional zone. The watershed vulnerability index showed that 41% of the watershed had very low vulnerability and 42% had medium vulnerability, while only 1% - in the depositional zone - had high vulnerability. A one-way ANOVA was carried out to analyze the vulnerability differences among the three sections of the watershed; it showed significant differences (F (2, 16) = 8.15: p < 0.05). The a posteriori test showed differences between the headwaters and depositional zones (Tukey test, p = 0.005) and between the transfer and depositional zones (Tukey test, p = 0.014). To validate the WVI, water quality was measured at 16 stations in the watershed; there was a significant correlation between vulnerability level and NO levels (r = 0.8; p = 0.87; α = 0.05) and pH (r = 0.8; p = 0.80; α = 0.05). The WVI showed the cumulative effects of multiple stressors in the depositional zone of the watershed. This is the first study to evaluate and validate non-regulated watershed vulnerability with GIS using multiple anthropogenic and natural stressors.
淡水系统受到多种人为胁迫和自然干扰的影响，这些因素削弱了河流系统的功能，并改变了其结构，导致累积和协同效应，从而使其健康状况恶化，并使流域变得脆弱。本研究提出了一种易于应用的基于地理信息系统（GIS）的流域脆弱性评价空间方法，该方法应用于智利地中海地区的安第连恩河流域。本研究开发了一种基于三个子指数（人为胁迫、环境脆弱性和自然干扰）的流域脆弱性指数（WVI）。为了确定指数分组权重，采用德尔菲法进行了专家调查。随后，我们对各子指数的因素进行了归一化和综合，并用相对权重进行了调整。对每个专题层的范围进行了重新分类，以建立脆弱性得分。流域被分为三个部分：源头区、传输区和沉积区。流域脆弱性指数表明，流域的 41%为极低脆弱性，42%为中脆弱性，只有 1%——在沉积区——为高脆弱性。进行了单因素方差分析（ANOVA）以分析流域三个部分的脆弱性差异；结果表明存在显著差异（F (2, 16) = 8.15：p < 0.05）。事后检验表明，源头区和沉积区之间（Tukey 检验，p = 0.005）以及传输区和沉积区之间（Tukey 检验，p = 0.014）存在差异。为了验证 WVI，在流域的 16 个站点测量了水质；脆弱性水平与 NO 水平（r = 0.8；p = 0.87；α = 0.05）和 pH 值（r = 0.8；p = 0.80；α = 0.05）之间存在显著相关性。WVI 显示了流域沉积区多种胁迫因素的累积效应。这是首次使用 GIS 评估和验证非监管流域脆弱性的研究，该研究考虑了多种人为和自然胁迫因素。
