This study evaluated the influence of different land-cover types on the overall water quality of streams in urban areas. To ensure national applicability of the results, this study encompassed ten major metropolitan areas in South Korea. Using cluster analysis, watersheds were classified into three land-cover types: Urban-dominated (URB), agriculture-dominated (AGR), and forest-dominated (FOR). For each land-cover type, factor analysis (FA) was used to ensure simple and feasible parameter selection for developing the minimum water quality index (WQImin). The chemical oxygen demand, fecal coliform (total coliform for FOR), and total nitrogen (nitrate-nitrogen for URB) were selected as key parameters for all land-cover types. Our results suggest that WQImin can minimize bias in water quality assessment by reducing redundancy among correlated parameters, resulting in better differentiation of pollution levels. Furthermore, the dominant land-cover type of watersheds, not only affects the level and causes of pollution, but also influences temporal patterns, including the long-term trends and seasonality, of stream water quality in urban areas in South Korea.

中文翻译：

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使用水质指数评估土地覆盖对大都市区河流水质的影响

本研究评估了不同土地覆盖类型对城市地区河流整体水质的影响。为确保结果在全国范围内的适用性，本研究涵盖了韩国的 10 个主要大都市区。使用聚类分析，流域被分为三种土地覆盖类型：城市主导 (URB)、农业主导 (AGR) 和森林主导 (FOR)。对于每种土地覆盖类型，都使用因子分析 (FA) 来确保简单可行的参数选择，以制定最低水质指数 (WQImin)。化学需氧量、粪便大肠菌群（FOR 的总大肠菌群）和总氮（URB 的硝酸盐-氮）被选为所有土地覆盖类型的关键参数。我们的结果表明，WQImin 可以通过减少相关参数之间的冗余来最大程度地减少水质评估的偏差，从而更好地区分污染水平。此外，流域的主要土地覆盖类型不仅影响污染水平和原因，而且影响韩国城市地区河流水质的时间模式，包括长期趋势和季节性。