The risk of sudden water pollution is one of the biggest obstacles to ensuring the safety of river basin water environments. While external pressure factors such as illegal discharge have been extensively studied with regard to their impact on the risk of sudden pollution, the influence of the river network topology has received limited attention. To fill this gap, extensive computational experiments were conducted in this study to investigate the effects of river network topology on the potential risk of sudden pollution. Based on the real-world characteristics of dendritic river networks, we used optimal channel networks to generate various river network topologies, represented by seven indicators that encompass morphology, connectivity, and structure. The water quality model simulated the spatial and temporal responses of the samples to a wide range of sudden pollution scenarios, and quantified the associated risk of sudden pollution using three proxy indicators: the maximum standard-exceeding multiple, proportion of standard-exceeding river length, and duration of exceedance. The results showed that among the seven indicators, the average outlet path (Do) and geometric fractal dimension (Dg) had a significant impact on risk. This is because network topology alters hydrological signatures such as discharge, velocity, and travel time. Moreover, multi-group analysis of structural equations revealed that the aspect ratio influences the impact of structural and connectivity indicators on risk by modulating pollution range and concentration. This study revealed the topological factors of the risk of sudden water pollution in dendritic river networks, emphasizing the regulatory role of topology in potential sudden water pollution risk and providing valuable insights for river management and planning.

中文翻译：

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深入了解河网拓扑结构对突发污染风险的影响


突发水污染的风险是确保流域水环境安全的最大障碍之一。虽然非法排放等外部压力因素对突发污染风险的影响已被广泛研究，但河网拓扑的影响受到的关注有限。为了填补这一空白，本研究进行了广泛的计算实验，以调查河流网络拓扑对突发污染潜在风险的影响。根据树枝状河流网络的真实特征，我们使用最佳渠道网络来生成各种河流网络拓扑，由包含形态、连通性和结构的七个指标表示。水质模型模拟了样本对各种突发污染情景的时空响应，并使用最大超标倍数、超标河长比例和超标持续时间 3 个代理指标量化了突发污染的相关风险。结果表明，在 7 个指标中，平均出口路径 （Do） 和几何分形维数 （Dg） 对风险有显著影响。这是因为网络拓扑会改变水文特征，例如流量、速度和行驶时间。此外，结构方程的多组分析表明，纵横比通过调节污染范围和浓度来影响结构和连通性指标对风险的影响。 本研究揭示了树枝状河网突发水污染风险的拓扑因素，强调了拓扑结构在潜在的突发水污染风险中的调节作用，为河流管理和规划提供了有价值的见解。