Abstract Quantifying bacteria fluxes and contaminants from the point and nonpoint sources in a watershed are important for the management of water quality and safeguard public health. Therefore, the appropriate characterization of bacteria from different sources is necessary for understanding of fate and transport of bacteria in watersheds. However, it is challenging to simulate the effects of pH on bacteria, such as Escherichia coli (E. coli) in the original version of Soil and Water Assessment Tool (SWAT). This study aimed to augment SWAT-bacteria module to evaluate the potential effect of pH on E. coli concentrations. We modified SWAT-bacteria module to incorporate pH factor and to check E. coli observations from four sites of Athabasca River Basin. The modified SWAT-bacteria model demonstrated a linear relationship between observed and simulated daily E. coli data with R2 values found between 0.70 to 0.80; NSE: 0.59 to 0.68; PBIAS: 7.94% to 17.85% during calibration for all monitoring sites (2010-2012). While during the validation (2013-2014) the performance statistics found to be: R2: 0.59 to 0.72; NSE: 0.55 to 0.66; PBIAS: 10% to 22%. The results of the sensitivity analysis confirmed that pH is one of the most significant fate factors of E. coli. The modified SWAT-bacteria module provides an improved estimate of E. coli concentration from the river basin. This study contributes new insight to E. coli modelling. Therefore, the modified SWAT-bacteria model could be a powerful tool for the future regional to global scale model of E. coli concentrations thus significantly contribute for the application of effective river basin management.

中文翻译：

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用于评估 pH 值对阿萨巴斯卡河流域大肠杆菌归宿和运输影响的修正水文模型

摘要 量化流域中点源和非点源的细菌通量和污染物对于水质管理和保障公众健康非常重要。因此，对不同来源细菌的适当表征对于了解流域中细菌的归宿和运输是必要的。然而，在原始版本的土壤和水评估工具 (SWAT) 中模拟 pH 值对细菌的影响具有挑战性，例如大肠杆菌 (E.coli)。本研究旨在增加 SWAT-细菌模块，以评估 pH 值对大肠杆菌浓度的潜在影响。我们修改了 SWAT-细菌模块以纳入 pH 因子并检查来自阿萨巴斯卡河流域四个地点的大肠杆菌观察结果。修改后的 SWAT 细菌模型证明了观察到的和模拟的每日大肠杆菌数据之间存在线性关系，其中 R2 值在 0.70 到 0.80 之间；NSE：0.59 到 0.68；PBIAS：校准期间所有监测站点的 7.94% 至 17.85%（2010-2012）。而在验证期间（2013-2014）发现的性能统计数据为：R2：0.59 至 0.72；NSE：0.55 到 0.66；PBIAS：10% 到 22%。敏感性分析的结果证实，pH 是大肠杆菌最重要的归宿因素之一。修改后的 SWAT 细菌模块提供了对来自河流流域的大肠杆菌浓度的改进估计。这项研究为大肠杆菌建模提供了新的见解。因此，修改后的 SWAT-细菌模型可能成为未来大肠杆菌区域到全球尺度模型的有力工具。