Based on the linear variation assumption of the substance concentration, a water quality model is reconstructed, and an early warning model coupled with the river network hydrodynamics and water quality for conventional pollutants and conservative substances is further developed. This paper proposes a new method for calculating the early warning of conventional sudden water pollution accidents, and numerical tests under accidental scenarios are carried out to verify the feasibility of the method. Finally, the influencing factors of the early warning index calculation are analysed, the diffusion errors under two assumptions are compared, and the following conclusions are obtained: (a) the spatial differences in the calculation results of the early warning indexes are mainly caused by the transport path and speed of the accidental pollutants in the river network and the background concentration of the accidental pollutants at sensitive receptors; (b) The numerical diffusion error and the attenuation effect during the transport process of the substance brought by the linear variation assumption is smaller than those of the sufficient mixing assumption; and (c) the linear variation assumption is favourable for prolonging the response time to control the impact from the accident, shortening the duration of the accident impact and decreasing the maximum standard-exceeding multiple of the water quality.

基于物质浓度的线性变化假设，重建了水质模型，并进一步开发了与常规污染物和保守性物质相结合的河网水动力和水质预警模型。本文提出了一种计算常规突发性水污染事故预警的新方法，并在事故场景下进行了数值试验，验证了该方法的可行性。最后，分析了预警指标计算的影响因素，比较了两个假设下的扩散误差，得出以下结论：（a）预警指标计算结果的空间差异主要是由于河网中偶然污染物的传输路径和速度以及敏感受体处的偶然污染物的背景浓度引起的；（b）线性变化假设带来的物质在运输过程中的数值扩散误差和衰减效应小于充分混合假设的数值扩散误差和衰减效应；（c）线性变化假设有利于延长响应时间以控制事故的影响，缩短事故影响的持续时间并降低水质的最大标准超标倍数。（b）线性变化假设带来的物质在运输过程中的数值扩散误差和衰减效应小于充分混合假设的数值扩散误差和衰减效应；（c）线性变化假设有利于延长响应时间以控制事故的影响，缩短事故影响的持续时间并降低水质的最大标准超标倍数。（b）线性变化假设带来的物质在运输过程中的数值扩散误差和衰减效应小于充分混合假设的数值扩散误差和衰减效应；（c）线性变化假设有利于延长响应时间以控制事故的影响，缩短事故影响的持续时间并降低水质的最大标准超标倍数。