近年来，珠江三角洲地区咸潮灾害频发，区域供水安全受到威胁，快速、准确地预测咸潮上溯距离对潮汐影响河段取水口优化布置具有重要意义。基于盐度对流扩散方程，推求河口咸潮上溯距离与径流的理论关系并通过构建珠江口水动力-盐度模型，分析咸潮上溯对径流变化的响应特征，提出磨刀门咸潮上溯距离与径流响应模型，继而比较不同咸潮上溯半经验模型在相同水文条件下的应用差异性，评估不同预测模型在磨刀门的适用性。结果表明：在不同的流量动力组合下，珠江口咸界均呈现S形分布特征。咸潮上溯距离L与上游径流量Q在理论上呈现幂指函数关系，利用半经验模型预测磨刀门的咸潮上溯距离是可行的。Savenije模型和L-Q响应模型较好地考虑了实际地形和动力特征的影响，并且模型的计算精度和效率高，可实现磨刀门咸潮上溯距离的快速预测。

Severe salt intrusion has occurred in Peal River Estuary in recent years. It deteriorates water supply quality in the surrounding regions. Rapid and accurate prediction of salt intrusion length is of great significance for optimizing the layout of water intake in river sections. The theoretical relationship between salt intrusion length and runoff was inquired based on the salt conservation equation. And the hydrodynamic-salinity model was established to analyze the response characteristics of salt intrusion to runoff. Then the response model of salt intrusion length and runoff in Modaomen was proposed. Different semi-empirical models are contrasted under the same hydrological conditions to investigate the applicability in the Modaomen estuary. The results show that the salinity boundary presents an S-shaped distribution under different flow combinations. The salt intrusion length L and the upstream runoff Q present a power-exponent function relationship in theory. It is available to predict the salt intrusion length by using semi-empirical models. The conclusion shows that Savenije model and L-Q model perform well, the variation of the real landform and the characteristics of power are taken into account in the model. Moreover, the models are of high efficiency and accuracy, and can be used as a rapid assessment tool in salinity disaster of Modaomen estuary.