针对传统Preissmann窄缝法在排水管网明、满流交替模拟中物理机制表征不足、复杂边界适应性差的问题，研究提出了基于Godunov格式的有限体积法的一维水动力数学模型。该模型采用明流和满流两组控制方程组，耦合TPA方法与改进的HLLS黎曼求解器，建立明流、满流及明满交替流统一模拟框架。在此基础上，模型基于特征线方程与真实管道几何参数，提出了交汇节点、调蓄池、控制闸门、泵站出口及河湖等多种复杂边界的处理方法，显著提升了其在管网系统中的适用性。通过树状、环状管网等经典算例验证，模拟结果吻合良好。研究发现基于Preissmann窄缝法与“管道-节点”概化方式的通用软件暴雨洪水管理模型（SWMM），在模拟管网非恒定水流演进时会产生相邻节点水位同步变化的非真实物理现象；而本模型可精准捕捉管道液面非均匀抬升与瞬态波动的水流传播特性，可用于城市排水管网明满流动的精细化模拟。

[Objective] To address the insufficient physical representation and poor adaptability to complex boundaries of the traditional Preissmann slot method in simulating open channel-to-pressurized flow transitions in drainage networks，this study develops a one-dimensional hydrodynamic model using the Godunov-type finite volume method. [Methods] The model employs two sets of governing equations for free-surface and pressurized flows，coupling the Two-Component Pressure Approach （TPA） with an improved Harten-Lax-van Leer with Source term （HLLS） Riemann solver. This establishes a unified simulation framework for open-channel flow，pressurized flow，and mixed open channel-pressurized flow. Accordingly，the model proposes treatment methods for various typical boundaries，including junction nodes，storage tanks，control gates，pump station outlets，and river-lake systems，based on the characteristic line equations and actual pipeline geometric parameters，significantly enhancing its applicability in pipe network systems. The model is validated through classical test cases such as tree-like and looped pipe networks，showing excellent agreement between simulated and expected results. [Result] The study reveals that the widely used SWMM model，which is based on the Preissmann slot method and the “pipe-node” conceptualization approach，produces unrealistic physical phenomena—such as synchronized water level variations at adjacent nodes—when simulating unsteady flow propagation in pipe networks. In contrast，the proposed model accurately captures non-uniform water level rises and transient fluctuation characteristics along pipelines，providing a more realistic representation of flow propagation. [Conclusion] The proposed model is suitable for detailed dynamic simulations of mixed free-surface and pressurized flows in urban drainage networks.