在现有城市洪涝模拟研究中，地表-管网松散耦合难以准确描述水力交换过程，且未来城市下垫面数据难以满足城市尺度精细化模拟需求。为更准确刻画城市化影响下滨江城市洪涝过程，以滨江城市主城区为例，构建水文水动力紧密耦合模型，并结合多引擎城市扩张模拟器预测2025—2040年城市建成区扩张过程，分析不同降雨条件和不同城市化阶段下的管网超载过程与地表淹没响应特征。结果表明：①随降雨重现期增大，溢流持续时间>2 h的溢流节点占比持续上升，在100 a一遇重现期下达79.17%，水深>1 m的淹没面积从1 a一遇的4.38 km²增至100 a一遇的28.05 km²。②未来城市扩张模式下，2024年模拟建成区与实际值相对误差仅为0.267%，Kappa系数为0.869；预测2025—2040年城市建成区面积将从95.485 km²增至131.453 km²，扩张模式以边缘式扩张为主并呈多元化发展趋势。③地表淹没程度随城市化进程持续加剧，1 a一遇重现期下总淹没面积由14.23 km²增至22.98 km²，50 a一遇时水深>1 m的淹没面积从2.96 km²增至20.18 km²。研究结果可为城市防洪减灾规划与韧性城市建设提供科学依据。

[Objective] In urban flooding simulation，the loose coupling between surface flow and pipe networks fails to accurately describe bidirectional hydraulic exchange processes，and future urban underlying surface data cannot meet the fine-scale simulation requirements at the urban scale. To address these limitations，this study aims to simulate the pipe network overloading processes and surface inundation evolution under different rainfall scenarios and urbanization stages，providing a scientific basis for flood control planning and resilient city construction in riverside cities. [Methods] A tightly coupled 1D-2D hydrodynamic model was developed by integrating SWMM with LISFLOOD-FP，enabling real-time bidirectional data exchange between the surface and pipe network at a unified time step of 1 second. Three hydraulic exchange processes were considered： overflow from the pipe network to the surface，surface inflow into the pipe network via orifice flow，and weir flow. Design rainfall scenarios with return periods ranging from 1 to 100 years were generated using the Chicago rainfall pattern method with a duration of 120 minutes，and model parameters were calibrated using the comprehensive runoff coefficient as the calibration target. The Multi-engine Urban Expansion Simulator （MUSE） was introduced to simulate urban built-up area expansion from 2026 to 2040，adopting the Neighborhood-constrained Patch Growth Engine （Nei-PGE） and lognormal patch size distribution，with model accuracy evaluated using the Kappa coefficient，Figure of Merit （FoM），and Overall Accuracy （OA）. On this basis，the pipe network operating conditions and surface inundation response characteristics under different rainfall scenarios and future urbanization stages were systematically analyzed. [Results] （1） Model calibration results show that the coefficient of variation remains within ±10% across all return periods，confirming the model’s applicability. As the return period increases，the number of overflow nodes （NON） with overflow duration exceeding 2 hours rises continuously，reaching 79.17% of total nodes under the 100-year return period； the inundation area with water depth exceeding 1 m increases from 4.38 km² under the 1-year return period to 28.05 km² under the 100-year return period. （2） The urban expansion simulation achieves high accuracy，with a relative error of only 0.267% between the simulated and actual built-up area in 2024，a Kappa coefficient of 0.869，FoM of 0.573，and OA of 0.870； the urban built-up area is projected to increase from 95.485 km² to 131.453 km² during 2025-2040，with edge expansion as the dominant pattern alongside diversified internal infilling trends. （3） Under future urbanization scenarios，surface inundation risk intensifies progressively，with total inundation area under the 1-year return period increasing from 14.23 km² in 2026 to 22.98 km² in 2040，and inundation area with water depth exceeding 1 m under the 50-year return period increasing from 2.96 km² to 20.18 km². In contrast，the impact of urbanization on overflow node counts is relatively limited，with maximum NON variation not exceeding 4 nodes across urbanization stages under the same return period，indicating that the existing drainage network has approached saturation. [Conclusions] This study develops an integrated urban flood assessment framework coupling fine-scale hydrodynamic simulation with future urban expansion prediction for riverside cities. The tightly coupled hydrological-hydrodynamic model effectively captures the dynamic bidirectional hydraulic interaction between surface water and the drainage network，while the MUSE-based urban expansion simulation provides high-resolution future land use scenarios for flood modeling across multiple urbanization stages. The results demonstrate that as rainfall intensity increases，overflow nodes with shorter overflow duration progressively transition to longer-duration overflow. Urbanization significantly intensifies surface inundation risk，with shallow inundation areas gradually transitioning to deeper inundation zones as urbanization advances. In contrast，the impact of urbanization on overflow node counts is relatively limited，indicating that the existing drainage network has approached saturation，and that the effects of newly added impervious surfaces are primarily manifested as prolonged overflow duration and increased overflow volume rather than an expanded spatial distribution of overflow nodes.