As an important water source and a critical component of the eastern route of the South-to-North Water Transfer Project, Shaobo Lake is vulnerable to sudden water pollution incidents, which could jeopardize water supply security. This study took Shaobo Lake as the research object, a two-dimensional hydrodynamic mathematical model, coupled with a convection-diffusion model was established to simulate the spatial and temporal dispersion patterns of hypothetical sudden pollution incidents under various scenarios. The simulations considered multiple combinations of flow directions, pollution sources, pollutant concentrations and leakage durations, particularly in flood season and water diversion period. The result showed: When the lake flows from south to north with a continuous pollutant source leaks at upstream of the lake, the scenario leads to more severe contamination than others with equivalent total pollutant loads, exhibiting a larger maximum contaminated area (8.4~64.9km2) and prolonged retention time (18~138h); Under various conditions, there exists a positive correlation between the maximum contaminated area in Shaobo Lake and the pollutant retention time, with a Pearson correlation coefficient of 0.954. The research results can provide valuable insights for the planning of water diversion and transfer engineering within South-to-North Water Transfer successor project and for improving emergency management of sudden water pollution incidents in lake regions.