<p>For reservoirs located in mountainous regions, often referred to as channel-like reservoirs, the dynamics of landslide-generated impulse waves (LGIWs) differ considerably. The LGIW disaster resulted from the Huangtian landslide, which occurred in southwestern China, exemplifies a typical event in such channel-like reservoirs. However, survey data is limited due to the challenges of field observations. For instance, the evolution of LGIWs and the landslide movement process remain unknown. To investigate this practical event, a soil-water coupling model utilizing the Smoothed Particle Hydrodynamics (SPH) method is introduced. The results demonstrate a close alignment with actual observations. Notably, the evolution of the leading wave within the channel-like reservoir reveals significant differences, as the water body transitions from the common three-dimensional spreading propagation characteristic of reservoirs to a unidirectional movement along the river channel. This transition complicates the direct application of empirical formulas derived from conventional physical modeling experiments to wave phenomena in channel-like reservoirs. Moreover, the head velocity of the landslide diverges from its average velocity, offering a more accurate characterization of the landslide’s impact on the water body. The energy conversion coefficient peaks at approximately 15% around the moment the landslide impacts the opposite bank, highlighting the substantial influence of topographic characteristics on the energy conversion process. The analysis also addresses the degree of siltation in the channel following the landslide and its implications for navigation.</p>