The right-branch entrance section of Baguazhou implements the full-section concrete soft mattress project.However，Baguazhou right branch is the main branch，with deep water，rapid currents，and complicated terrain changes，so the full-section layout construction in the riverbed is difficult.In order to illustrate the application effect of the soft mattress in the project，this paper uses the multi-beam bathymetry system to collect underwater topographic data in the project area many times and detects the quality of the soft mattress layout through the multi-beam effect map.Furthermore，the paper uses geographic information system (GIS) spatial analysis technology to quantitatively analyze the riverbed changes in the project area in different periods，so as to better grasp the effect of project remediation and operation.The results show that after the completion of the project，the riverbed of the project has changed from scouring to silting，and the maximum siltation range can reach 7.87 m.The project prevents the further expansion of the entrance section.After the severe flood in 2020，the overall siltation volume and siltation area of the project riverbed continue to increase，with the siltation area ratio increasing from 66.6% to 83.9% and the siltation volume increasing from 414，000 m3 to 545，000 m3.The full-section soft mattress project is running stably and has played a role in engineering protection.