A Abstractflooding in the kali kamal watershed, tegal alur subdistrict, west jakarta, has recurred throughout the 2020–2025 period, with inundation depths ranging from 20 to over 50 cm. these events were driven by extreme rainfall, river overflow, sedimentation, and tidal backwater effects. while accurate hydraulic modeling is essential for supporting flood mitigation efforts, the use of secondary airborne lidar data in dwg format is constrained by spatial generalization and inadequate representation of riverbed bathymetry. this study aims to evaluate the effectiveness of a spatial fusion method that integrates lidar dwg data, cross-sectional surveys, and ground control points (gcps) to enhance the accuracy of flood modeling using hec-ras 2d. three elevation models were tested: model a (lidar dwg + terrestrial survey + gcp), model b (dem + terrestrial survey + gcp), and model c (dem + gcp). the models were evaluated using the vertical root mean square error (rmsez) and nash-sutcliffe efficiency (nse), while the simulation results were validated against historical flood records from 2020 to 2025. model a yielded the highest accuracy, with an rmsez ranging from 0.080 to 0.129 m and an nse of 0.999, successfully satisfying the geometric accuracy standards established by the indonesian geospatial information agency (big). furthermore, the hec-ras 2d simulation utilizing model a demonstrated strong agreement with historical inundation patterns. the findings suggest that the spatial fusion method effectively overcomes the limitations of secondary lidar dwg data, generating a highly representative elevation model that supports robust hydraulic modeling and urban flood mitigation planning.