INTEGRASI CITRA UDARA DAN BATIMETRI UNTUK PENYUSUNAN MODEL ELEVASI BELOKAN SUNGAI WONOKROMO

Abstrak

This study aims to develop an accurate elevation model of the meander segment of the Wonokromo River through integrating UAV-based aerial photogrammetry and bathymetric measurements. Flooding in southern Surabaya is strongly influenced by tidal backwater effects and the reduced channel capacity caused by sedimentation and geometric changes in river bends. Therefore, detailed topographic and bathymetric information is essential to support hydrological and hydraulic assessment. Data acquisition was conducted using a UAV that captured 653 images with 20 GCPs and 8 ICPs, while riverbed depths were measured using a 200 kHz echosounder. The photogrammetric workflow included photo alignment, dense cloud generation, DSM/DTM construction, and orthomosaic production, followed by integration with bathymetry corrected to orthometric height using the SRGI geoid model. Accuracy evaluation shows high spatial fidelity, with CE90 of 0.064 m and LE90 of 0.073 m, meeting Class 1 accuracy standards for 1:1,000 scale mapping. The resulting orthophoto has a ground sampling distance of 2 cm and successfully represents detailed morphological features along the river bend. The integrated topobathymetric DEM provides a seamless elevation model from land to riverbed, enabling more precise analysis of flow patterns, erosion–deposition characteristics, and morphological changes in the Wonokromo meander. These results confirm that the integrated dataset is highly suitable for hydromorphological studies and can support flood mitigation planning in the surrounding region.