Abstract
A lagoon is a natural feature formed at the mouth of a river due to the dynamics of river sedimentation, currents, vertical deformation, waves, and tides. Lagoons are dominated by soft soil, so their topography is dynamic. Segara Anakan Lagoon (SAL) is an area that experiences dynamic topography caused by rapid sedimentation. Changes in the dynamics of the delta topography can be tracked in the past with the Digital Terrain Model (DTM) time series extracted from the latest DTM, vertical deformation, and sedimentation data. The observation period was 1978–2021. This study aims to model topography dynamics (1978–2021) in SAL according to DTM, vertical deformation, and sedimentation data. This dynamics topography modeling uses (1) parameters of sedimentation rate and volume obtained from river basin center – Balai Besar Wilayah Sungai (BBWS) 2012, (2) DTM 2021 extracted from ALOS-2 (2017) and integrated with vertical deformation from Sentinel-1 (2017–2021) using the Differential Interferometry Synthetic Aperture Radar (D-InSAR) method. The DTMs (1978, 1991, 2001, and 2010) are extracted using a geospatial forensics approach based on topography modeling of DTM 2021, vertical deformation (2017–2021), and rapid sedimentation data. We use the sediment rate entering SAL from the Citanduy River (8.05 million tons/year), Cimeneng River (0.87 million tons/year), and Cikonde River (0.22 million tons/year), with a total sediment supply of 9.14 million tons/year. The DTM 2021 has a spatial resolution of 1 m and has been validated in its vertical accuracy test (+17.6 cm) and its height difference test (~0 m) with a confidence level of 95 % (1.96 σ). The average vertical deformation value is –0.0240 to –0.0320 m. The results obtained are dynamics topography information (1978–2021). The DTMs (1978–2021) visualize dynamics topography changes in SAL. They are carried out by checking the dynamics of shoreline changes and cross-section profiles to determine the suitability of shapes and patterns (lagoon and delta). Sedimentation is the most significant parameter that influences the topography dynamics in SAL.