Dynamics of changes in lake volume and surface area using multi-source geospatial data

Geospatial technology has advanced significantly, with modern sensors installed on satellites, terrestrial geodetic survey tools, and aerial devices. These developments allow for the integration of old topographic maps, satellite geospatial data, and bathymetric measurements to study the dynamics of lake volume and surface area. Testing was conducted on Lake Singkarak, a tectonic lake in West Sumatra, Indonesia. The main objective of this study is to monitor the dynamics of changes in the volume and surface area of Lake Singkarak from 1883 to 2023 using multi-source geospatial data. The Dutch East Indies topography-bathymetry (1883) map and the DTM/bathymetry (2023) data were used. All of the data were aligned to a similar map system, namely the horizontal datum (WGS 1984), the vertical datum (EGM 2008), and the projection system (UTM). The DTM/bathymetry (1883) model was extracted based on digitization, and then 3D visualization was performed. The DTM/bathymetry (2023) model was extracted by integrating the latest DTM and field measurements. The latest DTM was obtained from the DTM/bathymetry (2017) (integration of field measurement with satellite imagery 2017), which was then updated with the time-series vertical deformation (2017-2022). After that, the latest DTM was integrated with the field measurement (2023) data to obtain the DTM/bathymetry (2023). A comparison of the 1883 and 2023 models reveals an increase in volume by 2.64 billion m3, a change in the addition of perimeter of 4,509 km, and a change in the decrease in surface area of 1.14 km2. The major earthquake and tsunami in Lake Singkarak in 1926 most likely caused these changes. The results of this modeling can be used for policies in regional planning and disaster mitigation in Lake Singkarak.