Improved Performance of Geospatial Model to Access the Tidal Flood Impact on Land Use by Evaluating Sea Level Rise and Land Subsidence Parameters

In the 20th century, climate change caused an increase in temperature that accelerated the rate of sea level. Sea level rise and land subsidence threaten densely populated coastal areas as well as lowlands because they cause tidal flooding. Tidal floods occur every year due to an increase in sea level rise and land subsidence. The lack of information on this phenomenon causes delays in disaster mitigation, leading to serious problems. This study was conducted to predict the area of tidal flood inundation on land use in 2020 to 2035. This research was performed in Pekalongan Regency, as one of the areas experiencing large land subsidence and sea level rise. The research data to be used were tides and the value of soil subsidence, as well as sea level rise. Digital Terrain Model (DTM) was obtained through a topographic survey. Modeling was used for DTM reconstruction based on land subsidence and sea level rise every year. The sea level rise value uses the satellite altimetry data from 1993–2018. A field survey was conducted to validate the inundation model that has been created. Land subsidence was processed using Sentinel-1 Synthetic Aperture Radar (SAR) image data with Single Band Algorithm (SBA) differential interferometry. This study proved that tidal flooding has increased every year where in 2020 it was 783.99 hectares, but with the embankment there was a reduction in inundation area of 1.68 hectares. The predicted area of tidal flood inundation in 2025, 2030 and 2035 without the embankment is 3388.98 hectares, 6523.19 hectares, 7578.94 hectares, while with the embankment in 2035 is 1686.62 hectares. The research results showed that the use of embankments is a solution for coastal mitigation as well as regional planning.