EFEK AKURASI DAN GEOMETRIK SISTEM TINGGI DIGITAL ELEVATION MODEL (DEM) TERHADAP PEMODELAN BAHAYA BANJIR ROB DI JAKARTA

Abstract

The research aims to analyze the effect of DEM for accuracy and geometric height systems in regard with the results of tidal flood hazard modeling in Jakarta by comparing the modeling results from several DEM data that have different accuracy and by comparing the modeling results between global geoid datum and local datum refer to sea-level height. The high-accuracy DEM LiDAR model was used as a baseline to measure the accuracy between models. The DEMNAS-based model exhibits the result in the flooded area closest to the DEM LiDAR-based model with a ratio of 97%. The open-access Model i.e., DEM SRTM (30 m), DEM TanDEM-X (60 m), and DEM AW3D (30 m), shows a flooded area ratio about 5% - 48% with respect to DEM LiDAR-based model. The comparison between the model indicated a positive correlation between the vertical accuracy and spatial resolution of DEM with the accuracy of the tidal flood hazard model in Jakarta. Model using global geoid datum EGM2008 shows an inundated area less than 30% with respect to the inundated area from model using the Highest Astronomical Tide (HAT) tidal datum. The model validation shows the HAT tidal datum have optimum accuracy. Moreover, the HAT model provides a clear result that shows actual inundation points compared to other vertical datums. Furthermore, the comparisons between these models have been carried out to analyze the effect of model accuracy in regard to the results of the tidal flood risk assessment. The effect of low-accuracy DEM-based model exhibit the number of exposed populations about 2.2 – 54.0 and value of economic loss about 1.9 – 37.6 less times than the risk assessment using DEM LiDAR-based model.