Land Subsidence Survey and Policy Development in Pantai Mutiara, Jakarta Bay, Indonesia

The coastal flooding caused by land subsidence is one of major social problems in the coastal area of Jakarta bay, Indonesia. To develop a land subsidence response planning, 3D topographic survey is conducted by using the Terrestrial LIDAR and GPS in Pantai Mutiara. The Terrestrial LIDAR survey results show that the survey site has mean elevation of -0.31m with the highest elevation of 0.31m and lowest -0.99m. Considering that A.H.H.W. (Approximate Highest High Water) is 0.51m, many areas of the survey site are lying below the A.H.H.W. The subsidence happened from 1994 to 2012, subsided about 1.8m and the average rate of about 0.095m. The last stand which keeps the area from flooding and inundation is the dikes built around the area. Although the dikes are still functioning, the heights of the dikes are getting lower and uneven due to subsidence and partial reconstruction. We can conclude that flooding vulnerability of this area depends on the height of the dikes. In order to develop practical policies, we make the distribution maps, expected time of dike flooding, height and cost of dike heightening, through considering land subsidence rate, sea level rising rate, storm surge height and A.H.H.W.