Pemantauan Penurunan Muka Tanah Kota Semarang Tahun 2016 Menggunakan Perangkat Lunak Gamit 10.6

Abstract

In the last 30 years, Semarang city experienced tidal flood. One of the major causes of this tidal flood disaster is land subsidence. Land subsidence inflict hydrological landscape or sea level is higher then the surrounding land. In Indonesia, research about this phenomenon had been conducted in various city, such as Jakarta, Bandung and Surabaya. The excessive extraction of ground water, mining activity, tectonic activity, soil characteristic and also overburden on the land surface are the major causes of land subsidence. In this research data colected using GPS static measurement method. There are 7 observation points which are spread throughtout Semarang city. GPS observation carried out with a duration of 6-7 hours. The GPS data then processed using radial method by GAMIT 10.6 software. The data obtained from GAMIT processing are coordinate value and standard deviation from each observation point. The value of land subsidence obtained by comparing the height value on previous measurement and height value on present measurement. The result of this research is value of land subsidence in Semarang city on 2016 with subsidence value range from 1.33 cm to 34.9 cm. This research also obtained the velocity rate of land subsidence from 2013-2016 with variation range from 2.07 cm/year to 17.04 cm/year. The highest velocity rate of land subsidence was found in the North and East Semarang. The value in economic losses to the effect of tidal flood from settlement sector amounted to idr. 545.985 billion and from infrastructure sector idr. 70.466 billion