Due to oil and gas exploitation, offshore oil and gas platform may experience subsidence. Continuing subsidence may deform the platform infrastructures, adding the risk for any failure on the platform objects. The failure means disaster. Therefore the subsidence information is mandatory for risk assessment and safety requirement. Repeatedly or continuous monitoring of accurate positions on the platform by using global navigation satellite system global positioning system (GNSS GPS) technology may reveal the changing of even small positions which are representing subsidence on the platform. This chapter will be deeply discussed on the use of GNSS GPS technology for offshore oil and gas platform subsidence monitoring, especially in Indonesia, the archipelago country where long baseline between reference station in the land and monitoring station at the sea slightly exists. The capability and especially the high performance of this technology on deriving subsidence information along with data sample of long baseline will be highlighted.
Part of the book: Multi-purposeful Application of Geospatial Data
Land subsidence by definition is the lowering of ground level from certain elevation references. The rates of subsidence can commonly vary between 1 and 20 centimeters per year and even more in certain places. Subsidence produces impacts such as infrastructure damage, problems with drainage, wider expansion of flood water, as well as tidal inundation (flooding by sea water at coastal areas experiencing land subsidence). These impacts are quite costly. All this is disastrous. In a number of regions of Indonesia, land subsidence and negative impacts in the shape of flooding and tidal inundation clearly exist. In Jakarta and Bandung we can see that the subsiding areas close to rivers frequently suffer from flooding. Tidal inundation is a regular feature at subsiding coastal areas such as Jakarta, Blanakan, Semarang, and Demak. Since these negative impacts are clearly formed a disaster while mitigation and or adaptation is still a big homework, in this case for better adaptation and mitigation in the future, understanding deeply the correlation of land subsidence and flooding is necessary as discused in this chapter. We conclude that the correlation is quite tremendous and indeed producing a disaster.
Part of the book: Natural Hazards