Budhy Soeksmantono
Segara Anakan is a lagoon located in the western part of Cilacap Regency, Central Java Province. Segara Anakan is separated from the Indian Ocean by Nusakambangan Island, and is surrounded by mangrove areas and muddy plains. Segara Anakan is also the estuary for several rivers on the island of Java, such as the Citanduy River which flows to the west, and other rivers such as Cimeneng and Cikonde. In recent years, Segara Anakan Lagoon has experienced degradation and shrinkage of its water area due to high levels of sedimentation, which is caused by sediment carried by rivers that empty into Segara Anaka. According to data collected by the Citanduy River Basin Center (2012), it is estimated that the amount of sediment entering from the Citanduy River is 8.05 million tons/year, the Cimeneng River 0.87 million tons/year, and the Cikonde River 0.22 million tons/year. Sediment deposition in Segara Anakan causes changes in the lagoon ecosystem and can threaten the diversity of living things in this area, which is also important for supporting the economic activities of the surrounding residents.
This large level of sedimentation can be caused by several things, including is a change in land cover (land cover) in river watershed areas (DAS) that flow into Segara Anakan, especially the Citanduy Watershed. Changes in land cover, especially from tree cover to open land, can have an impact on increasing levels of erosion in an area, which causes high amounts of sediment to be carried by rivers and then deposited into estuaries. This causes a change in the estuary area, in this case Segara Anakan, from water to land. Therefore, a spatial approach is needed to monitor changes in overall land cover in the Citanduy watershed and the Segara Anakan lagoon on a regular basis. Satellite imagery can be used as an effective way of data acquisition and land cover classification for very large areas. This spatial approach can be carried out using Sentinel 1 (radar) and Sentinel 2 (optical imagery) satellite imagery to be able to clearly see land cover changes that occur in the area. To achieve this, this research used three types of observation methods, namely changes in the land cover classification of the Citanduy watershed, land increase (or water shrinkage) in the Segara Anakan area, and visualization of coastline shifts in Segara Anakan and its surroundings.