Pemetaan Perubahan Luasan Padang Lamun Menggunakan Citra Sentinel-2A di Perairan Pulau Harapan dan Pulau Kelapa, Taman Nasional Kepulauan Seribu

Abstract

Lamun merupakan tumbuhan berbunga (Angiospermae) yang dapat ditemukan di pesisir pantai hingga perairan dangkal dan dapat beradaptasi terhadap perairan bersalinitas. Padang lamun memiliki fungsi penting antara lain sebagai habitat biota laut alami dan dapat memperlambat pergerakan arus serta gelombang ke darat. Aktivitas manusia seperti kegiatan perikanan, budidaya, pariwisata dan alih fungsi lahan untuk pembangunan dapat mengakibatkan kerusakan pada lamun yang berakibat pada penurunan luas padang lamun. Penelitian ini bertujuan untuk memetakan sebaran dan perubahan luas lamun di perairan Pulau Harapan dan Pulau Kelapa. Penelitian ini diawali dengan pengambilan data lapang dan pengolahan citra satelit Sentinel-2A berupa preprocessing citra dan koreksi kolom air. Selanjutnya dilakukan klasifikasi maximum likelihood pada citra sentinel-2A akuisisi 22 November 2015 dan 24 April 2021. Hasil klasifikasi citra diperoleh tiga kelas yaitu kelas non lamun, lamun padat, dan lamun sedang. Pada tahun 2015 luas area padang lamun seluas 0,92 km2 dan non lamun 1.58 km2, di tahun 2021 luas lamun seluas 0,70 km2 dan non lamun 1.79 km2. Terjadi perubahan luas area lamun menjadi non lamun seluas 0.52 km2 dan area non lamun yang menjadi lamun seluas 0.30 km2. Nilai overall accuracy yang diperoleh sebesar 74.17% sudah memenuhi standar minimal 60% dari Badan Informasi Geospasial.

Seagrass is a flowering plant (Angiospermae) found on the coast in shallow waters and could adapt to salinity waters. Seagrass beds have important functions as a natural habitat for marine organisms and reduce the movement of currents and sea waves into the land. Human activities such as fishing, aquaculture, tourism, and land conversion for development can cause damage to seagrass, resulting in a decrease in the area of seagrass beds. This study was to map the seagrass distribution and detect changes in the seagrass area in the waters of Harapan and Kelapa Islands. This research begins with field data collection and processing of Sentinel-2A satellite imagery, image preprocessing, and water column correction. The next step is the maximum likelihood classification is carried out on the Sentinel-2A image with the acquisition on 22 November 2015 and 24 April 2021. The image classification results obtained are three classes: non-seagrass, dense seagrass, and medium seagrass. In 2015 the area of seagrass beds was 0.92 km2, and non-seagrass areas were 1.58 km2, while in 2021, the area of seagrass beds was 0.70 km2 and non-seagrass fields area was 1.79 km2. There was a changing area of seagrass becoming non-seagrass at about 0.52 km2, and the location of non-seagrass, which became seagrass, is 0.30 km2. The overall accuracy value obtained of around 74.17% already meets the minimum standard of 60% from the Geospatial Information Agency.