The density of mangrove cover is one of the factors that influence changes in shoreline both accretion and abrasion. This study aims to determine the effect of changes in density of mangrove cover on shoreline changes in 1989-2018 in the Coastal Province of Jambi. The method used is the interpretation of Landsat satellite images in 1989, 2000 and 2018 using NDVI (Normalized Difference Vegetation Index) and overlaying images to see shoreline changes and DSAS (Digital Shoreline Analysis System) to calculate the area of change. The results showed that there had been a change in shoreline both accretion and abrasion in several locations that had different mangrove densities in the period 1989-2018. The results showed that accretion occured in 6 locations with an average change of Kota Sebrang 771 m, Tungkal Ilir 240.65 m, Kuala Betara 153.73 m, Mendahara 167.78 m, Kuala Jambi 169.35 m and Nipah 57.3 m, while abrasion occurs at 2 locations with an average change in Sabak Timur -41.8 m and Sadu -36.55 m. Where in the 6 locations that had accretion, mangrove density dominantly was in a close-densed and moderate state and only a few are in a low-densed condition. Meanwhile, the 2 locations that had abrasion were in a moderate state and have a low density mangrove forest.

Abstrak: Penelitian ini mengembangkan suatu bahan ajar berupa lembar kegiatan siswa yang berbasis komunikasi matematis dengan model pembelajaran group investigation. Pengembangan LKS menggunakan model pembelajaran group investigation ini bertujuan untuk melatih kemampuan komunikasi matematis siswa pada materi limit. Model pengembangan yang digunakan adalah 4-D terdiri atas empat tahapan yaitu define, design, develop dan disseminate. Penelitian hanya dilakukan sampai uji coba terbatas pada tahap develop karena waktu yang terbatas. Penelitian ini dilaksanakan di MA Al-Hikmah Merauke pada kelas XII IPA sebagai sampel uji coba terbatas yang berjumlah 12 siswa. Teknik pengumpulan data dengan memberikan angket kevalidan kepada validator untuk mengukur kevalidan produk serta angket kepraktisan kepada guru dan siswa untuk mengukur kepraktisan produk. Analisis data dilakukan dengan menghitung persentase nilai dari angket yang diberikan kepada validator dan responden. Hasil penelitian menunju kan bahwa LKS dengan model pembelajaran group investigation berbasis komunikasi matematis berada pada kriteria valid dan praktis. Produk yang dikembangkan sudah layak digunakan untuk uji coba lapangan dan pembelajaran di sekolah. Abstract: This study developed a teaching material in the form of student’s worksheet based on mathematical communication with the group investigation learning model. The development of student’s worksheet using the group investigation learning model was aimed at training student mathematical communication skills on the limit material. The research model used is 4-D consisting of four stages, namely define, design, develop and disseminate. The research was only conducted until the trial at the develop stage due to limited time. This research was conducted at MA Al-Hikmah Merauke in class XII IPA as a limited trial sample, amounting to 12 students. Data collection techniques was by providing validity questionnaires to validators to measure product validity and practicality questionnaires to teachers and students to measure the practicality of the product. Data analysis was performed by calculating the percentage value of the questionnaire given to the validators and respondents. The results showed that student worksheets with the group investigation learning model based on mathematical communication were in valid and practical criteria. The product developed is suitable for use for field trials and learning in schools.