Analysis of Changes in Density of Mangrove Using Normalized Difference Vegetation Index Algorithm on Sentinel 2A Level 1C (Case Study: Gresik Regency)

Mangrove forests have important values and roles both ecologically and economically in coastal areas. Over time, the area of mangrove forests in Indonesia decreased due to high rates of deforestation. One of the mangrove forests that has decreased in the area is the mangrove forest on the North Coast of East Java. Therefore, monitoring of changes in the density of the mangrove canopy is needed, especially in Gresik Regency. Mangrove ecosystems can be identified using remote sensing technology. To get the density level of the mangrove canopy, it can be done by calculating the Normalized Difference Vegetation Index (NDVI) algorithm on the Sentinel 2A Level 1C satellite imagery in 2016–2019. Based on the results of the study, it was concluded that the dominant mangroves in Gresik Regency in 2016 to 2019 were mangroves with good density, which amounted to 58.66% in 2016; 53.21% in 2017; 45.22% in 2018, and 46.81% in 2019. Then, the mangrove area in Gresik Regency from 2016 to 2019 increased by 22.09% in 2017, then decreased by 1.74% in 2018 and continued to decrease by 8.28% in 2019. The most influential parameter for the density of mangrove canopy is the water pH with a correlation coefficient of -0.733 which shows that the density of mangroves canopy and the water pH has a strong and significant correlation.