Analyzing mangrove forest area changes in coastal zone of Langsa City using landsat imagery

Abstract

Mangrove forest is the most well known in Langsa City. Mangrove forest has high productivity and rich of biodiversity. However, the mangrove area has decreased in quantity. It caused by human activities (anthropogenic factors) and natural conditions. Aims of this research are to map the spatial distribution of mangrove forest in Langsa City, analyze the changes occurring mangrove area, and identify the factors that leading to the changes. Landsat 5 and Landsat 8 OLI images are selected to represent data with multi temporal images (1996, 2006, 2016, and 2018). This study used the maximum likelihood classification on multispectral data. The result of the research showed the accuracy of Landsat 8 OLI images in 2018 was 62.50%. Mangrove area changes during three periods of observed data, i.ehas decreased to 419.04 ha in 1996-2006, increase to 459.76 ha in 2006-2016, and decreased 330.57 ha in 2016-2018. These changes were generally caused by anthropogenic factors such as logging, garbage buildup, over function of mangrove to café, bridge and settlement. On the other hand, natural factors did not caused the change. Natural factors value in research location are accepted by mangrove growth requirements, i.e water pH was 7.8, temperature was 34°C, salinity was 33.03, and DO (Dissolved Oxygen) was 5.28.