Analyzing the vegetation density changes of Serang watershed using satellite imagery data in Kulon Progo district, Indonesia

The Serang watershed, which is one of the main watersheds in Kulon Progo Regency, has experienced land degradation of about 5% of the entire watershed. This study analyzes changes in vegetation around the Serang watershed in 2019 and 2020. The main activity to achieve this goal is vegetation classification using Landsat 8 in 2019 and 2020, which is used to detect changes in vegetation. The Red Band and Near Infrared Band on Landsat 8 are combined to classify vegetation density classes using the Normalized Difference Vegetation Index (NDVI) algorithm. Two methods to validate the classification are field surveys and observations on high resolution images using Sentinel-2. The number of samples for classification validation was 50 samples and was selected randomly. Next, the sample data is compared with the interpretation of the vegetation classification. As a result, 90% of vegetation classification interpretations were validated and these results were used to calculate the percentage change in vegetation. The total area of vegetation density decreased from 2019 to 2020. Classification of vegetation density classes decreased from 40.21% to 39.46%. This percentage, based on the status of the vegetation condition, has changed from moderate vegetation to poor vegetation density.