Towards Water Hyacinth Identification using Index Vegetation from Sentinel-1 and Sentinel-2 in Selorejo Dam

Abstract Water hyacinths have become a significant issue at the Selorejo Dam in recent years. The invasive nature of this plant and the dam’s location, surrounded by rice fields, make predicting the growth of water hyacinths at the Selorejo Dam challenging. Several studies have applied passive remote sensing satellite technology, such as Sentinel-2A/B, to observe water hyacinth growth as a substitute for in-situ observations, which are limited by time and area coverage. However, considering that rainfall in the Selorejo Dam area can reach up to 3000 mm/year, passive satellites alone may not sufficiently accommodate the need for comprehensive water hyacinth monitoring. The first successful research utilizing Sentinel-1 for monitoring water hyacinths was conducted in 2021 at Vembanad Lake, India. This research addresses the limitations of passive satellites in identifying water hyacinths due to weather conditions. It integrates passive satellite data from Sentinel-2 and active satellite data from Sentinel-1 to provide a more complete identification of water hyacinths in the Selorejo Dam. The results of this research indicate that both Sentinel-1 and Sentinel-2 can differentiate between vegetation and water areas using DPSVIm for Sentinel-1, with an overall accuracy of 0.8, and NDVI for Sentinel-2, with an overall accuracy of 0.84. These findings represent a preliminary step in the process of identifying water hyacinths in the Selorejo Dam.