Spatiotemporal analysis of mangrove cover change and future projections in West Sumatra and Northern Java

Multi-temporal satellite imagery provides critical insights into mangrove cover dynamics and supports coastal management. This study examined changes in mangrove cover (1990–2023) and mid-century projections across six Indonesian regions: Pariaman (West Sumatra) and Indramayu, Brebes, Pemalang, Surabaya, and Madura Island (Northern Java). Landsat and Sentinel-2 imagery were processed using Google Earth Engine (GEE) to derive historical mangrove maps. Future projections were generated using a cellular automata–artificial neural network (CA–ANN) approach implemented in the MOLUSCE plugin for five sites, while mangrove dynamics on Madura Island were projected using a Random Forest (RF) probability-based model in GEE. Results show clear spatial and temporal variability in mangrove cover. Mangrove cover declined slightly in Pariaman (–1.77 ha; − 0.006 ha yr⁻¹) but may increase by 2055 (+ 0.002 ha yr⁻¹). Indramayu experienced a net gain of 23.32 ha (+ 0.017 ha yr⁻¹) but is projected to lose 6.63 ha (–0.006 ha yr⁻¹). Brebes expanded substantially by 627.86 ha (+ 0.022 ha yr⁻¹) and is expected to remain stable, whereas Pemalang showed only minor historical gain (+ 1.16 ha) yet could decline by 54.8 ha (–0.042 ha yr⁻¹). Surabaya increased by 829.09 ha (+ 0.022 ha yr⁻¹) but may lose 113.35 ha by 2052 (–0.003 ha yr⁻¹). Madura recorded the largest gain (+ 2,209.73 ha; +0.024 ha yr⁻¹) with a slight projected decline (–0.001 ha yr⁻¹). These projections are scenario-based representations of likely directional change and should not be interpreted as deterministic forecasts.