<![CDATA[The Upper Ciliwung Watershed plays an important role in regulating the hydrological system of downstream areas, particularly Jakarta, which is highly prone to flooding. Population growth within the Greater Jakarta metropolitan area and land conversion in the Puncak region have reduced the watershed’s capacity to provide water-regulating ecosystem services. This study aims to (1) assess and map water-regulating ecosystem services in the Upper Ciliwung Watershed in 2015 and 2025 and (2) evaluate their dynamics and formulate management recommendations for flood mitigation. The assessment was conducted using a Multi-Criteria Evaluation (MCE) method based on four parameters: slope, Topographic Wetness Index (TWI), Normalized Difference Vegetation Index (NDVI), and soil depth. The study used 30 m resolution SRTM data, Landsat 8/9 imagery acquired in 2015 and 2025, and a 1:50,000-scale soil map produced by the Indonesian Center for Agricultural Land Resources Research and Development. Spatial analysis was performed using ArcGIS Desktop 10.8, while the reclassified values were categorized using the Natural Breaks method. The results indicate that water-regulating ecosystem services in the Upper Ciliwung Watershed degraded over the ten-year period. The area classified as low increased from 12,493.90 ha (81.94%) in 2015 to 13,630.20 ha (89.39%) in 2025, while the moderate class decreased from 2,644.38 ha to 1,598.94 ha, and the high class declined from 109.17 ha to 18.31 ha. This degradation indicates a decline in the watershed’s capacity to retain and infiltrate rainfall, thereby increasing flood risk in downstream areas. The recommended management measures include revegetation of open areas, implementation of agroforestry practices on agricultural land, stricter spatial planning controls in settlement areas of the Puncak region, and strengthened interjurisdictional coordination based on the one river, one plan approach.]]>
