Characterizing and understanding the changes in the flow regimes of rivers have been challenging. Existing global river network datasets are not updated and can only identify rivers wider than 30 m. We propose a novel automated method to map river networks on a monthly basin scale for the first time at 10-m resolution using Sentinel-1 Synthetic Aperture Radar, Sentinel-2 multispectral images, and the AW3D30 Digital Surface Model. This method achieved an overall accuracy of 95.8%. The total length of the Yellow River network produced is 40,280 km, approximately 3.2 times that of the Global River Widths from Landsat (GRWL) database, more effectively covering small and medium rivers. The monthly river geometry revealed a positive correlation between river network area and precipitation. This study is expected to provide a cost-effective alternative to accurately mapping global river networks and advance our understanding of the changes and drivers of river systems.