Three different methods to analyse fine sediment deposits on a gravel using pictures were presented in this paper. First, a manual digitization and a automated procedure were achieved on aerial pictures in 2006; Another automated procedure was performed on pictures shot in 2010 from the side bank of the river at 15m above the gravel bar approximately. These methods were applied to estimate the surface of fine sediment deposits before and after a flushing event. They yield similar results even if the first automated procedure used for the aerial pictures was able to capture smaller patches of fine sediments. The total surface of fine sediment deposits seems to be similar before and after a flushing event, but the distribution is quite different. Before a flushing event, a significant amount of fine sediment deposits are mixed with coarser sediments. After the flushing event, one can observe more large fine sediment deposits located on the downstream part of the secondary channel and at the channel margin. Most of the small fine sediment deposit patches were washed out. Several questions remains on the dynamics of these deposits during the flushing event, during a natural flood and between events.