Riverbeds are often composed of different scales of dunes, whose sizes and shapes are highly variable over time and space. Characterization of these dunes is important in many research studies focused on fluvial processes. A tool is presented here that aims to identify different scales of dunes from riverbed elevation maps. A first step is to separate two scales of bedforms without smoothing steep slopes of the larger dunes. In a second step, dunes are identified and properties are computed.