Rules of Engagement: 2

Although the hierarchical assessment framework for hydromorphology stresses the use of readily available data sets, there is no substitute for field survey by a geomorphologist, at least at the reach scale, to verify information extracted from secondary sources; to record features and other information that cannot easily be identified from secondary sources; and to interpret forms and processes directly in the field. Therefore, if pre-existing field surveys are absent or limited, new field surveys should be implemented as widely as possible by an expert in order to ensure the robustness of inferences drawn from secondary information.