This document provides guidance on characterizing the modifications of river hydromorphological features described in EN 14614:2020. Both standards focus more on morphology than on hydrology and continuity, and include a consideration of sediment and vegetation. This document will enable consistent comparisons of hydromorphological forms and processes between rivers within a country and between different countries in Europe, providing guidance for broad-based characterization across a wide spectrum of hydromorphological modification of river channels, banks, riparian zones and floodplains. Although of lesser focus, it considers the indirect effects of catchment-wide modifications to these river and floodplain environments. Its primary aim is to assess departure from naturalness as a result of historical and modern human pressures on river hydromorphology, and it suggests suitable sources of information (see EN 14614:2020, Table A.1) which may contribute to characterizing the modification of hydromorphological properties. In doing so, it does not replace methods that have been developed for local assessment and reporting. Decisions on river management for individual reaches or catchments require expert local knowledge and vary according to river type.