Work Package 2 of REFORM focuses on hydromorphological and ecological processes and interactions within river systems with a particular emphasis on naturally functioning systems. It provides a context for research on the impacts of hydromorphological changes in Work Package 3 and for assessments of the effects of river restoration in Work Package 4. 

Deliverable 2.1 of Work Package 2 proposes a hierarchical framework to support river managers in exploring the causes of hydromorphological management problems and devising sustainable solutions. The deliverable has four parts. Part 1 (this volume) provides a full description of the hierarchical framework and describes ways in which each element of it can be applied to European rivers and their catchments. Part 2 includes thematic annexes which provide more detailed information on some specific aspects of the framework described in Part 1. Part 3 includes catchment case studies which present the application of the entire framework described in Part 1 to a set of European catchments located in different biogeographical zones. Part 4 includes catchment case studies which present a partial application of the framework described in Part 1 to a further set of European catchments.

In assessing hydromorphology, to date there has been too strong a reliance on the reach scale, on the river channel and its current condition, and on focusing on specific river reaches in order to assess rivers, diagnose river problems and design intervention, rehabilitation and restoration measures.

The research objective for Deliverable 2.1 is to develop a process-based, multi-scale, hierarchical framework to support river managers in assessing the hydromorphological character of rivers, exploring the causes of hydromorphological problems, and devising sustainable management solutions.

The rationale for developing the framework lies in the fact that the hydromorphological character of river reaches depends not only upon interventions and processes within the reach but also within the upstream and sometimes the downstream catchment. In addition, the character of river reaches often responds in a delayed way to processes and interventions within the catchment. As a result, understanding hydromorphology at the reach scale requires understanding of both current and past processes and interventions not only within the reach but also at larger spatial scales.

Founded on frameworks proposed in the scientific literature, the REFORM framework is open-ended and user-oriented, allowing users to incorporate any suitable information and tools that may be locally available, but at the same time indicating the minimum level of information required across time and space scales, and some of the simple tools and Pan-European data sets that are available to provide this information when suitable local or national data sets and tools are not available.

For sustainable solutions to river management problems, it is crucial to develop understanding of the functioning of the reach in the context of the character and changes in the spatial units (segment, landscape unit, catchment, biogeographical region) within which the reach is located. It is also crucial to understand that the character of reaches depends heavily on the nature of the riparian zone and, where present, the floodplain, and also the degree to which the river is able to interact with its riparian zone and floodplain. By incorporating information of these types, the present and past character of the reach can be interpreted in the context of present and past changes that have occurred at the reach and all larger spatial scales, and that have cascaded down from the catchment to influence the reach. It also allows interpretation of how changes in the floodplain and riparian zone interact with changes within the river channel. The ways in which reaches of different type within a catchment have responded to changes / interventions in the past provides crucial information for forecasting how reaches may change in the future, whether the catchment continues to be used and to function as at present or to be subjected to different scenarios of change.  The REFORM framework allows users to incorporate all of these multi-scale spatial and temporal aspects into river assessment and management.