Large rivers have been selected as one of the satellite topics both within WP3 and WP4, because of their particular features which could not be analysed in the case study catchments framework. Large rivers are considered rivers with a catchment larger than 10,000 km² and > 100 m³/s. This encompasses rivers such as the Danube, Rhine, Rhône, Ebro, Vistula but also major tributaries such as the Sava, Narew, and Main rivers. Most fulfil major socio-economic functions, which will remain strongly modified and thus direct the options for rehabilitation. Because of their multifunctional use, large rivers can often only be partially rehabilitated or mitigated to achieve Good Ecological Potential according to the Water Framework Directive. This report addresses both hydrological modifications and restoration (rehabilitation, mitigation) following a DPSIR approach for six case studies that are spread across Europe

The aim of this deliverable is to address the impact of hydromorphological degradation on floodplain and riparian ecosystems, with specific focus on vegetation, fish and invertebrate responses and to provide guidance on how to identify those impacts. 

An introductory chapter summarises the research context and reviews the lessons for managers and stakeholders. Based on the results of the analyses, and the river styles typology developed in Work Package 2 of REFORM, a generic process is recommended for assessing the impact on floodplain and riparian ecosystems, incorporating our key findings. It also highlights the usefulness and limitations of existing EU Directives in providing a suitable legislative framework. 

Assessments of instream impacts on riverine ecosystems make use of multi-site datasets, riparian and floodplain ecosystems are not subject to this type of extensive monitoring; hence, the results presented here are based primarily on case studies from across Europe.

Work Package 3 of REFORM focuses on the impacts of hydromorphological changes on river and floodplain ecosystems. The main research objectives of deliverable 3.3 are:

• To establish empirical relationships between the biota, flow dynamics, substrate complexity/habitat heterogeneity and sediment dynamics.
• To select and develop candidate indicators for WFD quality elements that quantify impacts of hydrological and morphological degradation in rivers.
• To develop novel biological indicators capable of diagnosing hydromorphological stressors in a multiple stressor environment.
• To advise on the design of monitoring programs to detect hydrological and morphological degradation.
• To address the importance to quantify uncertainty in biology based hydromorphological assessment and discuss the implications of uncertainty for monitoring and assessment.
  

The aim of this deliverable is to conceptually model and empirically test the response of biota to the effects of both hydromorphological pressures acting in concert with one another or with other types of pressures. Best use is made of existing large national monitoring datasets (Denmark, UK, Finland, France, Germany, Austria & WISER datasets), case studies and modeling to provide evidence of multiple stressors interacting to alter river biota (Biological Quality Elements: BQE).

The purpose of WP3 is to address degraded river systems. The aim of the first deliverable D3.1 was to begin the development of metrics which indicate the impact of hydromorphological degradation on biota  using existing data. The output, an informed choice of key metrics, aims to support the stakeholder decision making processes and their ability to target desired project goals. These indicators of degradation should be viewed as an interim solution while a more comprehensive and tested approach is produced from WP2 and the final system developed will be an integral part of WP6.