What is a response?
A response by society or policy makers is the result of an undesired impact and can affect any part of the chain between driving forces and impacts. An example of a response related to driving forces is a policy to change mode of transportation, e.g. from roads (cars) to rails (trains) or water (ships) or the EU Water Blueprint which concentrates on better integration of water policy objectives into other policies (so-called cross-compliance) (EC 2012). Responses related to pressures can be grouped into restoration and mitigation measures. Examples are to restore riparian zones along rivers and lakes through the removal of riprap used for bank protection or to mitigate the migration barrier caused by dams and weirs in rivers with a fish passage.
The information hereafter focuses on responses related to pressures i.e. concrete restoration and mitigation measures. Restoration embraces both so-called full and partial restoration and result in a more natural state of the ecosystem e.g. environmental flow regime, stream re-meandering, dam removal. Partial restoration is also known as rehabilitation. Mitigation measures reduce the impact of the pressure and mostly serve a specific aim, but do not necessarily make the ecosystem more natural e.g. a fish passage besides a dam or weir (see e.g. Freshwater Blog on Mitigating the ecological effects of water storage pressures)
Below a selection of websites is given which holds information on relevant aspects of restoration and mitigation measures. Acknowledging there are numerous websites with information about individual projects, the selection given here are chosen because of the overview or for an important feature.
Database on river restoration projects
As part of the LIFE+ RESTORE project a WIKI on river restoration projects has been created and populated. It is an interactive source of information on river restoration schemes from around Europe. The database can be explored by different categories: country; monitoring or implementation costs, natural flood risk management and many more. It is also possible to add new restoration case studies. Anno September 2017 the database holds information of > 1,000 case studies.
Catalogue of hydromorphological restoration measures for rivers, streams and floodplains
The FP7 REFORM project focused on cost-effective monitoring of hydromorphological modifications of rivers and streams and effective river and stream restoration measures (www.reformrivers.eu). Following a river characterisation and status assessment the need for restoration is identified (Figure 2. The project has prepared 60 factsheets for restoration measures for the following aims:
- Water flow quantity improvement
- Sediment flow quantity improvement
- Flow dynamics improvement
- Longitudinal connectivity improvement
- River bed depth and width variation improvement
- In-channel structure and substrate improvement
- Riparian zone improvement
- Floodplains/off-channel/lateral connectivity habitats improvement
The factsheets are online available at: http://wiki.reformrivers.eu/index.php/Category:Measures
Natural water retention measures
Natural Water Retention Measures (NWRM) are multi-functional measures that aim to protect and manage water resources and address water-related challenges by restoring or maintaining ecosystems as well as natural features and characteristics of water bodies using natural means and processes. Their main focus is to enhance, as well as preserve, the water retention capacity of aquifers, soil, and ecosystems with a view to improving their status. To share experience an online platform has been created holding a catalogue of NWRM, case studies and guidance on implementing NWRM.
Overview of river restoration and dam removal in the United States
Dams have a fundamental impact on a river by blocking the movement of fish and other aquatic species, inundate river habitat, impair water quality, and alter the flow regime of water and sediment necessary to sustain river life. In the US are more than 90,000 dams. Many do no longer serve the purpose for which they were originally built. American Rivers directly contributes to remove dams already > 200 and assists government agencies and non-profits to expand their capacity to restore rivers through trainings and focused program assistance.
For an overview of dam removal please consult the WIKIPEDIA page on Dam Removal.
Natural water retention measures
The general lack of knowledge derived from integrated, well-designed and long-term restoration schemes is striking. A conceptual framework can help to address this problem. Within the EU FP5 project WISER conceptual models according to the DPSIR approach which provide a structured overview of the literature have been developed for three common river restoration measures: riparian buffer management, instream mesohabitat enhancement and the removal of weirs and small dams. The framework highlights recurrent cause–effect chains, that is, commonly observed relationships of restoration measures (response) and their effects on abiotic and biotic conditions (status - impact). Four major questions have been addressed:
- Which organisms show clear recovery after restoration?
- Is there evidence for qualitative linkages between restoration and recovery?
- What is the timescale of recovery?
- What are the reasons, if restoration fails?
Such conceptual models can provide useful new tools for devising more effective river restoration, and for identifying avenues for future research in restoration ecology in general (Feld et al. 2011).