The term “restoration” was used for a wide variety of project objectives when river restoration started in Europe in the 1980ies, ranging from landscape gardening (improving the aesthetic value) and river training using bio-engineering approaches to restoring historical conditions (e.g. re-meandering river, left photo) or natural processes (e.g. adding wood to initiate natural channel dynamics, right photo).

Restoration Engineering Approach Restoration Processes Large Wood

According to the European Water Framework Directive, European rivers should achieve “good ecological status”, which only slightly deviates from undisturbed reference conditions, i.e. the objective of restoration must be to develop rivers towards their natural state. A rather new and challenging restoration measures, which has been selected in many River Basin Management Plans, is to “initiate natural channel dynamics” with the objective to restore natural processes and in turn a natural channel pattern and channel features (e.g. pools, riffles, undercut banks).

However, most restoration projects are still restricted to short river reaches several hundred meters in length, and there is very limited knowledge which ecological benefits can be achieved by restoring natural processes at the reach scale given the remaining anthropogenic changes and pressures at larger scales (e.g. altered discharge and sediment supply, water quality problems, nutrient and fine sediment input, missing source populations, river fragmentation, climate change).