Until today hydromorphologically effective restoration measures in the floodplain context have been successfully carried out. The effects of the measures were scientifically investigated in an interdisciplinary manner in order to obtain an overall view of the riverine landscape ecosystem and its functionality.
For several generations, almost all major rivers in Germany have undergone massive changes. These include shortening of the course, the fixation of riverbanks, the control of the flow through groynes as well as interventions in the water balance through dams. The removal of deadwood as part of maintenance work also changed the characteristics of the rivers considerably. However, it is precisely the vital river-floodplain ecosystems, which are linked to the alternation of flooding and low water, that provide a multitude of different habitats and are used by highly specialised animal and plant species. They are hotspots of biological diversity. They also provide unique ecosystem functions that are important for an intact environment.
At present, less than 10% of the river-floodplain ecosystems in Germany have the necessary ecological functionality. There is therefore enormous potential to increase biological diversity in Germany through restoration measures in riverine landscapes in order to improve the provision of ecosystem functions such as species and habitat diversity or water purification.
With the joint research project ‘Wild Mulde’, concrete hydromorphological measures were implemented at the Lower Mulde in Central Germany and their effectiveness on the provision of (selected) ecosystem functions was investigated.
The project aims to enable an interdisciplinary synthesis and visualize the effectiveness of restoration measures. For instance wit the deveolpment of the parameter ‘Hydrological Distance’, which is an indicator for river-floodplain connectivity and plays an important role in explaining the distribution of animal and plant species or the sediment retention in the investigated floodplains.
Furthermore, first morphological effects of the measures are becoming apparent, e.g. in the development of a sediment accumulation in the river in the area of the measure ‘restoration of a natural river bank’. This was recorded by comparative measurements of the river bed topography. This gives positive signals that the progressive river bed erosion can be counteracted by natural banks and is probably due to the fact that material breaking away from the cut-off bank is deposited again along the slip-off slope.
Further, a new gravel bank has been established on the new river wood in UG5 to such an extent that annual pioneer vegetation has already been able to settle here and habitats for e.g. the Little Ringed Plover as a breeding bird have been created.
These initial results show that degraded river-floodplain ecosystems can be successfully restored to dynamic conditions through hydro-morphological restoration measures, thereby counteracting the progress of biodiversity loss.