PROJECT DESCRIPTION
BACKGROUND
The delta where the young Rhine coming down from the Alps flows into Lake Constance is a focal point in more ways than one. At the end of the 1950s the delta was hemmed in by dykes and the course of the Rhine moved. This allowed the delta to be systematically drained and given over to intensified agriculture. The waters of the lake, which used to wash over the shores regularly, now no longer flooded large parts of the former delta. The area was also a focal point for meadow-breeding birds on account of its mud flats, shallow waters and humid meadows, as well as being a resting, foraging and moulting site of European importance for migrating birds because of its central location. However, the corncrakes and similar choosy birds, faced with a decline in the ecological value of their real estate, became ever less frequent visitors. Many species are now close to disappearing from the Rhine delta. The vegetation is changing, the peat soil is degenerating and to cap it, the area is increasingly becoming a focal point for another force: tourism, which has planted bathing facilities, camping grounds, restaurants ..... all along the lakeshore. Through this LIFE project, the ecological improvement of the site would be sought in consensus with all interested parties.
OBJECTIVES
A management plan which was already elaborated in 1995 would now be systematically implemented. The LIFE project would concentrate on a 250 hectare humid meadow area behind the dykes, where the hydrological regime would be improved by a semi-natural regulation of water flow. The drainage systems of the project area (an existing nature reserve) and the adjoining agricultural land would be separated from each other so that they could be dealt with in isolation. The objective was to raise water levels in the project area without side effects on neighbouring land users, inhabitants or lakeside camping grounds. This would stop and perhaps even reverse current negative trends in site flora and fauna. To channel tourism, an information centre dubbed 'Rheindeltahaus' would be built parallel to LIFE. Two rangers would be on hand to inform visitors and leisure seekers about nature in general and LIFE in particular.
RESULTS
The site is a 250 hectare meadow area, part of the 2000 hectare Rheindelta nature reserve located where the river Rhine flows into the Bodensee (Lake Constance). Large areas of the Rheindelta were drained in the past to convert these into intensive arable land. Hence, the objective of the LIFE-Nature application was to raise water levels in the project part of the drained delta and to re-establish the traditional litter meadow (“Streuwiesen”) mowing management. However, the ecological and hydrological surveys and assessments of the plan, preparatory to drawing up detailed technical blueprints, revealed two major unexpected obstacles to restoration. In the first place, because of the drainage in the past, the peaty soil had been mineralized, which resulted in land subsidence (Moorsackungen). This was confirmed by a test run in which a ditch was dammed - the outcome was radically different from what had been expected. Second, whereas in the past alkaline water from the Bodensee flooded the delta, now only eutrophic water from the hinterland was flowing into the area. Raising water levels without any additional measures would increase the impact of this eutrophic water. The studies concluded that an improved conservation status of the project area could only be reached through very large-scale technical measures (a long dyke to protect the hinterland, controllable weirs, a pumping system), which were beyond the reach of the LIFE-Nature project budget. Consequently, the Commission and beneficiary agreed in early 2001 to stop the further implementation of the foreseen project measures. The Rheindeltahaus visitor centre, funded from other sources parallel to the LIFE project, was built in 1999. The site is a 250 hectare meadow area, part of the 2000 hectare Rheindelta nature reserve located where the river Rhine flows into the Bodensee (Lake Constance). Large areas of the Rheindelta were drained in the past to convert these into intensive arable land. Hence, the objective of the LIFE-Nature application was to raise water levels in the project part of the drained delta and to re-establish the traditional litter meadow (“Streuwiesen”) mowing management. However, the ecological and hydrological surveys and assessments of the plan, preparatory to drawing up detailed technical blueprints, revealed two major unexpected obstacles to restoration. In the first place, because of the drainage in the past, the peaty soil had been mineralized, which resulted in land subsidence (Moorsackungen). This was confirmed by a test run in which a ditch was dammed - the outcome was radically different from what had been expected. Second, whereas in the past alkaline water from the Bodensee flooded the delta, now only eutrophic water from the hinterland was flowing into the area. Raising water levels without any additional measures would increase the impact of this eutrophic water. The studies concluded that an improved conservation status of the project area could only be reached through very large-scale technical measures (a long dyke to protect the hinterland, controllable weirs, a pumping system), which were beyond the reach of the LIFE-Nature project budget. Consequently, the Commission and beneficiary agreed in early 2001 to stop the further implementation of the foreseen project measures. The Rheindeltahaus visitor centre, funded from other sources parallel to the LIFE project, was built in 1999.