At 820 miles long, the Rhine is a small river compared to the Missouri (2540 miles) and the Mississippi (2348). Rhine barge traffic is vital to inland cities and industries, so the Rhine was manipulated beginning in the 1700s. Flood control shortened the channel and eliminated 85 per cent of alluvial habitat (wide floodplain, backwater and oxbow lakes). Flood hazards increased as the natural course was altered. After catastrophic floods in 1993 and 1995, modern management plans were developed.
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The Rhine arises in Switzerland and flows north through Germany and France into the Netherlands. The High Rhine in Switzerland, with extensive habitat for fish and migratory birds, is targeted for hydroelectric development. The Upper Rhine is 250 miles long, extending from Basle, Switzerland, to Bingen, near the Rhine's confluence with the Main. Flood control began around 1860 for navigation. Eight hydroelectric dams and two reservoirs have been built since 1930. The Middle Rhine above Koln (Cologne) is 100 miles long and includes unique alluvial forests. The Lower Rhine, downstream from Koln, is densely populated and highly industrialised. Major flood control works began around 1900.
Channelling the Rhine
Older methods of flood control were focused on commercial traffic and involved changing the river channel and narrowing the flood plain. Dykes built along the river channel separated the Rhine from the alluvial habitats where annual flooding renewed the water table and supported wildlife. The shipping lane was dredged to a uniform depth and width. Fluctuating sand and gravel banks were replaced with walled concrete embankments. Oxbows and backwaters (older channel remnants) were cut off. Floodwaters had nowhere to go except downstream.
The 1990s rain-on-snow floods did not match the record flood of winter 1784 that developed behind an ice jam. In 1993, 50,000 residents in Koln and tens of thousand in France and the Netherlands were evacuated. Citizens complained that dykes, concrete embankments and channelling caused the flooding. In the winter of 1995, floods stopped river traffic, and 200,000 people evacuated. The Rhine is the world's most trafficked inland waterway, so the barge industry alone lost millions of dollars daily. The Netherlands' property losses reached £0.6 billion.
In 1995, the International Commission for the Protection of the Rhine (ICPR) formed a committee to draft an "Action Plan on Flood Defense" for the Rhine watershed. Participants were from France, Germany, Belgium, Luxembourg and the Netherlands. Their plan, the Interregional Rhine/Meuse Activities (IRMA), forced flood prevention measures between 1997 and 2001. Their immediate action plan included: increasing awareness by publishing risk maps of the flood plain, reducing flood stages downstream from dams and improving forecasting.
Room for Rhine
Long-term flood control improvements focus on widening the flood plain to make room for floods before they reach densely populated areas. The Room for Rhine approach will also widen (but not fully restore) wetlands and wildlife habitat. This includes removing any "groynes" (concrete embankments) along the river, excavating (lowering) parts of the flood plain that are seldom flooded, opening old channel remnants such as backwaters and oxbow lakes and removing levees built on the flood plain.
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