In 1812, Tulla went to the governments of the riparian nations and sought approval for his plan: He was going to "rectify" the river, controlling its flood waters and making them predictable; lowering the local water table so that the bogs and wetlands would dry up and become arable farmland, eliminating islands and secondary channels that stood in the way of the "efficiency" of the river's flow, making the Rhine "more perfect": ie, straight. He secured agreement from most of the riparian nations, but he was unable to get a clear go-ahead from the French, who were caught up in Napolean's disasterous invasion of Russia at the time. (Points to people who can say what was happening in the US during this same time, or say the interesting strategy the Russians used to foil the French that winter!) The project stalled for several years until finally Napolean's government dissolved and control was returned to local chiefs on the French bank and permission was granted to begin work.

To begin, Tulla blasted the meandering river, cutting through the meanders and oxbow lakes and steepening the grade of the channel. He shortened the river by 82km. He made the bed particular dimensions in different sections to control the downcutting rate. Unfortunately, the correct equation for calculating the effect of cross-sectional area and perimeter on the velocity of the river and thus downcutting rate had not been determined at this time (it was found at the end of the century by Robert Manning and named the Manning Equation). This equation also had a cube-root in it, which... without the help of a calculator... was a very difficult and time-consuming calculation to make!

In 1827 Johann Gottfried Tulla died in Paris, though his work continued into the late 1800s. His gravestone read, "“Dem Bändiger des wilden Rheins”, or "the Tamer of the Wild Rhine".

Unfortunately, a river is not so simple a beast. The men hadn't cut out the meanders completely, there was still a wiggle in the river's path. The river exploited these curves and began eroding them, forming new meanders and undermining the fortifications on its banks. It also cut down into its bed, just as Tulla had planned, but instead of cutting 1 or 2 meters it cut in some places up to 7. At Isteiner Klotz the river cut down until it hit bedrock, after which it formed a series of impassable rapids. Even today an expensive series of locks is required to traverse this part of the river. Because of the downcutting, the water table fell, taking with it the fertility that the surrounding farmland had enjoyed until then. Now all of this land had to be irrigated with long channels coming out from the river. Sediment eroded from upstream began to deposit downstream, clogging channels and forming new islands and sandbars in places they had never been before.

whoa. . .
» raisedOnSunday on 2007-04-30 11:46:06

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