Why Fly across the Tasman River and not build a Bridge?

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We often get asked the question “why do you fly by helicopter acres the Tasman River to start the Alps 2 Ocean Trail, why don’t you build a bridge?”

This seems a fair question until you understand the that the Tasman River is what’s known as a braided river. In New Zealand a braided river is one that flows in multiple, mobile channels across a gravel floodplain. Braided rivers carry high sediment loads and the channels repeatedly branch and rejoin creating an intervening pattern of low islands and shallow bars. The riverbed’s substrate is hard and there is little cover in terms of vegetation, or litter, because of the dynamic character of the habitat.

Because the branches are constantly moving, it makes predicting their location almost impossible.  Bank-to-bank floods are also to be expected about every decade. 

 

Ans this is why it’s so difficult (i.e. expensive) to build a bridge, the river is ever changing and susceptible to flooding. As an example, this is what’s happened to the section of trail build just north of the Jolly Road Car Park, taken on our tour this week. The river has eaten away past the trail into the private land and is still going…

Tasman River A2O Trail Erosion

 

And this is why we fly by helicopter across the Tasman River… :)

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