How the water reacts with the land
As opposed to Hydrodynamics - how the water reacts in a rapid. Hydrotopography looks at how the land can become a feature in white water We will look at how the land can negatively and positively affect a rapid, and how different river beds lend them selves to different features.
As water enters a rapid fluid dynamics kicks in, we know there are five layers - surface flow, laminar flow, helicoidal flow, laminar flow and bottom flow. Since the layers are reacting to the uneven bottom of the river they get pushed up in to the air in the form waves. If there is a sudden drop in the the river bottom a hole can form. These features are constant and they are the core backing to what is white water
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Hydrotopography
Eddy
An eddy is created with the river is blocked by an obstacle. As water passes by the obstacle it realizes that there is an empty space that needs to be filled. Since water needs to be flat and because of gravity the water is drawn back upstream (the same as a hole). An eddy can provide a spot to re group and catch ones breath after or mid rapid.
Obstacle
The object blocking the current. This is usually a rock however it could be human made, a tree, a boat, or an animal. A hole also creates an eddy in or behind its back wash Eddy line
The eddy line, is a line of confused water separating the down stream current of the river, and the up stream current of the eddy. Because this current is unsure where it is going, it goes in all directions - upstream, downstream, down to the bottom of the river and back up again. In most circumstances we want to be either in the eddy or in the current. Not on the Eddy line. |
Sieve, Strainer
A sieve or strainer is a group of objects or an object that allows water through, but nothing larger. I like to imagine a pasta strainer - water goes through, pasta does not. You are the pasta.
Some examples include: rocks piled together, trees, shopping carts, cars. really anything that allows water through but NOT you. |