Hydrology

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Rain near the village Lunde, The north of Funen, Denmark.

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Hydrology is the study of the water cycle. Natural and man-made processes guide water in its varied forms to a variety of ends. Use as irrigation, drinking water and process water by man is very common.

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[edit] Hydrology Lessons

[edit] Diffusion

For a source contaminant concentration \ C_0 entering a flow of velocity \vec U at a distance \ x upstream from a point, the downstream concentration \ C at that point is determined by the ratio...

\frac{C}{C_0} = e^{\frac{x*\vec U}{D}}

Where... \ D is the local dispersion coefficient determined by \ D = 0.067 * depth * V_f

and where friction velocity is V_f = \sqrt{g*depth*ChannelSlope}

[edit] Velocity Distribution in an Open Channel (River)

Velocity distribution within a river follows a standard velocity profile for a confined space (pipe-flow)with the exception that the vertical distribution is truncated at the surface due to reduced friction with atmospheric gases versus the high friction against riverbed materials.

Boundary Layer thickness, also known as the displacement thickness, is defined by:

\delta_d = \int_0^H \frac{1}{H} \left( 1-\frac{\vec u}{\vec U} \right) dz

where \vec U is the average velocity and \vec u(x) is the velocity distribution in a channel of uniform depth \ H.

\bar U = \frac{\int_A \left( \rho \vec V \cdot \hat n \right) dA}{\rho A}

So in the case of this river, where the current is always normal to the cross-sectional area of the river (idealized)...

\bar U = \frac{\int_x \int_y \left( \rho \vec V \right) dydx}{\rho A}

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  • Physical Properties of the Oceans
  1. Wikipedia article:Temperature
  2. Wikipedia article:Density

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Additional helpful readings include:

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