Stream Gradient

A stream is any flow of water, and water flows from higher elevation to lower elevation on the earth's surface. As it makes its way across the land surface back to the ocean, it may considerably alter the surface over which it flows. RUNNING WATER, a stream, is one of the AGENTS of erosion. The processes associated with running water are referred to as FLUVIAL. In previous activities, we looked at stream systems and their drainage basins, divides, and the tributaries. We examined the relationship between discharge, velocity, and depth.

Another relationship to consider is that of gradient. Gradient is the slope of the stream and is measured by the difference in elevation between two points on a stream divided by the distance between the two points that the water actually flows. Gradient is usually expressed in feet per mile of meters per kilometer. The phrase RISE OVER THE RUN is the "shorthand" of the formula. See the illustration below. Gradient looks at how far the water drops over the distance the water actually flows. The gradient influences the velocity of the stream. The steeper the gradient, the higher will be the velocity if all other factors are held constant.


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