Gradient

A long profile is a side view along the length of a river. It shows how the river’s height and gradient change from source to mouth. Gradient means steepness: a large fall in height over a short distance gives a steep gradient.

The River Tees, in north-east England, provides a named example. It begins at Cross Fell in the Pennines, 754 m above sea level, and flows through upland and lowland landscapes to the North Sea at Teesmouth. Its upper, middle and lower courses show how channel shape, valley profile, gradient, flow and sediment are connected.

A long profile follows the river downstream and shows how its height and gradient change. A cross-profile cuts across it: a channel cross-profile shows the river’s width and depth, while a valley cross-profile includes the valley floor and surrounding slopes.

The gradient describes how steep a slope is. Where contours are close together, the land changes height over a short horizontal distance: the slope is steep. Where the same contour interval is spread over a greater horizontal distance, the slope is gentler.