River Morphology

The science of geomorphology studies the forces that shape the earth's surface at the present time. The word is formed from Greek words: geo (earth) morph (form or shape) and logos (study or knowledge). Present day structures are studied not only to help us understand the geological features we see today and the forces that created them, but also to help us understand the features from previous ages that we see recorded in geological history.

There are several geological agents which work to shape the face of the earth: volcanos, wind, ice, and water. As a river group we are of course interested in water. Even more specifically, we are interested in the geological work done by water as it flows in a stream channel.

Water, when rain deposits it on an upland, possesses energy. It possesses potential energy, or the energy of position. As the water begins to flow down hill, this potential energy is converted into kinetic energy, or the energy of motion. This kinetic energy can be used up in various ways. For example, turbulence and friction within the moving water uses up kinetic energy. In addition, kinetic energy is used when the water erodes away the surface of the stream channel it is passing through or moves sediments along the stream bed. By the time the river ends in a standing body of water, for example when it enters a lake, all of this kinetic energy has been converted into thermal energy, or heat energy. This heat energy, uniformly spread through the environment, is the most degraded form of energy and cannot accomplish anything.

Potential Energy -> Kinetic Energy -> Heat Energy

As this kinetic energy of the moving water is transformed into heat energy it performs work, i.e. the application of force over distance. It is this physical work that moves the water and forms the river into what we see.

Geomorphologists have begun to understand that the natural configuration or shape that a river gradually evolves is the one that most efficiently performs the total work (the movement of water and sediments) of the river. We will look at this idea more closely.

River morphology is a complex subject. We subdivided it into the areas below, but you should remember that these are often related to each other. You can visit the pages in the sequence below to get a fairly logical development of the topic, or you can start with whatever area interests you and link into other areas to get any background information you need.

 


 
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