Characteristics of River Flow

As previously mentioned, lotic systems (rivers and streams) are characterized by continuously flowing waters. These flows are the vitality of the systems and are very dynamic, showing variation on several time scales. Although the traditional focus has been on downstream flow, the lateral movement of water and other materials in a river is also very important (as we shall examine in more detail in the section on floods). Water movement is critical to the distribution of vital nutrients, gases, and small organisms (such as zooplankton). The movements of water and sediments in the river channel are called fluvial processes.