CORE UNIT: PATTERNS AND PROCESSES IN THE PHYSICAL ENVIRONMENT River 1 80 81 82 83 84
H
River 2
Drainage basin
Fig. 3 Watershed and drainage basin
River 3 Fig. 4 Draw a line along the watershed on this map.
As the river moves along its course it tries to reach a balance between erosion and deposition. This balance creates a graded profile. Because of the varied rock types over which rivers flow, they rarely achieve a graded profile so the slope of a river’s course is instead called its long profile.
Source
Long profile Height Sea Graded profile
Youthful (upper) course
Mature (middle) course
Fig. 5 Long and graded profiles of a river Drainage patterns
Drainage patterns are the shapes made by a river and its tributaries as they flow over the landscape. There are three main patterns visible in the Irish landscape.