3.3 Physical characteristics of natural waters
A river's physical characteristics include:
speed of flow/turbulence
the presence of plants and macroscopic animal life.
The physical characteristics are determined by location, geology and climate of the catchment area. In turn they influence the chemical and biological characteristics of the watercourse.
The physical appearance may give you initial clues to the condition of the river. Figure 12 shows how the aquatic ecosystem is a complex set of physical, chemical and biological interrelationships. Nutrients and dissolved oxygen may be essential to aquatic life but other conditions must also be satisfactory.