How do you classify the different biological zones in Rivers and streams lengthwise?

The concept of classifying the river and streams is known as the river continuum concept which classifies the river into the sections after the occurrence of living organisms. Rivers can be classified as into three rough classifications namely : headwaters, mid-reaches and lower reaches.

For classification of river into the biological zones, it is classified into five zones. These zones are Periphyton, Vascular Hydrophytes, then periphyton again, then Phytoplanktons and the last is the Zooplankton.