In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.

The boundaries between perennial , intermittent , and ephemeral channels are not defined , and subject to a variety of identification methods adopted by local governments , academics , and others with a need to classify stream-flow permanence .
The differences between perennial , intermittent , and ephemeral streams are not exact and can change if different measures are used by different groups .