How is the term "ephemeral" best defined?

The term "ephemeral" is best defined as having a brief duration or being short-lived. In the context of environmental science and hydrology, ephemeral streams are those that do not have continuous flow throughout the year; instead, they may only flow for a short period following rain events or during specific seasons. This brief existence is characteristic of ephemeral features, distinguishing them from more permanent or consistent geographical features, such as perennial rivers or established landmarks. Understanding the nature of ephemeral systems is crucial for effective erosion, sediment, and stormwater management, particularly in assessing water quality and aquatic habitats.