The fluvial ecosystems of mountainous areas are considered key areas in relation to the effects of global change due to their climatic vulnerability and relative isolation from the terrestrial environment.

The headwaters, which are mainly found in the upper parts of the valleys of mountain systems, are very important areas from an ecological and biological point of view, as they provide habitats for a great variety of species and are essential for species living in other areas of the river network. The natural temperature regime of river ecosystems is being altered by global change and specifically, changes in water temperature are of particular relevance to ectotherm organisms. Despite evidence of the sensitivity of river ecosystems to global change, changes in the thermal regime are expected to occur more slowly in certain areas of the river network, such as thermal refugia located in the headwaters. However, one of the main problems or challenges in identifying potential thermal refuges is their identification at the river network level.