![]() This article aims to highlight the singularity of a specific type of non-perennial rivers where aquatic conditions are anomalous, which we denominated ‘Dry Rivers’ (hereafter, DRs). This is especially critical when rivers rarely experience wet conditions regimes but are included in the same category of those able to harbor an aquatic environment for some time. Particularly, the use of the term ‘ephemeral’ is not always clear, as we can find descriptions with very different hydrological regimes (see Table 1). Yet, such distinction in the literature is not adequately addressed on occasions. For example, some authors have coined the term ‘IRES’-intermittent rivers and ephemeral streams (sensu ) to, in practice, distinguish between fluvial ecosystems exhibiting short and large dry phases, respectively. The arbitrariness in the use of these diverse terminologies likely results in misleading knowledge about the ecology of specific types of non-perennial rivers. However, the fact that standard and robust criteria to properly classify the different proposed typologies are lacking makes the existing ones operationally weak. Hydrologists, ecologists and geomorphologists have generated a vast terminology in an attempt to classify the huge universe of non-perennial rivers into different types, according mainly to the hydrology and, in particular, to dry phase duration (see Table 1). With this paper, we ultimately expect to put value in Dry Rivers as non-perennial rivers with their own ecological identity with significant roles in the landscape, biodiversity and nutrient cycles, and society thus worthy to be considered, especially in the face of exacerbated hydrological drying in many rivers across the world. Finally, we drew main conclusions where major knowledge gaps and research needs are also outlined. We applied an integrative approach that incorporates to the limnological perspective the terrestrial view, useful to gain a better understanding of Dry Rivers. ![]() ![]() We explored the capacity of Dry Rivers to provide ecosystem services and described main aspects of anthropogenic threats, management challenges and the conservation of these ecosystems. Secondly, we analyzed existing knowledge on distribution, geophysical and hydrological features, biota and biogeochemical attributes that characterize Dry Rivers. ![]() We firstly reviewed the variety of definitions used to refer to these non-perennial rivers featured by a predominant dry phase with the aim of contextualizing Dry Rivers. This paper aims to show that Dry Rivers are ecosystems in their own right given their distinct structural and functional characteristics compared to other non-perennial rivers due to prevalence of terrestrial conditions. Conceptually, Dry Rivers would represent the extreme of the hydrological continuum of increased flow interruption that typically characterizes the non-perennial rivers, thus being preceded by intermittent and ephemeral rivers that usually support longer wet phases, respectively. We define Dry Rivers as those whose usual habitat in space and time are dry channels where surface water may interrupt dry conditions for hours or a few days, primarily after heavy rainfall events that are variable in time and that usually lead to flash floods, disconnected from groundwater and thereby unable to harbor aquatic life. ![]()
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