PNNL

Abstract

Transitions between dry and wet states are the defining characteristic of non-perennial rivers and streams, which constitute the majority of the global river network. Although past work has focused on stream drying characteristics, there has been less focus on how hydrology, ecology, and biogeochemistry respond and interact during stream wetting. Wetting mechanisms are highly variable and can range from dramatic floods and debris flows to gradual saturation by upwelling of groundwater. This variation in wetting affects important ecological and biogeochemical functions, including nutrient processing, sediment transport, and the assembly of biotic communities. Here, we synthesize evidence describing the hydrological processes underpinning different types of wetting, associated biogeochemical and organismal responses, and the potential scientific and management implications for downstream ecosystems. This combined multi-disciplinary understanding of wetting dynamics in non-perennial streams will be key to predicting and managing for the effects of climate change on non-perennial ecosystems at large scales.