| 10 Aug 2026
Stream connectivity and governing processes in high-mountain wetlands
Abstract. High-mountain wetlands (hereafter wetlands) have the potential to store and release large volumes of water. They provide substantial contributions to water supply for highland communities and receiving lowlands and their extended residence times can buffer water demand during drier periods. Despite their hydrological significance, major gaps remain in understanding the connection between wetlands and streams, which prevents us from accurately conceptualising them in models. We used a combination of conservative fluorescent tracing and monitoring of rainfall-runoff and wetland water levels to develop a perceptual model of connectivity between wetlands and streams. The experiments were conducted during the wet or dry season in five study catchments (0.38 km2 – 12.58 km2) from northern Ecuador to southern Peru. Fluorescein was introduced into wetlands and monitored downstream with activated carbon samplers for 5–12 months. Our results suggest travel times from less than 1 week to upwards of 3 ½ months, with one experiment seeing little to no response. Results indicate that wetlands have a stronger hydrological connection to streams in the wet season than in the dry season, where in some cases we observed no connection at all. Multiple peaks in fluorescein concentration from a single injection during the wet season may suggest that the wetlands contribute to streamflow via multiple pathways and processes. The results demonstrate a complex connection between wetlands and streams, controlled by topographic configuration and season, amongst other factors. However, persistent contributions from wetlands to streams observed several months after dye introduction support their significance to downstream, year-round water supply. The results provide improved understanding of wetland-stream connectivity that informs the development of models to address the need for site-specific evidence of wetlands’ influence on water supply and the ability to scale this information in space and time.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Hydrology and Earth System Sciences.
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