Non-perennial segments in river networks
Citation:
Datry, T., A. Boulton, K. Fritz, R. Stubbington, N. Cid, J. Crabot, AND K. Tockner. Non-perennial segments in river networks. Nature Reviews Earth & Environment. Nature Portfolio, Berlin, Germany, 4:815–830, (2023). https://doi.org/10.1038/s43017-023-00495-w
Impact/Purpose:
In this review, we explore key insights from research on NPRs in the context of network-scale riverine connectivity. We focus on aquatic ecosystem responses to drying from reach to river network scale. We then explore the implications of excluding non-perennial river segments from policy and management. Our central message is that the conceptualization of rivers as arrays of co-occurring perennial and NPRs must be matched with changes to river management that recognize the importance of integrating NPRs into strategies and actions that support network-scale biodiversity, ecological processes and ecosystem services.
Description:
Non-perennial river segments — those that recurrently cease to flow or frequently dry — occur in all river networks and are globally more abundant than perennial (always flowing) segments. However, research and management have historically focused on perennial river segments. In this Review, we outline how non-perennial segments are integral parts of river networks. Repeated cycles of flowing, non-flowing and dry phases in non-perennial segments influence biodiversity and ecosystem dynamics at different spatial scales, from individual segments to entire river networks. Varying configurations of perennial and non-perennial segments govern physical, chemical and ecological responses to changes in the flow regimes of each river network, especially in response to human activities. The extent of non-perennial segments in river networks has increased owing to warming, changing hydrological patterns and human activities, and this increase is predicted to continue. Moreover, the dry phases of flow regimes are expected to be longer, drier and more frequent, albeit with high regional variability. These changes will likely impact biodiversity, potentially tipping some ecosystems to compromised stable states. Effective river-network management must recognize ecosystem services (such as flood risk management and groundwater recharge) provided by non-perennial segments and ensure their legislative and regulatory protection, which is often lacking.
