An approach for determining low flow thresholds in streams based on fluvial processes.

摘要

Withdrawal of water from streams stands to have a wide range of effects on the geomorphic function of those streams, with possible consequences for sediment transport, channel form, stream habitat, and human use of the system. This research involved the development of flow thresholds for water withdrawal based on sediment transport characteristics for a sample fluvial system, Brandy Creek. Field data on the form and function of Brandy Creek were combined with modeled streamflows in order to describe the amount of flow energy available in the Brandy Creek fluvial system as compared to the flow energy required for sediment movement on the stream bed. Several expressions of stream energy were explored; it was concluded that flow thresholds produced based on Komar's critical velocity for sediment movement were more representative of in-stream conditions. The velocity-based thresholds were applied to storm hydrograph data in order to generate a series of flow thresholds and accompanying permissible rates of water withdrawal. This work represents a "first step" in a potentially large-scale, long-term investigation into the implications of water abstraction on river and stream systems.