Author(s): Nolan Raphelt; Kevin Mayes; Thomas Hardy
Linked Author(s): Thomas Hardy
Keywords: No Keywords
Abstract: The evolution of instream flow assessments over the last five decades from a single minimum flow to defining ecological flow regimes represents significant shifts in the technical and philosophical basis of protecting aquatic ecosystems. The Texas Instream Flow Program has embraced this paradigm shift and integrates subsistence flows, base flows, pulse and overbank flows that address flow and water level requirements for aquatic biota, such as freshwater unionid mussels, fish, and riparian systems. These recommendations specifically incorporate inter-and intra-annual flow variability based on multi-disciplinary assessments. In this study, we explore several instream flow regime scenarios and their implications in terms of sediment transport dynamics to maintain the channel structure based on two hydrologic time periods. The first hydrologic period represents minimal flow alteration while the second period reflects substantial flow alteration. Flow regimes based only on studied ecological components varied in their sediment transport dynamics and generally were not sufficient to produce volumes of water necessary to maintain the underlying physical habitat characteristics of the river. Study results are utilized to recommend a geomorphic flow regime component necessary to maintain dynamic channel equilibrium and therefore the associated physical habitats as part of the overall ecological flow regime.
Year: 2018