Assessing the Hydrogeomorphic Effects of Environmental Flows using Hydrodynamic Modeling

Area of Science:

• Environmental science
• Hydrology
• Riverine ecology

Background:

• Environmental flows (e-flows) are crucial for managing river systems impacted by impoundments.
• Process-based approaches are vital for modified rivers with over-allocated water resources.
• Hydrodynamic models (1D and 2D) can simulate hydrogeomorphic processes for e-flow development.

Purpose of the Study:

• To demonstrate the utility of hydrodynamic models in targeting and assessing environmental flows.
• To support stakeholder decision-making within a collaborative e-flow framework.
• To evaluate the effectiveness of 1D and 2D models in an e-flow experiment.

Main Methods:

• Utilized one-dimensional (1D) and two-dimensional (2D) hydrodynamic modeling.
• Applied modeling to an environmental flow experiment on the Rio Chama, New Mexico.
• Focused on improving brown trout spawning habitat by flushing fine sediments.

Main Results:

• The 2D hydrodynamic model provided significantly more insight into hydrodynamic and sediment transport processes.
• The enhanced understanding from the 2D model led to a reduction in the recommended e-flow discharge.
• Effective e-flow assessment was achieved even with limited calibration/validation data.

Conclusions:

• Two-dimensional hydrodynamic models are valuable tools for enhancing process understanding in environmental flow management.
• These models aid in developing precise e-flow recommendations and support adaptive management strategies.
• Hydrodynamic modeling can be successfully applied even in data-scarce environments for effective river management.