American Society of Civil Engineers

Modeling Unsteady Flow Characteristics of Hydropeaking Operations and Their Implications on Fish Habitat

by Yi Shen, M.ASCE, (Hydrologist, Texas Parks and Wildlife Dept., Austin, TX 78744. E-mail: and Panayiotis Diplas, (corresponding author), M.ASCE, (Professor and Director, Baker Environmental Hydraulics Laboratory, Dept. of Civil and Environmental Engineering, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 2406 E-mail:

Journal of Hydraulic Engineering, Vol. 136, No. 12, December 2010, pp. 1053-1066, (doi:

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Document type: Journal Paper
Special Issue: Special Issue on River Flow Hydrodynamics: Physical and Ecological Aspects
Abstract: Reservoir releases associated with energy production and flood mitigation need to be reconciled with efforts to maintain healthy ecosystems in regulated rivers. Unsteady flow phenomena caused by hydropeaking operations typically affect riverbed erosion and fish displacement. A three-dimensional hydrodynamic model is used to simulate the flow characteristics during the passage of the rising limb of an observed hydropeaking event in a gravel-bed reach of Smith River, Virginia. The calculated time-dependent water surface elevations, velocities, and shear stresses are compared with field measurements. Further, comparison based on numerical simulations of this historical and a hypothetical "staggering" hydropeaking event reveals that the latter has the capability of reducing the area subject to erosion and prolonging refugia availability for juvenile brown trout. Issues related to the adoption of either a truly dynamic modeling approach or a quasi-steady methodology for simulating unsteady flows are examined through a proposed unsteadiness flow parameter. The insights obtained from this study can assist in properly accounting for the impact of hydropeaking operations on fish habitat and instream flow management.

ASCE Subject Headings:
Rivers and streams
Numerical models
Unsteady flow
Fish management

Author Keywords:
Numerical modeling
Unsteady flow
River mechanics
Stream restoration