Event Title

Longitudinal thermal and solute dynamics in regulated rivers

Presenter Information

Muhammad Rezaul Haider
Bethany Neilson

Location

Logan Country Club

Streaming Media

Start Date

3-28-2017 2:35 PM

End Date

3-28-2017 2:40 PM

Description

Dam releases increase river stage and reverse typical groundwater hydraulic gradients towards the river, which reestablish with the decline of river stage. As the flood, thermal, and solute waves travel downstream in a regulated river, the rate of change in amplitude will be affected both by surface water processes and groundwater exchanges. A dynamic instream water quality model was used to simulate the dynamics of flood, thermal, and solute waves transport through a 90 km portion of a regulated river. A series of flood, thermal, and solute waves of arbitrary magnitudes were released at the upstream boundary. Assuming a homogeneous and unconfined aquifer adjacent to the river, an analytical solution for the aquifer head response to periodic stream stage fluctuations was integrated into the surface water model to estimate the spatially and temporally variable groundwater exchanges and their impact on instream responses. Preliminary results show that the flood, thermal and solute waves propagate downstream at varying rates leading to a lag between each wave and groundwater exchanges tend to impose different reduction of amplitudes for different waves. These findings provide insight regarding the longitudinal influences of hydropeaking occurring in a large fraction of rivers in the world which has important implications for water quality and the ecology of regulated rivers.

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Mar 28th, 2:35 PM Mar 28th, 2:40 PM

Longitudinal thermal and solute dynamics in regulated rivers

Logan Country Club

Dam releases increase river stage and reverse typical groundwater hydraulic gradients towards the river, which reestablish with the decline of river stage. As the flood, thermal, and solute waves travel downstream in a regulated river, the rate of change in amplitude will be affected both by surface water processes and groundwater exchanges. A dynamic instream water quality model was used to simulate the dynamics of flood, thermal, and solute waves transport through a 90 km portion of a regulated river. A series of flood, thermal, and solute waves of arbitrary magnitudes were released at the upstream boundary. Assuming a homogeneous and unconfined aquifer adjacent to the river, an analytical solution for the aquifer head response to periodic stream stage fluctuations was integrated into the surface water model to estimate the spatially and temporally variable groundwater exchanges and their impact on instream responses. Preliminary results show that the flood, thermal and solute waves propagate downstream at varying rates leading to a lag between each wave and groundwater exchanges tend to impose different reduction of amplitudes for different waves. These findings provide insight regarding the longitudinal influences of hydropeaking occurring in a large fraction of rivers in the world which has important implications for water quality and the ecology of regulated rivers.