Simulation of sediment transport due to dam removal and control of morphological changes
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Simulation of Sediment Transport due to Dam Removal and Control of Morphological Changes. Yan Ding* and Eddy Langendoen** * National Center for Computational Hydroscience and Engineering, The University of Mississippi, University, MS 38677, U.S.A.

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Simulation of Sediment Transport due to Dam Removal and Control of Morphological Changes

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Simulation of sediment transport due to dam removal and control of morphological changes

Simulation of Sediment Transport due to Dam Removal and Control of Morphological Changes

Yan Ding* and Eddy Langendoen**

* National Center for Computational Hydroscience and Engineering,

The University of Mississippi, University, MS 38677, U.S.A.

**Channel and Watershed Processes Research Unit

USDA Agricultural Research Service

National Sedimentation Laboratory, Oxford, MS 38655, U.S.A.


Outline

Outline

Introduction

Numerical Simulation of Post Dam Removal Sediment Dynamics Along the Kalamazoo River Between Otsego and Plainwell, Michigan

Numerical Simulation of Morphological Changes due to Marmot Dam Removal in Sandy River, Oregon

Preliminary Study on Optimal Control of Sediment Release in the Dam Removal Process

Concluding Remarks


Dam removal impact and river restoration

Dam Removal Impact and River Restoration

Financial issue : Operating and maintenance costs outweigh the benefits - including hydropower, flood control, irrigation, or recreation,

Functional issue: where the dam no longer serves any useful purpose,

Ecological issues: restoring flows for fish and wildlife, reinstating the natural sediment and nutrient flow,

Safety issues: eliminating safety risks,

Recreational issues: restoring opportunities for recreation. 

The impacts of removal have been addressed by different studies. Generally they can be divided into main categories.

(1) Short-Term Ecological Impacts of Dam Removal Sediment Release, Increased Sediment Concentration and Contaminated Sediment, and

(2) Long-Term Impacts of Dam Removal (Flow change regimes, temperature, sediment transport and water quality)


Simulation of sediment transport due to dam removal and control of morphological changes

Case Study: Numerical Simulation of Post Dam Removal Sediment Dynamics Along the Kalamazoo River Between Otsego and Plainwell, Michigan


Simulation of sediment transport due to dam removal and control of morphological changes

DA: 2,020 sq mi

Relief: 686 ft


Background

Background

  • Otsego City Dam

    • Built in 1840s to create freight business

    • Papermill was constructed in 1880s and remains in operation

    • Repaired and rebuild over time

    • 151 ft x 13 ft

  • Plainwell Dam

    • Built around 1900 to provide power

    • Power generators decommissioned in mid 1960s

    • Superstructure and part of spillway removed in mid 1980s

    • 172 ft x 14 ft


Background cont

Background (cont.)

  • PCB contaminated sediments deposited in the dam impoundments

    • Banks: 5 mg/kg – 82 mg/kg

    • Floodplain: 3 mg/kg – 84 mg/kg

  • MDNR interested in removing the dams

  • MDEQ and EPA interested in understanding present condition and potential concerns (bank erosion)


Summary of studies

Summary of Studies

  • LimnoTech

    • KALSIM: HEC6, Bank erosion based on Osman & Thorne (1988), PCB fate model

  • USGS

    • Survey transects, flow velocity, instream sediments

    • SEDMOD (Bennett)

    • Channel restoration design

  • NSL

    • Identify streambank erosion problems: static model (USGS) and dynamic model (NSL)

    • Collect streambank material properties: erodibility and shear strength


Simulation of sediment transport due to dam removal and control of morphological changes

Impoundment Area: 3,290,000 sq ft

Volume of deposit: 457,000 cu yd (56% main-stem channel)


Simulation of sediment transport due to dam removal and control of morphological changes

Impoundment Area: 701,000 sq ft

Volume of deposit: 77,600 cu yd


Modeling scenarios

Modeling Scenarios

  • Dams In (no change, DI)

  • Dams Out (DO)

  • Design (D)

  • 38-year long discharge time series constructed from 1984-2003 period of record

  • Simulation period: 2000-2037


Concepts conservational channel evolution and pollutant transport system

Output:

Changes in channel geometry

Time series of hydraulic variables and sediment yield

Input:

Channel geometry

Composition of bed and bank materials

Erosion resistance and shear strength of bed and bank materials

Rates of flow and sediments entering the channel

Bendway weir

Bed evolution and sediment transport

Streambank erosion

Flow hydraulics

CONCEPTS – CONservational Channel Evolution and Pollutant Transport System

CONCEPTS simulates long-term response of channels to loadings of water and sediments, and to instream structures


Simulation of sediment transport due to dam removal and control of morphological changes

BST – shear strength

Jet test – erodibility


Simulation of sediment transport due to dam removal and control of morphological changes

CHANNEL MODEL


Simulation of sediment transport due to dam removal and control of morphological changes

11%

6%

108%

5%

77%

8%

9%

90%

11%

74%

1%

12%

17%

84%

99%

4%

10%

95%

5%

6%


Di results

DI - RESULTS


Simulation of sediment transport due to dam removal and control of morphological changes

VALIDATION


Simulation of sediment transport due to dam removal and control of morphological changes

Dams In Scenario


Simulation of sediment transport due to dam removal and control of morphological changes

POC4 – Dams In Scenario


Simulation of sediment transport due to dam removal and control of morphological changes

G8 – Dams In Scenario


Do results

DO - RESULTS


Simulated bed adjustment

Simulated Bed Adjustment

  • Dams Out Scenario

Plainwell Dam

Otsego City Dam


Simulated bed adjustment cont

Remobilization

& transport

Deposition

Upstream

migration

Rapid

incision

Simulated Bed Adjustment (cont.)

  • Dams Out Scenario


Simulated top width adjustment

Followed by

widening

Narrowing

Simulated Top Width Adjustment

  • Dams Out Scenario


Simulation of sediment transport due to dam removal and control of morphological changes

G1

G2


Simulation of sediment transport due to dam removal and control of morphological changes

G5

G6


D results

D - RESULTS


Simulation of sediment transport due to dam removal and control of morphological changes

P17

G1


Simulation of sediment transport due to dam removal and control of morphological changes

POC6

POC4


Streambank erosion comparison

Streambank Erosion – Comparison


Average annual load comparison

Average Annual Load – Comparison


Simulation of sediment transport due to dam removal and control of morphological changes

Case Study: Numerical Simulation of Morphological Changes due to Marmot Dam Removal in Sandy River, Oregon

Objective of control in this case:

Validation of sediment transport model

Minimize the morphological changes (erosion and deposition) at downstream by diverting extra sediments from the reservoir (dredging?)


Marmot dam removal in the sandy river oregon

Marmot Dam Removal in the Sandy River, Oregon

http://www.youtube.com/watch?v=i1NI2ia3nDw


Integrated watershed channel network modeling with cche1d

Rainfall-Runoff Simulation

Upland Soil Erosion

(AGNPS or SWAT)

Channel Network and

Sub-basin Definition

(TOPAZ)

Digital Elevation

Model (DEM)

Channel Network Flow and Sediment Routing

(CCHE1D)

Integrated Watershed & Channel Network Modeling with CCHE1D

Principal Features

Dynamic Wave Model for Flood Wave Prediction

  • Hydrodynamic Modeling in Channel Network

  • Non-uniform Total-Load Transport

  • Non-equilibrium Transport Model

  • Coupled Sediment Transport Equations Solution

  • Bank Erosion and Mass Failure

  • Several Methods for Determination of Sediment-Related Parameters

where Q = discharge; Z=water stage;

A=Cross-sectional Area; q=Lateral outflow;

=correction factor; R=hydraulic radius

n = Manning’s roughness

  • Boundary Conditions

  • Initial Conditions (Base Flows)

  • Internal Flow Conditions for Channel Network


Cche1d sediment transport model

CCHE1D Sediment Transport Model

Principal Features

Non-equilibrium transport of non-uniform sediments

  • Non-uniform Total-Load Transport

  • Non-equilibrium SedTran Model

  • Coupled SedTran Equations Solution (Direct Solution Technique)

  • Bank Erosion and Mass Failure

  • Several Methods for Determination of Sediment-Related Parameters

A=cross-section area; Ctk=section-averaged sediment concentration of size class k; Qtk=actual sediment transport rate; Qt*k=sediment transport capacity; Ls=adaptation length andQlk= lateral inflow or outflow sediment discharge per unit channel length; Ut=section averaged velocity of sediment


Sandy river longitudinal profiles

Sandy River Longitudinal Profiles

Computational Reach

Major J. J. et al (2012), USGS Technical Report, http://pubs.usgs.gov/pp/1792/


Reservoir sediment property

Reservoir Sediment Property

Reservoir deposition profile

(Source: PGE photogrametry, 1999)

Reservoir sediment size composition (Stillwater Science, 1999)


Simulation model parameters cche1d

Simulation Model Parameters: CCHE1D


Sediment size classes used in the simulations

Sediment size classes used in the simulations


Boundary conditions for model validation

Boundary Conditions for Model Validation

Simulation Period 10/19/2007 – 09/30/2008

Downstream Water Depth Hydrograph

Upstream Discharge Hydrograph


Simulation parameters and calibrated values

Simulation Parameters and Calibrated Values


Simulation of sediment transport due to dam removal and control of morphological changes

Simulation Results: 1-Year Bed Evolution


Long term morphological changes 10 year

Long-Term Morphological Changes: 10-Year

Water year series selected for simulation


Optimal control of sediment transport and morphological changes

Optimal Control of Sediment Transport and Morphological Changes

  • The developed model is coupling an adjoint sensitivity model with a sediment transport simulation model (CCHE1D) to mitigate morphological changes.

  • Different optimization algorithms have been used to estimate the value of the diverted or imposed sediment along river reach (control actions) to minimize the morphological changes under different practices and applications.

Sediment Control Model

Sediment Transport Simulation Model

  • CCHE1D

Optimization Model

  • Adjoint sensitivity model


Adjoint equations for the full nonlinear saint venant equations

Adjoint Equations for the Full Nonlinear Saint Venant Equations

According to the extremum condition, all terms multiplied by A and Q can be set to zero, respectively, so as to obtain the equations of the two Lagrangian multipliers, i.e, adjoint equations (Ding & Wang 2003)


Sediment transport control actions and sensitivity

Sediment Transport Control Actions and Sensitivity

Qt(0,t)

  • Adjoint Equation for Sed. Control

Qt(L,t)

  • Lateral Sediment Discharge

Lateral Outflow ql

  • Upstream Sediment Discharge

  • Downstream Sediment Discharge

  • In this study, fS is not a function in ql, thus the sensitivity is based on the values of λS.


Objective function for flood control

Objective Function for Flood Control

where T=control duration; L = channel length; t=time; x=distance along channel; Z=predicted water stage; Zobj(x) =maximum allowable water stage in river bank (levee) (or objective water stage); x0= target location where the water stage is protective;  = Dirac delta function

Zobj

To evaluate the discrepancy between predicted and maximum allowable stages, a weighted form is defined as


Reservoir sediment release control

Reservoir Sediment Release Control

Xiao Land Di Reservoir, Yellow River, China

Yellow River

  • Reservoir Sediment Release at 9:00am,

  • Clear Water Release at 10:00am, 6/19/2010


Optimization model objective function for morphological control

Optimization Model: Objective Function for Morphological Control

Consider the equation of morphological change:

The objective function for control of morphological changes can be written as

and measuring function as,

(9)

(10)

where

can be taken equal to

i.e. the sediment transport capacity.

It means that for minimizing morphological change in a cross section, it is needed to make sediment transport rate in the section close to the sediment transport capacity.


Simulation of sediment transport due to dam removal and control of morphological changes

Hypothetical Case (2): Reservoir Sediment Release

Excess Erosion Problem Downstream

20 m

1:2

1:2

Given Q = Q(t)

10 m

S0=0.5 %

Qs= ?

L=7 km

Control Objective: To minimize morphological change downstream

Simulation time = 1 year

Sediment Properties: Uniform sediment of d = 20 mm

Bed load adaptation length = 125 m,

suspended load adaptation coefficient = 0.1, and

mixing-layer thickness = 0.05 m.


Simulation of sediment transport due to dam removal and control of morphological changes

Hypothetical Case (2) – Scenario (3): Model Results

Morphological changes after storm

Upstream flood flow (given)


Optimal sediment diversion after dam removal

Optimal sediment diversion after Dam Removal

Engineering difficulty: how to divert the sediments based on the optimal schedule?


Concluding remarks

Concluding Remarks

1-D channel evolution models are capable of simulating sedimentation in reservoir sediment release process due to dam removals in rivers.

Coupling with simulation model of flow and sediment transport (CCHE1D), adjoint optimization model can achieve the best control of sedimentation due to the sediment releases.

Streambank erosion may be significant if dams are removed.

Further study:

Fine-grained deposits (cohesive?), Parent (pre-dam) bed material

Rejuvenation of side channels, Vegetation, Uncertainty analysis, and application of sediment conotrl


Acknowledgements

Acknowledgements

The research of CCHE1D was partly supported by the USDA Agriculture Research Service under Specific Research Agreement No. 58-6408-1-609 (monitored by the USDA-ARS National Sedimentation Laboratory) and The University of Mississippi.


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