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A Pre-Dam-Removal Assessment of Sediment Transport for Four Dams on the Kalamazoo River between Plainwell and Allegan, MichiganBy Atiq U. Syed, James P. Bennett, and Cynthia M. RacholIn collaboration with the U.S. Environmental Protection Agency, Region V, and the Michigan Department of Environmental QualityScientific Investigations Report 2004-5178 |
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The citation for this report, in USGS format, is as follows:
Syed, A.U., Bennett, J.P., and Rachol, C.M., 2005, A pre-dam-removal assessment of sediment transport for four dams on the Kalamazoo River between Plainwell and Allegan, Michigan: U.S. Geological Survey Scientific Investigations Report 2004-5178, 41 p.
For more information about USGS activities in Michigan, visit the USGS MI Water Science Center Home Page.
Four dams on the Kalamazoo River between the cities of Plainwell and Allegan, Mich., are in varying states of disrepair. The Michigan Department of Environmental Quality (MDEQ) and U.S. Environmental Protection Agency (USEPA) are considering removing these dams to restore the river channels to pre-dam conditions.
This study was initiated to identify sediment characteristics, monitor sediment transport, and predict sediment resuspension and deposition under varying hydraulic conditions. The mathematical model SEDMOD was used to simulate streamflow and sediment transport using three modeling scenarios: (1) sediment transport simulations for 730 days (Jan. 2001 to Dec. 2002), with existing dam structures, (2) sediment transport simulations based on flows from the 1947 flood at the Kalamazoo River with existing dam structures, and (3) sediment transport simulations based on flows from the 1947 flood at the Kalamazoo River with dams removed. Sediment transport simulations based on the 1947 flood hydrograph provide an estimate of sediment transport rates under maximum flow conditions. These scenarios can be used as an assessment of the sediment load that may erode from the study reach at this flow magnitude during a dam failure.
The model was calibrated using suspended sediment as a calibration parameter and root mean squared error (RMSE) as an objective function. Analyses of the calibrated model show a slight bias in the model results at flows higher than 75 m3/s; this means that the model-simulated suspended-sediment transport rates are higher than the observed rates; however, the overall calibrated model results show close agreement between simulated and measured values of suspended sediment.
Simulation results show that the Kalamazoo River sediment transport mechanism is in a dynamic equilibrium state. Model results during the 730-day simulations indicate significant sediment erosion from the study reach at flow rates higher than 55 m3/s. Similarly, significant sediment deposition occurs during low to average flows (monthly mean flows between 25.49 m3/s and 50.97 m3/s) after a high-flow event. If the flow continues to stay in the low to average range the system shifts towards equilibrium, resulting in a balancing effect between sediment deposition and erosion rates.
The 1947 flood-flow simulations show approximately 30,000 m3 more instream sediments erosion for the first 21 days of the dams removed scenario than for the existing-dams scenario, with the same initial conditions for both scenarios. Application of a locally weighted regression smoothing (LOWESS) function to simulation results of the dams removed scenario indicates a steep downtrend with high sediment transport rates during the first 21 days. In comparison, the LOWESS curve for the existing-dams scenario shows a smooth transition of sediment transport rates in response to the change in streamflow. The high erosion rates during the dams-removed scenario are due to the absence of the dams; in contrast, the presence of dams in the existing-dams scenario helps reduce sediment erosion to some extent.
The overall results of 60-day simulations for the 1947 flood show no significant difference in total volume of eroded sediment between the two scenarios, because the dams in the study reach have low heads and no control gates. It is important to note that the existing-dams and dams-removed scenarios simulations are run for only 60 days; therefore, the simulations take into account the changes in sediment erosion and deposition rates only during that time period. Over an extended period, more erosion of instream sediments would be expected to occur if the dams are not properly removed than under the existing conditions. On the basis of model simulations, removal of dams would further lower the head in all the channels. This lowering of head could produce higher flow velocities in the study reach, which ultimately would result in accelerated erosion rates.
Abstract
Introduction
Purpose and Scope
Previous Studies
Description of the Study Reach
Field Data Collection Methods
Transect Surveying and Sediment Coring
Suspended- and Bed-Sediment Data Collection
Description of the Sediment-Transport Model
Flow Simulations
Bedload Transport
Suspended-Sediment Transport
Model Input Data Structure
Network-Description File
Boundary-Condition File
Computation of Manning’s Roughness Coefficient
Flow Analysis
Sediment-Transport Model Calibration
Simulations of Sediment Transport
Sediment-Transport Simulations with Existing Dam Structures
Total Volume and Median Size Distribution of Instream Sediment
Sediment Erosion and Deposition Rates During the Simulation Period
Sediment-Transport Simulation Results, Using Flows from the 1947 Flood with Existing Dam Structures and Dams Removed
Asumptions and Limitations of the Sediment-Transport Model
Summary and Conclusions
Acknowledgments
References Cited
Glossary
Appendix 1. Suspended- and Bed-Sediment Data 2001–2002 Kalamazoo River, Michigan
Appendix 2. Simulated Streamflow Data for the 1947 Flood at the Plainwell Streamgage, Plainwell, Michigan
Appendix 3. Computed Values of Manning’s Roughness Coefficient for the Alluvial Section of the Kalamazoo River, Michigan
1-3.Maps showing:
1.Kalamazoo River study reach and location of four dams
2.Modeled river channel and transect locations at the A, Plainwell; B, Otsego City; C, Otsego; and D, Trowbridge Dams
3–19.Graphs showing:
3.Definition of flow-related variables (from Bennett, 2001)
4.Comparison of model-input streamflows recorded at the Plainwell streamgage and model-simulated streamflows to check for continuity
5.Simulated and observed streamflows
6.Minimized objective function for McLean coefficient as a model calibration parameter
7.Calibrated model residuals (observed minus simulated values), achieved with a McLean coefficient value of 0.004
8.Observed and simulated suspended sediment transport rates after calibration
9.Simulated total sediment-transport rates during the simulation period January 2001 to December 2002
10.Changes in bed elevations and sediment d50 (median bed-sediment size, such that 50 percent of the particles are finer) during the 730-day model simulations for channel 4, cross section-27
11.Changes in bed elevations and sediment d50 (median bed-sediment size, such that 50 percent of the particles are finer) during the 730-day model simulations for channel 9, cross section-50
12.Changes in bed elevations and sediment d50 (median bed-sediment size, such that 50 percent of the particles are finer) during the 730-day model simulations for channel 11, cross section-64
13.Changes in bed elevations and sediment d50 (median bed-sediment size, such that 50 percent of the particles are finer) during the 730-day model simulations for channel 12, cross section-80
14.Changes in bed elevations and sediment d50 (median bed-sediment size, such that 50 percent of the particles are finer) during the 730-day model simulations for channel 13, cross section-88
15.Changes in bed elevations and sediment d50 (median bed-sediment size, such that 50 percent of the particles are finer) during the 730-day model simulations for channel 13, cross section-93
16.Simulated total sediment transport rates for 1947 flood with current dam structures
17.Simulated total sediment transport rates for 1947 flood with dams removed conditions
18.Application of locally weighted regression smoothing (LOWESS) function to simulation results of 1947 flood flow with dams-removed scenario show an uncontainable trend in sediment transport rates during the first 21 days
19.Application of locally weighted regression smoothing (LOWESS) function to simulation results of 1947 flood flow with existing-dams scenario
1.Volume of instream sediment in the backwater section of each dam
2.Simulated sediment transport rates during the high-flow events between January 2001 and December 2002
3.Simulated sediment transport rates during the 1947 flood simulations
4.Sediment mass-balance errors reported by the model during simulation
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