US Army Corps of Engineers Detroit District Remaining Capacity in Great Lakes Reservoirs
Storage Capacity Behind Great Lakes Dams Field Data and Modeling Motivation for project Project overview Data and methods Results from Lake Rockwell
US Army Corps of Engineers Detroit District Fluvial Sediment Sand From Watershed = 880,000 cy/yr 250,000 Channel Depth (ft) 1903 1939 1954 16 18 21 24 at entrance, 21 in channel 1983 Dred dge volume (cubic yards) 200,000 150,000 100,000 Total Average 37,500 53,000 86,000 82,000 35,000 (cy/yr) ~1902 1903~1945 1946~1970 1971~1991 1992~Present Total maintenance Entrance channel Inner harbor Entrance channel dredging g trend 50,000 0 1840 1860 1880 1900 1920 1940 1960 1980 2000 2020 Year ~20,000 cy/yr
US Army Corps of Engineers Detroit District Sediment Stored Behind Dams Berrien Springs Dam
US Army Corps of Engineers Detroit District Study Objectives Develop an understanding of the storage capacity for sediment behind dams in the Great Lakes through monitoring, modeling and assessment of historic documents. Understand and quantify the issues that influence the production and deposition of sediment in reservoirs How much storage capacity and time is left? Extrapolate this to remaining watersheds in Great Lakes Determine the sediment loading rate to the Great Lakes
US Army Corps of Engineers Detroit District Dam Capacity Study Tasks Select 10 Reservoirs to study Through historical analysis/modeling determine: Present Sediment Erosion, Storage, and Delivery Pre-Settlement Sediment Erosion, Storage, and Delivery Field data collection Sediment Cores Reservoir Bathymetry Sediment Rating Curves Storage Capacity Analysis Long-term simulation modeling Linear Regression modeling of sediment accumulation
Reservoir Selection
US Army Corps of Engineers Detroit District Reservoir Sedimentation 1. Continuous Sediment Trapping: Bedload and much of suspended load is trapped. 2. Partial Sediment Balance: Bed load is trapped, but fine sediments is removed in large flood events. Submerged floodplains form. 3. Full Sediment Balance: Long-term equilibrium of both bedload and suspended load occurs. From: Morris, Annandale, and Hotchkiss, 2008
Sedimentation rates using multiple approaches: determination of the sedimentation rate of an impoundment by dating sediment cores using Cesium 137 ( 137 Cs) and Lead 210 ( 210 Pb). evaluation of sediment accumulation via analysis of historic bathymetric maps versus current bathymetric maps. USGS sediment gages evaluation of sediment yield modeling.
Reservoir Selection Characteristics and Rank of Importance
Reservoir Selection 2,271 dams that were initially assessed <50 impoundments contained all of the reservoir selection characteristics The 10 reservoirs are located in Indiana, Michigan, New York, Ohio, and Wisconsini Represent a variety of watersheds types: urban, agriculture, forested
Field ldprocedures The field procedures were designed so that work could be completed at each impoundment in about three days vibracore sediment sampling a bathymetric survey velocity transects of streams that feed each impoundment surface water sampling (TSS testing)
WSU Core Processing Each 4-inch diameter core was frozen and sliced top 10 centimeters of each core, 1-centimeter thick slices were selected for dating; followed by 2-centimeter thick layers for dating Gamma Spectrometer
Sediment Accumulation Rates: 137 210 137 Cs and 210 Pb Riley Dam, RD-6 210 Pb Linear Sedimentation Rate 0.55 cm/yr 137 Cs Peak Linear Sedimentation Rate 0.57 cm/yr Application to a wide variety of projects
Velocity Transects and Bathymetry
Sontek km9s SonTek kriversurveyor Acoustic Doppler Profiler (ADP) system designed to measure river discharge 3-dimensional water currents, depths, and bathymetry. nine-beam system two sets of four profiling beams one vertical beam
Bathymetric Transects Green Lake, Wisconsin
Results from Lake Rockwell Bathymetric Surveys Historic and Present Day USGS Sediment Gage Data Corps of Engineers Great Lakes Regional Sediment Data Radionuclide Dating of Sediments
Historic Contours
Sediment Yield Calculation
Sedime ent Load Tons/day USGS 04202000 160 140 120 100 80 60 40 20 0 Qs = 0.126(Qw) 0.739 R² = 0.666 0 1,000 2,000 3,000 Discharge cfs
What do the sediments reveal regarding sediment accumulation rates? Radionuclide Dating (Baskaran, et. al) 4 of 11 Sediment Cores Analyzed (2 partially complete at present) Sedimentation Accumulation Rate of Approximately 0.35 cm/year; 34.3 cm Sedimentation Accumulation Rate of Approximately 0.35 cm/year; 34.3 cm accumulated since dam construction
Lake Rockwell and Region Sediment Accumulation Comparisons Method Sediment Load (Tons per year) Bathymetric Data 17,980 Sediment Gages 19,300 Dated sediment accumulation rate uniformly applied over reservoir 19,550 Sediment Regional Curves 20,500
Great Determination Lakes of Sediment Accumulation Yield Curve Rates
Project Status Ongoing work (to be complete in 2014) Sediment core dating Sediment SWAT modeling Estimate the remaining storage capacity behind dams Capacity will be quantified in terms of time remaining and volume remaining
US Army Corps of Engineers Detroit District Who Should Be Interested in These Results? Anyone doing dredging Anyone building (or removing) a dam Anyone building an impoundment (retention basin, ice trap, et c.) Anyone concerned about downstream impacts of sediment o Fisheries managers o Flooding due to aggradation o Water treatment plants o Power companies o And many others! We have created a landscape that is shedding sediment at an artificially high rate. The downstream delivery of this sediment is being temporarily arrested by the 2581 dams in Michigan but for how long?
US Army Corps of Engineers Detroit District Questions? Contact: Dr. Jim Selegean, P.E., P.H. U.S. Army Corps of Engineers, Detroit District i t Great Lakes Hydraulics and Hydrology Office 477 Michigan Ave Detroit, MI 48226 313.226.6791 james.p.selegean@usace.army.mil