Utah Lake Model: Hydrodynamics And Sediment Transport

Utah Lake Model:Hydrodynamics andSediment TransportUtah Lake Water Quality StudyScience Panel Meeting 8/8/2018Nicholas von Stackelberg

Presentation Outline1) Model Selection2) EFDC Model Formulationa) Hydrodynamicsb) Sediment Transport3) EFDC Preliminary Model Build4) Data Collection for EFDC Model CalibrationDivision of Water Quality2

Model Selection

Utah Lake Model Selection Formed model sub-workgroup forstakeholder input Evaluated potential models to meetobjectives and selection criteria Preference: Complex, 3D model to capture processes Freeware, public domain for transparency Selected coupled model: Hydrodynamics – EFDC Water Quality – WASP Models subsequently selected byUniversity of Utah research team fordevelopment through EPA ORDgrantDivision of Water Quality4

Need for Separate Hydrodynamic Model Hydrodynamics integrated into WASP are 1-D only Lateral mixing and circulation highly dependent on windinduced currents Sediment deposition/resuspension identified as key process ineutrophication of shallow lakes Suspended sediment alters light penetration Phosphorus adsorbed to sediment can be released whenresuspended Sediment resuspension dependent on wave height/frequencyand shear stressDivision of Water Quality5

EFDC – WASP Model Linkage EFDC generates WASP hydrodynamic linkage file Water depth Water velocity in three directions (x, y, z) Additional EFDC state variables to be simulatednot linked to WASP Salinity Temperature Cohesive Inorganic SedimentDivision of Water Quality6

EFDC Model Formulation

EFDC (Environmental Fluid Dynamics Code) EPA and NOAA supported freeware software 3-D hydrodynamic model Widely applied to rivers, lakes, reservoirs, wetlands, estuaries,and coastal ocean regions Physical characteristics of the waterbody Horizontal grid: Cartesian or curvilinear-orthogonal Vertical grid: sigma terrain following Solves transport equations for water velocity and depth,salinity, temperature, suspended cohesive and non-cohesivesediment, dissolved and adsorbed contaminants, and a dyetracer Simulates drying and wetting in shallow areas, representationof hydraulic control structures, and vegetative resistanceDivision of Water Quality8

HydrodynamicsSigma terrain following vertical coordinatesH h ηz* zHConservation of mass: Continuity Equation H Hu Hv w * 0 t x y zConservation of momentum: Navier-Stokes EquationAccumulationAdvectionCoriolis Hu Huu Hvu wu * fHv t x y z p zb* H H z x x xPressureBuoyancy p AV u u u 22 12 HAH * * c p Dp ( u v ) u HAH* x y y z z H z x Verticalmomentum istanceDivision of Water Quality9

EFDC Sediment Transport Simulates wind-induced currents and wave effects on lakebedshear stress either internally or through externally linked model Simulates multiple size classes of cohesive and non-cohesivesediment Sediment processes function library has a wide range ofaccepted parameterizations for settling, deposition,resuspension and bed load transport Sediment bed is represented by multiple layers Dynamic prediction of bed layer thickness, void ratio and porewater advection The sediment transport component can operate in amorphological mode with full coupling with the hydrodynamiccomponent to represent dynamic evolution of bed topographyDivision of Water Quality10

Cohesive SedimentsSource: Ji 2008Division of Water Quality11

Cohesive Sediment Transport Processes1) Suspension and Transport2) Flocculation and Settling3) Deposition4) Bed Consolidation5) Erosion and ResuspensionDivision of Water Quality12

Sediment TransportSource: Ji 2008Division of Water Quality13

Flocculation and Settling Key parameter: settling velocity Six options that relate effective settling velocity tosuspended sediment concentration and:1. Reference settling velocity, reference suspended sedimentconcentration, and empirical coefficient α (Ariathurai and Krone1976)2. Empirical coefficients a, b, m, & n (Hwang and Mehta 1989)3. Floc diameter, which is related to turbulent shear stress andempirical coefficients αf, B1, & B2 (Ziegler and Nisbet 1994, 1995)4. Vertical shear of the horizontal velocity (Shrestha and Orlob 1996)5. Flocculation (Lick et al. 1993)6. Flocculation with advection (Lick et al. 1993)Division of Water Quality14

DepositionKey parameter: critical shear stress for deposition, τcdJd – depositional fluxws – settling velocitySd – near bed sediment concentrationτb – bed shear stressDivision of Water Quality15

Wind WavesSource: Ji 2008 Simulates wind-induced currents and wave effects on lakebedshear stress either internally or through externally linked model(i.e. SWAN)Division of Water Quality16

Surface Erosion and ResuspensionKey parameters: critical shear stress for erosion, τce andsurface erosion rate, dme/dtConsolidated bedorPartiallyconsolidated bedJr – surface erosion fluxdme/dt – surface erosion rate per unit surface area of the bedτb – bed shear stressα, β, γ – site specific parametersDivision of Water Quality17

Surface Erosion and ResuspensionCritical shear stress for erosion, τce and surface erosionrate, dme/dt are dependent on:1. Shear strength2. Sediment physical properties, i.e. bulk density3. Water content4. Salt content5. Ionic species6. pH7. TemperatureEFDC allows specification of constant value or dependenton bulk density, ρbDivision of Water Quality18

Mass Erosion and ResuspensionKey parameter: shear strength, τsJr – mass erosion fluxmme – surface erosion rate per unit surface area of the bedTme - transfer time scale for the mass erosionτb – bed shear stressEstimation of shear strength: τs asρb bsDivision of Water Quality19

Sediment Bed ConsolidationSource: Ji 2008 Four options for simulating consolidation of sediment bed:1. Constant porosity bed2. Simple consolidation rate model3. Finite strain consolidation theory with specified void ratio at the water columnsediment bed interface4. Finite strain consolidation theory with no excess pore pressure at the watercolumn-sediment bed interfaceDivision of Water Quality20

EFDC Preliminary Model BuildWater Year 2006-2015

EFDC Input Requirements1) Inflows flow water temperature suspended sediment salinity2) Outflows – Jordan River3) Meteorology precipitation evaporation air temperature relative humidity solar radiation wind4) Lake bathymetry5) Lake bottom surfaceroughness6) Vegetative resistanceDivision of Water Quality22

Utah Lake Preliminary Grid Cartesian grid 500 m cell sizeRecommended by Callister 2008 1,694 grid cells 5 vertical layersVariable depth (sigma stretched) 8,470 output cubesDivision of Water Quality23

Data Collectionto Support ModelCalibration

Calibration Approach Constituents Water depth/water surface elevationWater velocityWave heightSuspended solidsWater temperatureSalinityCollect approx. 6-9 months of observed dataEstimate parameters using measured dataManually adjust calibration parametersMinimize error between predicted and observeddata using graphical and statistical testsDivision of Water Quality25

Data Collection - Hydrodynamics Water Surface Elevation CUWCD maintains stage gage at Utah Lake Pump House Deploy pressure transducer on south end of lake? Tributary Inflows Deploy pressure transducers at each major inflow (DWQ) USGS maintains flow gages at Provo River, Hobble Creek Outflow DWR publishes flow records at Jordan River Narrows Weather Station Nearby stations: Provo Municipal Airport, BYU Provo Deploy on-lake or near shore? Evaporation DWR publishes evap records using Blaney-Criddle Calculate using Penman-MonteithDivision of Water Quality26

Data Collection - Hydrodynamics Acoustic Doppler Current Profiler(ADCP) Measure velocities throughout water column Measure wave height Measure bathymetry – boat mountedADV Acoustic Doppler Velocimeter(ADV)ADCPWQ sonde Measure velocity at water column-sedimentinterface Water quality sonde Temperature, conductivity, pH, DO, turbidity,chlorophyll a Sediment trapSediment trapMounting frame Estimate sediment resuspension Grab sampling Phosphorus, TSS, VSS Deployment One month at six locationsDivision of Water Quality27

Data Collection – Sediment Turbidity and TSS of water column Resuspension rate Sediment trap Sediment characterization Surficial sediment cores at each ADCPlocation Measure properties D50, particle size distributionBulk densityWater contentMineralogyOrganic contentSodium Adsorption Ratio (SAR)Cation Exchange Capacity (CEC)Division of Water Quality28

How EFDC Could be Used to SupportWater Quality Study Provide critical hydrodynamic information toWASP nutrient model Improve understanding of sediment depositionand resuspension relationship to wind and waves Help support estimates of internal P loadingDivision of Water Quality29

Nicholas von Stackelberg, P.E.Utah Dept of Environmental Quality(801) 536-4374nvonstackelberg@utah.gov

Cohesive Sediment Transport Processes 1)Suspension and Transport 2)Flocculation and Settling 3)Deposition 4)Bed Consolidation 5)Erosion and Resuspension 12. Division of Water Quality Sediment Transport 13 Source: Ji 2008. Division of Water Quality Flocculation and Settling Key parameter: settling velocity Six options that relate effective .