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WLRD Science Seminar

WLRD Science Seminar. Sammamish River Water Quality Model Status Report November 19, 2002. Sammamish-Washington Analysis and Modeling Program. Sammamish River Model. CE-QUAL-W2 Model. 2-D model Laterally averaged No zooplankton, macrophytes, sediment diagenesis

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WLRD Science Seminar

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  1. WLRD Science Seminar Sammamish River Water Quality Model Status Report November 19, 2002

  2. Sammamish-Washington Analysis and Modeling Program

  3. Sammamish River Model

  4. CE-QUAL-W2 Model • 2-D model • Laterally averaged • No zooplankton, macrophytes, sediment diagenesis • Epiphyton and riparian shade model added recently

  5. Model Calibration

  6. Model Calibration

  7. Model Calibration

  8. Model Calibration

  9. Model Calibration

  10. Model Calibration

  11. Ongoing Temperature Monitoring

  12. Ongoing Water Surface Profiling

  13. Shade Inputs

  14. Water Quality Model Development

  15. Water Quality Locators >=Year 2000

  16. Water Quality Model Boundary Conditions

  17. Water Quality Model Results

  18. Water Quality Model Diurnal DO and pH Fluctuations

  19. Recommendations • Groundwater data collection • Ungaged tributary input refinement • River water surface elevations/travel time studies • Mainstem river temperature data collection • Additional mainstem water quality stations including storm sampling and chl a meas. • Tributary organic carbon monitoring • Continuous DO/pH monitoring

  20. Model Calibration Steps • Water Balance/Hydraulics • Temperature • Water quality • Conservative constituents • Nutrients • DO/pH • Light penetration • Phytoplankton • Revisit temperature and repeat water quality

  21. Total dissolved solids Multiple arbitrary constituents Conservative tracer Residence time Indicator bacteria Ammonium Nitrate Dissolved inorganic P Dissolved silica Particulate biogenic silica Multiple inorganic suspended solids Total iron Labile DOM Refractory DOM Labile POM Refractory POM Multiple CBOD groups Multiple algal groups Dissolved oxygen Total inorganic carbon Alkalinity Model State Variables

  22. Total, dissolved, and particulate organic carbon Total, dissolved, and particulate organic nitrogen Total Kjedahl nitrogen Total nitrogen Total, dissolved, and particulate organic P Total suspended solids Total inorganic suspended solids Dissolved oxygen saturation Algal production Chlorophyll a Total algal biomass pH Carbon dioxide Bicarbonate Carbonate Model Derived Variables

  23. Hydrodynamic Output • Horizontal and vertical velocity • Temperature • Density • Vertical eddy viscosity • Vertical shear stress • Advection of vertical momentum • Advection of longitudinal momentum • Longitudinal momentum • Horizontal density gradient • Horizontal pressure gradient • Shear at top of layer • Shear at the bottom of layer • Gravity term due to channel slope

  24. Model Data Needs • Channel cross sections/bathymetry • Meteorology (air temp, dew point, wind, clouds, observed solar radiation) • Measured tributary inflow quantity and quality • Unmeasured (including gw?) inflow quantity and quality • Calibration data (quantity/quality)

  25. Water Quality Boundary Conditions • TDS = 0.55 x Spec. Cond. • Dissolved silica = 7.2 mg/L • Particulate biogenic silica = 2.0 mg/L • Ammonium, nitrate, diss. P from observations • TIC from pH and alkalinity measurements • Inorganic suspended solids = TSS - POM* • POM = Particulate organic matter …but organic carbon concentration not measured

  26. Water Quality Boundary Conditions • Assume tributary TOC = 5 mg/L • Assume 40 % of organic matter is carbon • Assume 90 % of TOC is dissolved • Assume 30 % of TOC is labile • Therefore: • LDOM = TOC x 2.5 x 0.9 x 0.3 • RDOM = TOC x 2.5 x 0.9 x 0.7 • LPOM = TOC x 2.5 x 0.1 x 0.3 • RPOM = TOC x 2.5 x 0.1 x 0.7

  27. Water Quality Boundary Conditions • Assume three algal groups (diatoms, greens, blue-greens) for initial modeling • Assume algae contributed only at the upstream boundary with Lake Sammamish • Assume conversion of chlorophyll a to algal biomass (mg/L) = chl a (µg/L) x 0.065 • Assume fraction of influent algal biomass that is: • Diatoms = 0.5 • Greens = 0.3 • Blue-greens = 0.2

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