1. Monitoring and Simulating 3-D Water Circulation at the Confluence of the Snake and Clearwater Rivers Christopher B Cook MC Richmond, MD Bleich, SP Titzler, and B Dibrani September 22, 2004 Richland, WA BPA Project 2002-027-00

2. 2 Snake and Clearwater R. Confluence Border of WA and ID.

3. 3 Circulation Dynamics at the Confluence Determined by discharge and density (primarily a function of temperature at this location). Mixing processes can be: Observed by collecting field data. Modeled numerically. Approximated by examining the momentum balance between the two rivers. At Snake/Clearwater confluence, weve discovered four modes based upon Q ratio and temp delta (Δ).

4. 4 2003 Temperature Monitoring Locations

5. 5 2003 Temperature Logger Data Field data confirmed suspected large lateral differences… Site 5 a & b – Red Wolf Bridge

6. 6 Sites 6 & 7 – Confluence 2003 Temperature Logger Data Field data confirmed suspected large lateral differences…

7. 7 Site 8 a & b – Blue Bridge 2003 Temperature Logger Data Unexpected: cold water migrating upstream

8. 8 Mode 1: April 4, 2002 Upstream Snake Temperature: 7.4°C Discharge: 829 m3/s Clearwater Temperature: 5.8°C Discharge: 746 m3/s Temperature delta: 1.6°C S/C Discharge ratio: 1.1 (~equal Q and T)

9. 9 Mode 2: May 23, 2003 Upstream Snake Temperature: 13.5°C Discharge: 1697 m3/s Clearwater Temperature: 10.0°C Discharge: 1215 m3/s Temperature delta: 3.5°C S/C Discharge ratio: 1.4 (high Q ratio, temp ~equal)

10. 10 Mode 3: July 21, 2002 Upstream Snake Temperature: 22.7°C Discharge: 446 m3/s Clearwater Temperature: 13.4°C Discharge: 479 m3/s Temperature delta: 9.3°C S/C Discharge ratio: 0.9 (large temp delta, Q ~equal)

11. 11 Typical pattern… Clearwater subducts under the Snake River. Satellite Image 7/21/2002 Temp delta = 9.3°C Density Driven Flow Colder Clearwater R flowed upstream along bottom of the Snake R. Upstream motion halted when a balance of momentum was reached (density/gravity versus shear). 18 Degree Isotherm20 Degree Isotherm 14 Degree Isotherm 20 18 °C 16 14 20 18 °C 16 14 20 18 °C 16 14

12. 12 Mode 4: July 30, 2003 Upstream Snake Temperature: 23.3°C Discharge: 473 m3/s Clearwater Temperature: 11.3°C Discharge: 386 m3/s Temperature delta: 11°C S/C Discharge ratio: 1.2 (Larger Snake, large T delta) Mode 5 would be large Clwtr, but not observed

13. 13SummarySummary Mode 1 – equal Q & T Mode 4 – larger S Q, large ΔTMode 2 – larger S Q, equal T Mode 3 – equal Q, large ΔT

14. 14 3-D CFD Model of the Confluence Applying Flow-3D, a commercial software package because: Large user base Previously tested/verified by PNNL & others. Solves the 3-D RANS equations using a 2 nd order finite-volume method. Several turbulence models available; currently using RNG. Physical domain is decomposed into 4 Cartesian blocks, which are composed of variable sized hexahedral cells. ~2M total cells used here.

15. 15 equal Q & large ΔT (Mode 3) CFD Results

16. 16 equal Q & large ΔT (Mode 3) CFD Results

17. 17 SummarySummary Circulation dynamics are determined by: Ratio of discharge Density differences Processes have been: Observed with temperature loggers Observed with ADCP (not shown) Observed with IR & visible band satellite images Simulated with 3-D CFD model Momentum balance (mode) can now be predicted.

18. 18 Where are we going with this research? Response of anadromous salmonids and other aquatic species is being studied. Patterns in the confluence can be produced by managing timing, quantity, and quality of upstream releases from DWK reservoir (Clearwater). AcknowledgmentsAcknowledgments Bonneville Power Administration (Project 2002-027) U.S. Dept. of Energy, National Nuclear Security Administration, MTI satellite imagery