Notes from DGAS Model Core Team Meeting, September 12, 1996

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1. Interim Report. Chris Pinney announced that the Walla Walla 30 % Work Review Report will be written by December. Contributors should write up a brief status report. The interim report is scheduled to be printed by Feb/Mar of next year.

2. Dissolved Gas Field Sampling. Joe Carroll reported on the 1996 field sampling studies. This year automated remote equipment was used, instead of boats, to obtain gas levels at lateral and longitudinal cross-sections in the river. LMN,IHR,MCN,TDA,BON pools and the tidal pool below BON were looked looked at for varying lengths of time, the longest being 30 days, to capture the 2-D spatial patterns over time. The monitoring started April 20 in LMN pool. Near field studies as well as the reservoir sampling were done. In the Near field studies instruments were concentrated in the navigation channel and in the first 1200 feet of the tailrace. The "tidal pool" reach below Bonneville was about a 25 mile stretch below Bonneville during the first sampling, and about a 100 mile strech during the second sampling. 4 pools: MCN,TDA,BON and the Tidal Pool were sampled twice, and the other two IHR and LMN were sampled once. The near field study at IHR was also done twice.

The 1996 data is available at an Army Corps ftp site. George Kalli is the data contact at (503)326-6184. ADCP velocity data will also be available. Lateral gradients were present in the river velocities.

3. Near Field Studies. Mike Schneider reported on the near field studies completed. The goal of these studies was to determine the near field dynamics to predict the "exit" level of gas in the tailrace. At IHR 2-hour spill patterns were used with 40-60 kcfs spill and about 60 kcfs generation water. Schneider commented that the "gas plateau" noticed in previous spill tests at IHR was still present at about 50-60 kcfs. 2 spill patterns were tested including the fish passage pattern. 25 kcfs spill at IHR helps keep the river at 120% regardless of the amount of gas coming in. LMN was chosen as an example of a deflector project. The dam operated at 14-25 kcfs spill with 7-50 kcfs generation water. LMN had significantly different levels of gas and gas contributions when using the adult versus juvenile spill patterns. In TDA pool monitors were placed at 100, 200,300,450, and 1000 ft. The tailwater monitor seemed to be a good representative of gas levels in the TDA pool. Look for summary of the spill test data by November. This information is needed to plan next years tests and operations. The Fish Passage Plan is going out in January.

4. Dissipation Rates. When asked if his gas transport model would include wind dependence in the dissipation rate, Marshall Richmond replied that the dissipation coefficient would ideally be wind dependent but currently is not. Joe Carroll commented that "Wind Dance" is a good source of archived wind data in the Columbia Gorge, up to Arlington. Tom Miller is a source of information about dissipation rates in the Snake River.

5. Transport Model. Marshall Richmond gave an update on PNL's Transport/Bathymetry model. This model now includes bathymetry data from Lewiston to Portland, and up to PRD on the mid-Columbia. There is a limited amount of info included on the river below Portland. Information includes detailed ARC info, GIS System data. River information is available as (x,y,z) points, but also as cross section files. Lance Vail reported on some of the numerical modelling for the hydro model. This will include evaluating velocities on a 3-D grid of the river. The tailrace will include more fine detail than the rest of the reservoir.

6. Gas Mortality Model. For the mortality model, Larry Fidler has created code for a computer model of LMN and IHR. This model includes 1-dim flow, quasi 2-D mixing, and a dynamic bubble trauma function. The dynamic DGS/GBT mortality model will have the following components:

  1. growth of spherical bubbles
  2. growth of tubular bubbles
  3. initiation of mortality
  4. mortality rate function.
All 4 GBT mortality stages will be integrated along river TDG exposure paths to yield cumulative mortality.

7. CRiSP Model. Jim Anderson explained the system approach of CRiSP and reported its prediction successes for 1996, using NMFS preliminary 1996 PIT tag survival data for validation. The NMFS preliminary results showed a 56% survival from LGR dam to the JDA collection sight, while CRiSP had predicted a 55% survival. Pam Shaw presented the intended changes for CRiSP 1.6 to incorporate a better gas model. These changes would include representing both the spill and the turbine flows. Gas would be exchanged between these flows as the water moves downstream and gas would also be dissipated. TDG monitoring data, previous years' transect data, and this year's field sample studies will be used to calibrate and validate the gas models. CRiSP 1.6 will also be incorporating more river temperature information, particularly in the headwaters.

8. Some general comments. Some of the hydroecousic studies done by NBS are collecting water quality data. Lower Monumental had a degassing influence last year, however this year it seems to be gassing the river. The NMFS/FPC Dissolved Gas Meeting will be on Oct 15th in Lacy, WA. PATH is advocating a 70% system survival.