THROUGH-DELTA FACILITY WHITE STURGEON PASSAGE LADDER STUDY

Project Description:

The University of California, Davis (UCD) and the California Department of Water Resources (DWR), including biologists and engineers from both institutions, completed a three-year research study to determine the feasibility of a sturgeon ladder passage and to evaluate its use with the Delta Cross Channel (DCC), or a Through-Delta Facility (TDF).  This objective had four parts:

  1. Investigate the effects on sturgeon behavior of a range of flow control structures (including vertical slot, horizontal ramps, and orifices) that may be used as components of sturgeon passage systems
  2. Investigate hydraulic factors that likely affect successful passage: effects of velocity,
    turbulence, and flow rate
  3. Determine the flow control baffle design that will provide the hydraulic requirements
    allowing passage of adult sturgeon
  4. Test a prototype mid-ladder fish passage section (“random midsection”) as a component
    of a potential TDF fish passage structure and collect information for design of entrance
    and exit sections

In Year 1, experiments investigated if adult white sturgeon could negotiate through the slots of vertical baffles and over horizontal barriers with and without ramps. Two configuration of baffles were tested, at three different velocities. Fish swimming performance around the barriers was evaluated as either successful (fish passed the barrier), or unsuccessful (fish did not pass the barrier).

Schematic of flume and flow direction (top) and cross section of flume (bottom).

Plan views of Year 1 flume baffle configurations: dual Vertical-Vertical (VV) baffle (top), Horizontal-Vertical (HV) baffle (bottom).

Year1Config

Photo of Year 1 VV configuration

Velocity Percentage passing both barriers (VV configuration) Percentage passing both barriers (HV configuration)
Slow 29% 22%
Medium 61% 11%
Fast 55% 11%

In Year 2, experiments investigated sturgeon ability to negotiate a circular orifice passage, and 20-foot sloped ramp (4% and 8%).  Successful passage was defined as moving at least one body length upstream of the circular orifice. Successful passage of the sloped ramp was defined as one body length past x=35-feet, with the peak of the slope at x=40-feet in the flume.

Year2Config

Cross-sectional view of the orifice used in Year 2 experiments.

YEar2_TDF_ramp

Sloped ramp tested at 4% and 8% slope during Year 2 experiments.

Velocities measured along the length of the flume for the orifice, 4% slope and 8% slope in Year 2 experiments.

Velocities measured along the length of the flume for the orifice, 4% slope and 8% slope in Year 2 experiments.

Velocity % Successful Passage of Orifice % Successful Passage of 4% Slope Ramp % Successful Passage of 4% Slope Ramp
Slow 14 27 14
Medium 0 71 29
Fast 0 29 0

In Year 3, experiments investigated sturgeon ability to pass a system of baffles set in the flume with 4% bed slope. According to the Year 1 and 2 experimental results, baffles were designed to dissipate energy, and provide sturgeon a clear path to the slot opening with flow providing guidance. The main functions of the passage were to dissipate flow energy by contracting the flow, straightening the flow through the face of the baffle to minimize turbulence and then expand the flow for additional energy dissipation. The methods used to manage the flow using contraction, straightening and expansion (CSE) will reference this sturgeon passage design as a CSE Sturgeon Passage Ladder. Two hydraulic scenarios were tested, experimental condition – 1 (36-inch tailwater depth) and experimental condition – 2 (32-inch tailwater depth).

Year3_TDF_PlanView

Plan view (top) of random section of Year 3 CSE sturgeon passage baffles, and an upstream cross-section view of a pair of baffles (bottom).

Three-D_Year3_TDF

Rendered 3-D view of Year 3 configuration, 4% bed slope, five baffles and 12-foot pool length.

TDF_Year3_BafflePassage

Year 3 passage success for experimental condition -1 (36-inch tailwater depth) and experimental condition – 2 (32-inch tailwater depth).