SacEFT: Bank swallow model

1. Sacramento River Ecological Flows Tool Refinements Workshop Expanding & Communicating Ecological Considerations Used to Evaluate Water Management Alternatives October 7, 2008 Katherine Wieckowski SacEFT: Bank swallow model

2. The system context: multi-year resolution • Multivariate – species, life history stages, units • Need to integrate, aggregate and compare with asimple common palette • There must be credible models under the hood • Experts may need to drill down to years, days, locations

3. The system context: annual resolution • Rules for assigning colour breaks differ for daily and annual scales and are sometimes complicated WY1974 – wet year WY1977 – critically dry year

4. The system context: daily resolution • When present, daily color(R/Y/G)depends on distribution of historical daily results across all locations • All examples show a Good and Poor year

5. Habitat requirements Nesting habitat: • Nests burrows built in steeply sloped banks in friable soils • Immediately adjacent to still or running water • Banks renewed every few years by erosive processes

6. Bank swallow (BSW) indicators • Two indicator models chosen through 2005 workshop • Models share common structure but different parameters • Models are habitat-based, not population-based*

8. Selected functionalrelationships

9. BSW indicators BSW1 – Length of newly eroded banks with suitable soil texture (m) BSW2 – Indicator of bank sloughing (i.e., collapse) during nesting (Red/Yellow/Green hazard zones)

10. BSW indicators: temporal context Generalized phenology of bank swallow life history stages for birds breed in the Sacramento Valley, California Stillwater Sciences (2007)

11. Representative hydrograph from pre-Shasta period relative to bank swallow life history stages. Stillwater Sciences (2007)

12. BSW indicators: spatial context Keswick RM 301 Red Bluff RM 243 Colusa RM 143 light green – area captured by BSW1 (area most relevant for bank swallow biology) dark green – areas captured by BSW2

13. BSW indicators: spatial context River segment 2 RM201 RM185

14. BSW1– Length of newly eroded bank • L depends on meander migration rate (W) and area of floodplain reworked (A) • Meander migration model solves for WandA • L calculated annually for each modeled bend • Scoring of annual results is based on terciles of total length taken from historical run with no bank revetment • Lis insensitive to flow

15. 0 when (L < 13m) wbwhen (13m≤ L ≤ 20m) 1 when (L ≥ 20m) BSW1 – Length of newly eroded bank 1. Calculate L for each bend (b): 2. Weight or each bend (b): 3. Weighted useable Lb for each segment (l): 4. Calculate BSW1 for the river :

16. BSW1- Length of newly eroded bank

17. BSW1: Why insensitive to flow? • Low inter-annual variability in W • Scale mismatch between meander migration model and length scale used for weighting. • Narrow range of variation in terciles generated from historical data • L doesn’t account well for depth of bank erosion Stillwater Sciences (2007)

18. BSW2 – Peak flow during nesting • Calculated daily by location (3 locations) using flow (Q) • Based on flow thresholds (20 kCFS and 50 kCFS) • Timing of flows effects impact • Scoring of daily and annual results is heuristic • Somewhat insensitive to flow

19. 1 when (Q < 20kCFS) BSW2=when (20kCFS≤ Q ≤ 50kCFS) 0 when (Q ≥ 50kCFS) BSW2 – Peak flow during nesting 1. Calculate BSW2 for each location: • If 2 or more locations are good, BSW2R is assigned good • Lower ratings are assigned as poorer site performance is observed (e.g., if 2 or more locations are bad, BSW2R is assigned bad) 2. Calculate annual BSW2R for the river

20. 1974 – wet year 1977 – critically dry year BSW2 BSW2