Review of Findings of WaterFALL Ecoflow Metrics as Compared to the Gage Metrics

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WaterFALL Metrics across NC
Michele C. Eddy
2/19/13

NC Ecoflow SAB
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Model Comparison Workshop
Organized by USFS
–Grant from Southeast Climate Science Center
–Working with USGS
195 sites over 8 states
“Unregulated” flows
5 – 17,200 mi2 drainage area (mean 560 mi2)
Participated by providing WaterFALL results from 24
gages from western NC to northern GA
Results show WaterFALL has similar performance to
other models (9 applications in total) in terms of model
efficiency and bias in monthly and annual metrics
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WaterFALL Ecoflow Metrics in 6 Clicks
55 sites across the state
30-year POR
9 to 6,223 sq km (3.5 to 2,400 sq mi)
42% of gages were considered “reference” gages by USGS GAGES
II assessment
53% of locations were calibrated against USGS observations
Sites cover all McManamay classifications
Metrics:
–10th percentile: extreme low flows
–25th percentile: low flows
–50th percentile: average flows
–75th percentile: high flows
–90th percentile: very high flows
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January Extreme High Flows
Close up for smaller streams:
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March Low Flows
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July Extreme Low Flows
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Fall / Winter
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Summary
Largest variation is not by percentile but by month
–Most variation in fall (measured by relative percent difference,
RPD): September, October, and November
–Always a couple outliers in each percentile in each month
Some tendency to overestimate Median to Extreme High
flows in September through November yet…..
Across the 51 sites the median RPD between the gage
and model is <25% for all months and all percentiles
except:
–Median to Extreme High flows in October (<30%)
–Extreme Low to Median flows in November (<30%)
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ModelObs
ModelObsRPDNote: