Hydrologic Indices
Yuba River Development ProjectFERC Project 2246 Relicensing
Thursday, April 11, 2013
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Hydrologic Indices
Introduction Hydrologic index usage Existing indices in the Yuba River watershed Unimpaired Yuba River flow at Smartsville Comparison of indices Comparison of indices and Middle Yuba River flow Comparison of year-type classifications
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Yuba River Watershed
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Hydrologic Index Usage
Hydrologic Indices have two purposes: Characterize hydrology Define year-type classifications
Characterizing hydrology is critical to ensure accurate representation of a natural process
Year-type classifications are a statistical exercise to make sure “bins” capture correct flow ranges
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Existing Indices in Yuba River Watershed
Existing YCWA FERC License (4 WY) Based on annual unimpaired flow at Smartsville Year-types defined by percentage of 50-year average unimpaired flow
Yuba River Index (5 WY) Part of RD-1644, no current application for determining flows Based on weighted unimpaired flow at Smartsville
0.2*(prev index) + 0.3*(Oct-Mar) + 0.5*(Apr-Jul) North Yuba Index (6 WY)
Part of Yuba River Accord Based on end-of-Sept. New Bullards Bar storage + annual inflow
YB/DS Index (6 WY) Part of proposed license conditions Based on annual unimpaired flow at Smartsville
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Annual Unimpaired Yuba River Flow at Smartsville
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Annual Unimpaired Yuba River Flow at Smartsville
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Selected Comparisons of Existing Indices
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Selected Comparisons of Existing Indices
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Comparisons of Existing Indices
Three primary indices generally characterize hydrology similarly.
Slight differences due to variations in approach YRI emphasizes April-July runoff, so years like WY 2013
are represented as drier than in YB/DS NYI includes storage, so transitions from dry to wet are
represented as drier than in YB/DS (and inverse)
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Existing Indices vs. Middle Yuba River Flow
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Existing Indices vs. Middle Yuba River Flow
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Existing Indices vs. Middle Yuba River Flow
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Existing Indices vs. Middle Yuba River Flow
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Existing Indices vs Middle Yuba River Flow
Existing indices do a good job of representing annual hydrology of the Middle Yuba River
Monthly variability in Middle Yuba River flow is not well represented
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Comparison of Year-Type Classifications
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Comparison of Year-Type Classifications
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Comparison of Year-Type Classifications
Index Schedule 1/ Wet
Schedule 2/ Above Normal
Schedule 3/ Below Normal
Schedule 4/ Dry
Schedule 5/ Critical
Schedule 6 (7)/ Extremely
Critical (Conference)
North Yuba Index 22 7 5 3 2 0 (1)
Yuba River Index 16 6 6 4 9 -
YB/DS Index 10 13 5 9 3 1
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Comparison of Year-Type Classifications
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Year-Type Distribution
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Year-Type Distribution
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Year-Type Distribution
Yuba River Development Project (YRDP) – FERC Project 2246 Relicensing
Where do we go from here?