hydrologic indices

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?