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Sacramento Model Calibration

• Goals– Unbiased reproduction of historical conditions– Parameters that cause model components to mimic

the hydrologic processes they were designed to represent

– Ability to extrapolate beyond conditions encountered in the historical record

• Strategy– Must account for the physics of the model and how

each portion of the hydrograph was intended to be modeled

– Must understand the structure of the model

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Conceptual Representation of SAC-SMA

INTERFLOWSURFACERUNOFF

INFILTRATIONTENSION

TENSION TENSION

PERCOLATION

LOWERZONE

UPPERZONE

PRIMARYFREE

SUPPLE-MENTAL

FREE

RESERVED RESERVED

FREE

EVAPOTRANSPIRATION

BASEFLOW

SUBSURFACEOUTFLOW

DIRECTRUNOFF

Precipitation

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(each t)

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Sacramento Model - Percolation

LZFPMLZFSMLZTWM

LZFPCLZFSCLZTWCLZDEFR

0.1

Function of two forces:

• Lower Zone Dryness (Capillary Suction Force)

Lower Zone Deficiency Ratio (LZDEFR)

• Upper Zone Free Water Wetness (Gravity Force)

UZFWM

UZFWC

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Why nopercolationhere?

When ispercolation at the max rate?

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2

LZTWMUZTWMADIMC

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Direct RO = UZTW Excess Fracdir ADIMP

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LZTWC

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Dry areas: evapotranspiration assumes ‘connection’ between upper and lower zones