Page 44 - Beaumont Basin Watermaster

Beaumont Basin Watermaster
2013 Reevaluation of the Beaumont Basin Safe Yield 3-Apr-15

6.0 Analysis of Safe Yield

The Safe Yield of the Beaumont Basin is a function of the overall water balance of the
adjudicated area. As described in Section 1.3, the Safe Yield can be expressed using the
following equation:

Safe Yield = S + O p - I ar (4)

where:
S = Change in Groundwater Storage

O p= Outflow from Groundwater Pumping
I ar = Inflow from Artificial Recharge of Supplemental Water

This relationship is valid if the following conditions are met:

1. The Safe Yield incorporates a hydrology that is representative of a relatively long period
of record that includes multiple wet and dry hydrologic cycles.
2. The land use conditions are representative of the time period.
3. Pumping and recharge within the basin does not result in adverse impacts.

6.1 Safe Yield Based on Historical Land Use and Basin Management

Annualized Safe Yield for the historical period between 1972 and 2012 (40 years) was evaluated
using the water balance developed from the calibrated groundwater flow model (see Table 7).
The water balance and annualized Safe Yield shown in Table 7 is specific to the adjudicated
Beaumont Basin area. As shown, the annualized Safe Yield ranged from approximately 3,500 to
8,100 acre-ft/yr with a 40-yr average Safe Yield of 5,424 acre-ft/yr. The cumulative change in
groundwater storage over this time period was approximately -124,000 acre-ft. The greatest
depletion in groundwater storage occurred between 2000 and 2010.

Year to year changes in the historical Safe Yield of the Beaumont Basin between 1972 and 2000
were influenced primarily by changes in groundwater pumping within the basin (see Figure 38).
Between 1972 and approximately 2000, years of increased groundwater pumping within the

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