Page 27 - Beaumont Basin Watermaster

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

S c = Specific Capacity (gpm/ft)
S = Storativity (assumed to be equal to the value from the nearest well
with a storativity estimate)
t = Time (days)

Transmissivity estimates based on specific capacity data have a wide range in values but
generally show regions of similar values (see Appendix C). Transmissivity estimates from
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2
specific capacity data range from less than 100 ft /day to approximately 19,000 ft /day with an
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average of 5,000 ft /day. The highest transmissivity values were observed at wells located in the
central Beaumont Basin. Lower transmissivity values were observed in the southern Beaumont
Basin near Interstate 10, in the Calimesa area and in the Banning area.

3.3.2.3 Hydraulic Conductivity

Hydraulic conductivity is a coefficient of permeability that describes the rate that water flows
through a permeable medium (Fetter, 1994). Hydraulic conductivity is related to transmissivity
through the following relationship:

Where:

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K = Hydraulic Conductivity (gpd/ft );
T = Transmissivity (gpd/ft); and
b = Aquifer thickness (ft)

As many of the wells in the Beaumont Basin are perforated across both the Upper Aquifer and
Lower Aquifer, it was necessary to apportion the hydraulic conductivity in accordance with the
hydrologic characteristics of the individual aquifers. This was conducted based on flowmeter
test results in BCVWD Wells 23, 24, 25 and 26 (see Table 1). Flowmeter tests in these wells
show that the flow contribution of the Upper Aquifer is 81 to 96 percent of the total flow to the
wells. The average flow contribution of the Upper Aquifer is 88 percent of the total flow.

Hydraulic conductivities for the combined aquifer thickness was first estimated from the
transmissivities derived from pumping tests. Aquifer thickness was assumed to be the perforated

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