REPORT OF INVESTIGATIONS No. 38 21
Proposed
rIntrocoostol
-Wo terwoy
Water-table otsa aquifer 100 fee
W-20 '
E . . . . . . . . . . . .
SFitrst artesion ofsalt w- aquifer
W -60 ..... .. .':CanIi i ng. ::::! b e.d
F-80 Second artesian aquifer e tf .2
o F ,:,,_ A AF-,- o+:.+I
-100 / /u Sail woter
Postuloted direction of movement of salt water
cased( I
uncased
Well bore
Figure 7. Generalized cross section near Venice well field at site of proposed
waterway showing postulated direction of salt-water movement.
SALT-WATER WEDGE
The area of the interface between the salt-water wedge and the upper confining beds can be determined easily from the width of the base of the salt-water wedge. This width was estimated from the relationship between salt water and fresh water and from the theoretical position of the water table near the proposed waterway.
The relationship between salt water and fresh water under static conditions may be expressed as follows:
t
h =
g -1
where h equals the depth of fresh water, in feet below sea level; t equals the height of the water table, in feet above sea level; g equals the specific gravity of sea water, and 1 is the specific gravity of fresh water. The relationship is generally referred to as the Ghyben-Herzberg principle, after the names of the two men who first described it.