BUREAU OF GEOLOGY


        T     =     transmissivity

        S     =     storeage coefficient

        r     =     period of fluctuation


      The time required for a given oceanic tidal fluctuation to travel through an artesian aquifer from the shoreline to an inland well (Ferris, 1962, p. 134, equation 67) can be written

                               t1      x. T                              (5)
                                       2    rrT


where   t1    =     the time lag at distance x from the shoreline.


                         HYDRAULIC DIFFUSIVITY

      Hydraulic diffusivity is defined as the conductivity of the aquifer when the unit volume of water moving is that involved in changing the head a unit amount in a unit volume of aquifer (Lohman, 1972, p. 8). As stated -earlier it is essentially the ratio of transmissivity (T) to the storage coefficient (S) or the ratio of hydraulic conductivity (K) to specific storage (Ss).

                      Hydraulic diffusivity = T% = K/S s                 (6)

      Equations 4 and 5, the stage-ratio and time-lag equations of Ferris, were rearranged and solved for diffusivity (T/S):

                 T/S = K      = x2      7r                               (7)
                         S s    r    (In h0)2
                                        w


                 T/S   K       -x2     T                                 (8)
                           s    4 7r   t2

      The hydraulic diffusivity of the Boulder Zone was computed by a method using equations 7 and 8, trigonometric equations suggested by Cooper to separate ocean-tide and earth-tide components of the water-level fluctuations in