Currents and related problems at Metropolitan Beach, Lake St. Clair / John C. Ayers.

Observed Alongshore Currents
In October 1962 drogues were used to check the validity of
alongshore currents being recorded by the current indicator
installed at the west end of the bathing beach. These runs,
plus visual observations of current direction at about weekly
intervals when the recording station was serviced, showed that
the current indicator was correctly indicating current direction.
The drogue studies also showed that the alongshore current
moves in a wide belt, and that along the Beach property there
were no local eddies. On the basis of these studies it was
determined that dominant currents recorded by the current
indicator could be used in verification of the models.
Alongshore Currents in Relation to Wind
In Figure 3 are presented the directions of alongshore
currents recorded under the eight wind directions. The wind
(direction from) is indicated above each current frequency rose.
Arrow-heads on the rays of the roses indicate that currents are
named by the direction toward which they move.
Velocity of alongshore currents is less important than
current direction in the particular practical problems underlying this study. In general the stronger of the alongshore
currents were the most consistent of the currents; weaker currents
involved greater percentages of "calms" when no current was recorded. Calms are a function of sheltering by the land while
current velocities are, at least in part, a function of the
length of open water across which the wind blows. Table 1 gives
the observed percentages of calms (no discernable current) in

the alongshore water as recorded by the current indicator.
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