WAI

Here are the coordinates for our beach site. We sample 000224 “Pokai Bay” approximately once a week, the others are sampled less frequently.

Station NO

Location Name Latitude Longitude 

Waianae Beach Shoreline

21.441619 -158.191003  000315

Waianae Kai

21.446675  -158.190842. 000224

Pokai Bay

21.442669 -158.189447. 000183

 List of cesspools here in Hawai'i

That important observation of the glossy moving water is because fresh water and salt water weigh differently and allows one to float above the other. This is a great thing to teach the community to kilo about :) Mahalo for sharing the 'ike kupuna. I'm here for it!

From a physics standpoint, tides are caused by the moon orbiting around the earth. A tide happens because any part of the earth that is closest to the moon is getting pulled on by its gravitational field, which includes all the water and land. We see the most drastic effects of the tides in the waters since they are the more fluid as compared to how hard the land is. Your question of whether the water-table is affected by the tides is that - yes it is! 

That is a great observation about the glossy sheet of outflowing brackish water at low tide. The lower salinity causes groundwater (gw) to float on top of seawater and also have a different refraction of light.

Submarine groundwater discharge, as we call groundwater outflow at the coastal ocean, is driven by the head (=water level) difference between the gw in the aquifer and the ocean. Since gw level will be equal to or higher than mean ocean level the more water is recharged to the aquifer the higher the gw level will be resulting in larger coastal groundwater outflow. Tides however play a gatekeeper -at high tide that water level difference is smaller so groundwater outflow slows and often even stops or reverses letting seawater intruding into the aquifer. At low tide the water level difference increases allowing groundwater and intruded seawater to rush out again. That is why we see many coastal spring slow, stop or get saltier during high tide.

Waves and swell may produce a similar effect, forcing more seawater into the coastal aquifer, slowing down gw discharge.

We always sample at low tide when we look for terrestrial gw signatures for 2 reasons 1) groundwater outflow is the strongest and we have the highest chance of capturing it, and  2) whatever discharges gets diluted less because the amount of ocean water present at the beach is lower at low tide than at high tide.

NOAA's Center for Operational Oceanographic Products and Services is the office responsible for the measurement, analysis, and prediction of tides, tidal currents, and related oceanographic phenomena for the U.S. coastline.

Unfortunately, I doubt that we have information which is detailed enough to answer your questions.

There are only 2 operating stations on O'ahu, Hawai'i <map of operating stations> which provide continuous monitoring of tidal conditions.- 1612480 Mokuoloe, HI- 1612340 Honolulu, HI
There are no operating stations which monitor currents in this area.

There are a few historical stations, which observed data for a short period of time (a couple months) as part of a survey or other past project.  But none of these stations are in the specific area you are interested in.  <Map of historical stations>
There is a tide prediction station at 1612482 Waianae, HI.However, this will not provide information about currents in the area. 
We have no operational models of tides or currents in this area.

Have you tried contacting the University of Hawai'i, Oceanography Department?This is a very active Oceanography Department; and might have better information for this area.