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4. High Precipitation and High Wind Event - Low Lunar Tide (10/26/2018 to 11/05/2018)
a. Description
This period was characterized by a wind and rain event during a low lunar tide. The primary event occurred on 10/27/2018 with approximately 1.1 inches of precipitation and a 26-knot maximum wind speed. Because this occurred during relatively low tides, the spiking of the NOAA Tide Gage water level suggests that it was a response to the forcing event itself and not related to tidal cycles.
Note: GWW31 is not included in this period. Data collection was discontinued in this well at the end of water year 2017.
b. Water Level Response
Groundwater and seawater levels spiked above land surface in both the near-shore and inland wells and then rapidly returned to base levels.
c. Specific Conductance Response
The specific conductance level in GWW32 increased and decreased rapidly with the spike in the tide and groundwater levels. The specific conductance level in GWW33 also appeared to initially spike; however, after the rapid decrease the specific conductance level rapidly increased and remained elevated for the duration of the analysis period. Specific conductance levels in GWW34 rose and fell rapidly with the water level spike.
5. High Precipitation and High Wind Event - Low Lunar Tide (12/20/2018 to 12/30/2018)
a. Description
This period was characterized two rain events and frequent high winds during a low lunar tide. The first event occurred on 12/21/2018 with approximately 1.5 inches of precipitation and a 23-knot maximum wind speed. This event was followed by a high wind event on 12/22/2018 exceeding 30 knots and a high wind event of 22 knots from 12/24/2018 to 12/25/2018. The second event occurred on 12/28/2018 with approximately 0.5 inches of precipitation and a 22-knot maximum wind speed. This event was also followed by a high wind event on 12/30/2018 with a maximum wind speed of 22 knots. Sea levels were elevated during this period with sustained diurnal tides.
b. Water Level Response
Water levels in the near-shore wells experienced rapid increases during the first precipitation event. Diurnal fluctuations corresponding to the tides were also observed. Water levels in GWW32 peaked above land surface with diurnal tides during the high winds from 12/21/2018 to 12/23/2018. Water levels in GWW33 and GWW34 did not exceed land surface elevations; diurnal fluctuations were damped when compared to GWW32 due to the greater distance from the shoreline. Sea levels peaked slightly above land surface elevations of GWW33 and GWW34 when wind speeds were at a maximum on 12/22/2018 and 12/23/2018.
Water levels in GWW30 increased slightly during the first precipitation and wind event on 12/21/2018 but did not exceed the land surface elevation. Slight increases were also observed during the wind event on 12/24/2018 and the second precipitation event on 12/29/2018.
c. Specific Conductance Response
Specific conductance levels in GWW32 and GWW33 increased significantly in response to the first precipitation event and remained elevated for most of the analysis period. The specific conductance in GWW32 also increased in response to elevated wind speeds on 12/24/2018.
Over the 10-day period GWW33 experienced a gradual but significant increase of 20,000 µS/cm and followed by a gradual decrease to the base level. This initial increase/decrease was slightly shifted from the diurnal tide. GWW34 experienced a slight decrease in specific conductance levels during the first precipitation event and remained depressed for the full analysis period.
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Last updated: December 5, 2022