Tide Table
Explanatory Note and Monthly Tide Tables
The values provided below were supplied by the Hydrographic Institute.
The harmonic analysis was performed based on tidal observations from 1975.
The tide gauge is installed at the Port of Leixões at the following coordinates:
Latitude 41º 11'.1N
Longitude 8º 42'.2W
The values indicated in the table may differ significantly from the actual values due to variations in the mean sea level, mainly due to atmospheric conditions.
These differences usually do not exceed 0.3 to 0.4 meters for heights and 10 to 15 minutes for times, but under exceptional conditions, they can reach substantially higher values.
Monthly Tide Tables
Tide Concordance for the Douro River Bar
The tide concordance for the Douro River Bar is obtained through a time correction (Δt = +16 minutes) and an amplitude ratio (r = 0.93).
Example:
January 2, 2021
|
Hour
|
|
|---|---|
|
Hora da preia-mar em Leixões |
00h22 |
|
Correcção do tempo |
+00h16m |
|
Hora de preia-mar no Douro |
00h38m |
|
Tide height
|
|
|---|---|
|
Altura da preia-mar em Leixões |
2,90 m |
|
Altura do nível médio |
-2,00m |
|
|
0,90 m |
|
Redução da Amplitude |
x 0,93 |
|
Elevação da maré na barra do Douro |
0,84 m |
|
Altura do nível médio |
+2,00m |
|
Altura da preia-mar na barra do Douro |
2,84 m |
Conditions for the use of tidal information
© Copyright Navy, Hydrographic Institute, 2022. Published with authorization n.º 17/2023 from the Hydrographic Institute, Navy.
This publication does not replace the official publications of the Hydrographic Institute, which disclaims any responsibility arising from the use of the transcribed tidal elements.
Users are advised that the tidal predictions indicated are referred to a time zone that may not coincide with the time zone corresponding to the legal time.
Given that the Hydrographic Zero Plane (ZH) was fixed in relation to average levels adopted several decades ago, there is currently a systematic difference of about +10 centimeters between the observed water levels and the predicted tide heights.
For more information, please refer to www.hidrografico.pt