SAUDI TIDE TABLES

2020

(1441-1442 H)

ARABIAN GULF

VOLUME – II

PUBLISHED BY GENERAL DIRECTORATE OF HYDROGRAPHY,

GENERAL COMMISSION FOR SURVEY,

SAUDI ARABIA

©GCS Copyright 2019

PREFACE

The tide tables show advance prediction of tides for a particular location. These tables

show the daily times and heights of predicted high and low water. The Saudi Tide

Tables contain both daily and hourly tide predictions for the Red Sea and Gulf of Aqaba

(Volume-I) and Arabian Gulf (Volume-II). The source of tide predictions, general

characteristics of tides in the Arabian Gulf, non-tidal effects, and other relevant

information are given in the following sections.

Purpose of the Saudi Tide Tables

This Volume (II) of Saudi Tide Tables contains comprehensive details of predicted tide

data for the Arabian Gulf and these tables are published annually by the General

Directorate of Hydrography, General Commission for Survey (GCS), Saudi Arabia.

GCS is mandated by the Government of Saudi Arabia for geodetic, topographic and

hydrographic surveys, production of maps/charts, establishment and development of

geographic information systems, geospatial data, etc., in the Kingdom of Saudi Arabia.

Time Zone for Tide Predictions

All the predictions in Part I to III are given in Local Time (GMT + 3 hours) but a negative

prefix is used for east of Greenwich. Hence, the Time Zone number to be subtracted

to convert the Local Time Zone to GMT.

Height Reference of Tide Predictions

All the predicted tidal heights are in meters and above the Lowest Astronomical Tide (LAT).

Reproduction of tidal data in local tables, almanacs and newspapers

All the information contained in these tables is protected by GCS copyright.

Permission to reproduce any information contained in these tables must be obtained

from GCS in advance.

Disclaimer

GCS makes no representation as to the fitness, quality or suitability of the tide

products or services supplied by any person other than GCS and no endorsement of,

connection of GCS with, such products or services, is to be inferred.

FEEDBACK

The predictions shown in these tables are for average meteorological conditions.

Especially, caution to be exercised while extracting predictions for the secondary

stations as the predictions for these stations are made using limited data (refer Table

III for details). Hence, the Users and Port Authorities are requested to keep GCS

informed of any significant changes or inaccuracies in the predicted tide tables and

give timely feedback on any observed variations.

General Directorate of Hydrography General Commission for Survey

Riyadh, Saudi Arabia

GCS CONTACT DETAILS

General Directorate of Hydrography General Commission for Survey Al-Olaya Road and Intersection with Abdul Malik Bin Marwan Road Opposite to Olaya Post Office PO Box No-87918, Riyadh, 11652 KSA. Telephone: +966 920000427; Fax: +966 1 4648909 Email: hydro@gcs.gov.sa ; Website: www.gcs.gov.sa

MAP OF TIDE PREDICTIONS AVAILABLE FOR ARABIAN GULF

The tide predictions given in this Volume-II are only for Arabian Gulf coastal regions of Saudi Arabia

INTRODUCTION

Tides in the Arabian Gulf

Tides are the rise and fall of sea levels caused by the combined effects of the

gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.

The tides are mainly classified into four categories. They are (i) semi-diurnal tides (two

high tides and two low tides each day); (ii) diurnal tides (one high tide and low tide

each day); (iii) diurnal-mixed tides (one uneven high tide and low tide each day); (iv)

semi-diurnal-mixed tides (two uneven high tides and low tides each day).

The tides in the Arabian Gulf exhibit semi-diurnal to mixed tides to diurnal tides. The

tidal ranges are meso-tidal in the Arabian Gulf. The tidal ranges are small in the

Arabian Gulf as the basin is connected to the Indian Ocean through a narrow entrance,

also its small basin dimensions restrict the direct action of tidal forces up to some

extent, but the direct action of the tidal forces still plays a significant role in the basin.

There are two Amphidrome systems in the Arabian Gulf, one in the northwestern part

and the other one in the southern part. Diurnal tides are experienced close to these

Amphidrome points and semi-diurnal tides at the anti-nodal points of these two

systems (located in the middle of the basin).

Meteorological and Seasonal Effects on Sea Level

The changes in the sea level due to the non-tidal effects in the Arabian Gulf are about

–20 to 35 cm. The possible drives of the non-tidal effects include strong local winds

and air pressure systems over the basin and external forcing from the Indian Ocean.

The tides in the Arabian Gulf are strongly influenced by seasonal cycles. The tidal levels

peak in June to September. The seasonal variations can add up to 20 cm in the Arabian

Gulf.

Seismic Waves/Tsunamis

Seismic waves or Tsunamis are long waves generated by sub-marine earthquakes,

landslides, volcanic eruptions or meteorite impacts in an open ocean. These long

waves can cause drastic changes in the sea level near the coastal regions and these

abrupt changes in the sea level can last for a few hours to days. The chances of abrupt

changes in the sea level due to the Tsunami are remote in the Arabian Gulf owning to

its shallow basin, which can dissipate the energy of Tsunami waves when they

approach the coasts. The Tsunami events in the adjacent Indian Ocean are also

unlikely to make any considerable impact as the energy generated by Tsunami waves

will be dissipated when they enter through the narrow connecting channels.

Tidal Streams, Currents and Slack Water

Tidal streams are horizontal movement of water that occur in the ocean in conjunction with a rise and fall in the sea level. Current is a general term used for the horizontal and vertical movement of water due to tides, winds, and density differences. The slack water is a particular phase of a tidal current when its velocity becomes nearly zero. The relation of the time of slack water to the tidal phases varies from place to place.

Method of Tide Predictions

The predictions given in these tables are based on the continuous observations of tides (refer Tables II&III) from GCS National Tide Gauge Network and Hydrographic Survey Projects. The Harmonic Analysis of tide data were carried out using the Tidal Analysis Software Kit 2015 (Windows Edition, Version 2.0.0) developed by the Marine Data Products Team at the UK National Oceanography Centre, and at many stations, over 100 tidal constituents were used for the predictions shown in these tables. The Highest Astronomical Tide (HAT) and Lowest Astronomical Tide (LAT) Levels are generated by scrutinizing an 18.6-year period of generated predictions in TASK Software.

INSTRUCTIONS FOR THE USE OF TABLES

The times and heights of daily high and low water tides are given in Part I&II of these tables. The times and heights of tides for every hour of the day are given in Part III of these tables. The occurrence of Spring and Neap phases of tides can be found by referring to the symbols for New/Full Moon and First/Third Quarter Phases (New Moon (), Full Moon () First Quarter () and Last Quarter ()). All the times mentioned in these tables are GMT + 3 hours and in 24-hour format. The tidal heights are in meters and above the Chart Datum (LAT) of the Station/Port concerned (refer Tables II&III).

Note-1: The Table-I gives definitions for tidal datums.

Table II - The Tidal Datums Derived for Primary Stations in the Stations in Arabian Gulf Stations

Primary Stations LAT

MLW

S

MLW

N

MSL

MH

WN

MH

WS

HA

T

Authority for Observations

/ Predictions

Year of Observations

Ras Abuqamis 0.0 0.68 0.96 1.14 1.33 1.61 2.67 GCS 2012-18(7.0 years)

Aloqair 0.0 0.17 0.23 0.33 0.42 0.49 0.71 GCS 2012-18(7.0 years)

Ras Tanura 0.0 0.32 0.73 1.13 1.50 1.91 2.32 GCS 2012-18(4.5 years)

Mardouma 0.0 0.50 0.75 0.99 1.23 1.48 2.03 GCS 2012-18(7.0 years)

Al Khafji 0.0 0.93 1.14 1.36 1.57 1.79 2.41 GCS 2012-18(6.3 years)

Note-2: The tidal datums shown in Table-II are in meters and above the Chart Datum (Lowest Astronomical Tide).

Table III - The Tidal Datums Derived for Secondary Stations in the Stations in Arabian Gulf Stations

Secondary Stations LAT

MLW

S

MLW

N

MSL

MH

WN

MH

WS

HA

T

Authority for Observations/ Predictions

Year of Observations

Salwa 0.0 0.08 0.23 0.43 0.64 0.79 1.05 GCS 2015-16(8.0 months)

Ras Quaryyah 0.0 0.19 0.24 0.29 0.37 0.42 0.67 GCS 2015-16(8.0 months)

Al Khubar 0.0 0.13 0.20 0.26 0.34 0.41 0.67 GCS 2015-16(6.8 months)

Shati Nisf Al Qamar 0.0 0.17 0.21 0.27 0.36 0.40 0.69 GCS 2015-16(1.8 months)

Table I - Tidal Datums

Highest Astronomical Tide (HAT)

The elevation of the highest predicted astronomical tide expected to occur at a specific tide station above the Lowest Astronomical Tide.

Mean High Water Spring (MHWS)

The average height of the high waters of Spring Tides above Lowest Astronomical Tide

Mean High Water Neap (MHWN)

The average height of the high waters of Neap Tides above Lowest Astronomical Tide.

Mean Sea Level (MSL)

The arithmetic mean of hourly heights observed above Lowest Astronomical Tide.

Mean Low Water Neap (MLWN)

The average height of the low waters of Neap Tides above Lowest Astronomical Tide

Mean Low Water Spring (MLWS) The average height of the low waters of Spring Tides above Lowest Astronomical Tide

Lowest Astronomical Tide (LAT) The elevation of the lowest astronomical predicted tide expected to occur at a specific tide station over the period of 18.6-year tidal cycle.

Table IV - Meters to Feet Conversion Table

Meters Feet Meters Feet Meters Feet Meters Feet Meters Feet Meters Feet Meters Feet Meters Feet

0.05 0.16 4.05 13.29 8.05 26.41 12.05 39.53 16.05 52.66 20.05 65.78 24.05 78.9 28.05 92.03

0.10 0.33 4.10 13.45 8.10 26.57 12.10 39.70 16.10 52.82 20.10 65.94 24.10 79.07 28.10 92.19

0.15 0.49 4.15 13.62 8.15 26.74 12.15 39.86 16.15 52.99 20.15 66.11 24.15 79.23 28.15 92.36

0.20 0.66 4.20 13.78 8.20 26.90 12.20 40.03 16.20 53.15 20.20 66.27 24.20 79.40 28.20 92.52

0.25 0.82 4.25 13.94 8.25 27.07 12.25 40.19 16.25 53.31 20.25 66.44 24.25 79.56 28.25 92.68

0.30 0.98 4.30 14.11 8.30 27.23 12.30 40.35 16.30 53.48 20.30 66.60 24.30 79.72 28.30 92.85

0.35 1.15 4.35 14.27 8.35 27.40 12.35 40.52 16.35 53.64 20.35 66.77 24.35 79.89 28.35 93.01

0.40 1.31 4.40 14.44 8.40 27.56 12.40 40.68 16.40 53.81 20.40 66.93 24.40 80.05 28.40 93.18

0.45 1.48 4.45 14.60 8.45 27.72 12.45 40.85 16.45 53.97 20.45 67.09 24.45 80.22 28.45 93.34

0.50 1.64 4.50 14.76 8.50 27.89 12.50 41.01 16.50 54.13 20.50 67.26 24.50 80.38 28.50 93.50

0.55 1.80 4.55 14.93 8.55 28.05 12.55 41.17 16.55 54.30 20.55 67.42 24.55 80.54 28.55 93.67

0.60 1.97 4.60 15.09 8.60 28.22 12.60 41.34 16.60 54.46 20.60 67.59 24.60 80.71 28.60 93.83

0.65 2.13 4.65 15.26 8.65 28.38 12.65 41.50 16.65 54.63 20.65 67.75 24.65 80.87 28.65 94.00

0.70 2.30 4.70 15.42 8.70 28.54 12.70 41.67 16.70 54.79 20.70 67.91 24.70 81.04 28.70 94.16

0.75 2.46 4.75 15.58 8.75 28.71 12.75 41.83 16.75 54.95 20.75 68.08 24.75 81.20 28.75 94.32

0.80 2.62 4.80 15.75 8.80 28.87 12.80 41.99 16.80 55.12 20.80 68.24 24.80 81.36 28.80 94.49

0.85 2.79 4.85 15.91 8.85 29.04 12.85 42.16 16.85 55.28 20.85 68.41 24.85 81.53 28.85 94.65

0.90 2.95 4.90 16.08 8.90 29.20 12.90 42.32 16.90 55.45 20.90 68.57 24.90 81.69 28.90 94.82

0.95 3.12 4.95 16.24 8.95 29.36 12.95 42.49 16.95 55.61 20.95 68.73 24.95 81.86 28.95 94.98

1.00 3.28 5.00 16.40 9.00 29.53 13.00 42.65 17.00 55.77 21.00 68.90 25.00 82.02 29.00 95.14

1.05 3.44 5.05 16.57 9.05 29.69 13.05 42.81 17.05 55.94 21.05 69.06 25.05 82.19 29.05 95.31

1.10 3.61 5.10 16.73 9.10 29.86 13.10 42.98 17.10 56.10 21.10 69.23 25.10 82.35 29.10 95.47

1.15 3.77 5.15 16.90 9.15 30.02 13.15 43.14 17.15 56.27 21.15 69.39 25.15 82.51 29.15 95.64

1.20 3.94 5.20 17.06 9.20 30.18 13.20 43.31 17.20 56.43 21.20 69.55 25.20 82.68 29.20 95.80

1.25 4.10 5.25 17.22 9.25 30.35 13.25 43.47 17.25 56.59 21.25 69.72 25.25 82.84 29.25 95.96

1.30 4.27 5.30 17.39 9.30 30.51 13.30 43.64 17.30 56.76 21.30 69.88 25.30 83.01 29.30 96.13

1.35 4.43 5.35 17.55 9.35 30.68 13.35 43.80 17.35 56.92 21.35 70.05 25.35 83.17 29.35 96.29

1.40 4.59 5.40 17.72 9.40 30.84 13.40 43.96 17.40 57.09 21.40 70.21 25.40 83.33 29.40 96.46

1.45 4.76 5.45 17.88 9.45 31.00 13.45 44.13 17.45 57.25 21.45 70.37 25.45 83.50 29.45 96.62

1.50 4.92 5.50 18.04 9.50 31.17 13.50 44.29 17.50 57.41 21.50 70.54 25.50 83.66 29.50 96.78

1.55 5.09 5.55 18.21 9.55 31.33 13.55 44.46 17.55 57.58 21.55 70.70 25.55 83.83 29.55 96.95

1.60 5.25 5.60 18.37 9.60 31.50 13.60 44.62 17.60 57.74 21.60 70.87 25.60 83.99 29.60 97.11

1.65 5.41 5.65 18.54 9.65 31.66 13.65 44.78 17.65 57.91 21.65 71.03 25.65 84.15 29.65 97.28

1.70 5.58 5.70 18.70 9.70 31.82 13.70 44.95 17.70 58.07 21.70 71.19 25.70 84.32 29.70 97.44

1.75 5.74 5.75 18.86 9.75 31.99 13.75 45.11 17.75 58.23 21.75 71.36 25.75 84.48 29.75 97.60

1.80 5.91 5.80 19.03 9.80 32.15 13.80 45.28 17.80 58.40 21.80 71.52 25.80 84.65 29.80 97.77

1.85 6.07 5.85 19.19 9.85 32.32 13.85 45.44 17.85 58.56 21.85 71.69 25.85 84.81 29.85 97.93

1.90 6.23 5.90 19.36 9.90 32.48 13.90 45.60 17.90 58.73 21.90 71.85 25.90 84.97 29.90 98.10

1.95 6.40 5.95 19.52 9.95 32.64 13.95 45.77 17.95 58.89 21.95 72.01 25.95 85.14 29.95 98.26

2.00 6.56 6.00 19.69 10.00 32.81 14.00 45.93 18.00 59.06 22.00 72.18 26.00 85.30 30.00 98.43