02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 1 Sea Level Variations along the Red Sea Coasts Tarek M. El-Geziry (PhD) Researcher Laboratory of Physical Oceanography Division of Marine Environment National Institute of Oceanography & Fisheries (NIOF)

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 2 Outlines The Red Sea Tides Tide Gauge Network along the Red Sea Coasts Characteristics of Tides in the Red Sea What about the steric effect? Tidal Currents Tides & Development Conclusions

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 3 The Red Sea NNW-SSE Latitudes: o N Longitudes: o E Egypt, Sudan, Ethiopia & Djibouti: Western Boundaries Jordan, Saudi Arabia & Yemen: Eastern Banks Surface Area of 450*10 9 m 2 Average Depth of 450 m (Madah et al., 2015)

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 4 The Red Sea Connections to Gulfs through straits: - Gulf of Aden (Strait of Bab El-Mandab) -Gulf of Suez (Strait of Gulf of Suez) -Gulf of Aqaba (Straits of Tiran) (Madah et al., 2015)

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 5  At any location, the observed sea level is the sum of two different components: the astronomical tides (Celestial impact) and the residual sea level (Steric effect). Tides

NameSymbol% of ImportancePeriod (Solar hr.) Principal lunarM2M Principal solarS2S Larger lunar ellipticN2N Luni-solar semidiurnalK2K Larger solar ellipticT2T Smaller solar ellipticL2L Lunar elliptic second order2N Larger lunar evectionalν2ν Smaller lunar evectionalλ2λ Variationalμ2μ Luni-solar diurnalK1K Principal lunar diurnalO1O Principal solar diurnalP1P Large lunar ellipticQ1Q Smaller lunar ellipticM1M Small lunar ellipticJ1J Lunar fortnightlyMf Lunar monthlyMm Solar semi-annualSsa (Pugh, 1987) Tidal Constituents

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 7 Types of Tides F = (O1+K1)/(S 2 +M2 ) 0 – 0.25 Semidiurnal Tides 0.25 – 1.5 Mixed Semidiurnal 1.5 – 3.0 Mixed Diurnal 3.0 Diurnal

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 8 Tide Gauge network Along The Red Sea coasts (Sammari, 2004)

02-04 Feb Characteristics of Tides in the Red Sea Tides in the Red Sea are mainly of semi-diurnal types, i.e. Two Highs and Two Lows occur per day almost 6 hours. (Madah et al., 2015)

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 10 The highest observed tidal range occurs at the northern and the southern tips of the Red Sea are Characteristics of Tides in the Red Sea (Abohamida & Rakha, 2013)

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 11 The tidal range decreases toward the central part of the Red Sea and an amphidromic system exists off Port Sudan. Characteristics of Tides in the Red Sea (El-Taib, 2010)

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 12 Changes in sea level due to steric changes are mainly attributed to the variations in seawater temperature and salinity, and hence, in density. The term can also refers to the meteorological parameters, which impact on the sea level e.g. wind speed, atmospheric pressure. What about the Steric Effect?

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 13 What about the Steric Effect? (Eid & Kamel, 2004)

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 14 A tidal current changes its velocity and direction through tidal cycles especially during Slack Water. Tidal Currents

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 15 Tidal Currents (Abohamida & Rakha, 2013) The maximum tidal current velocity along the Red Sea

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 16 Tides & Development Tides have special importance to mariners, oceanographers and society as they are used: T o determine safe times to enter/drive ships to/from ports. T o determine a chart datum used for nautical surveys. T idal diamonds are used for safe navigation as they determine speed (knots) and directions of currents during spring and neap tides. ( Tidal_diamond#mediaviewer/File:Nautical_chart_tidal_diamond.PNGTidal_diamond#mediaviewer/File:Nautical_chart_tidal_diamond.PNG) Tidal Diamonds

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 17 Tides & Development Also, The vertical variations in the sea level and the associated horizontal currents help in the purification processes of seawater and in enhancing the situations of estuaries and outlets. Tidal energy itself has been used since the 11 th century when small dams were built along ocean estuaries and small streams in order to turn water wheels used in the milling of grains, e.g. Eling Tide Mill in England.

Lastly, In the modern age, tides are used to drive turbines to produce electricity either using the potential energy (tidal range) or the kinetic energy (tidal streams) La Rance tidal plant, France ( The SEAFLOW tidal turbine ( _files/Seaflow_raised_16_jun_03b.jpg) _files/Seaflow_raised_16_jun_03b.jpg Tides & Development

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 19 Conclusions Tides are well observed along the Red Sea coasts, however, only a few literature can be found on its description and analysis. Factually  the major research on the sea level variations is for the central part of the Red Sea (Jeddah, Jizan, Dubah, Port Sudan) and for the northern tip of the Gulf of Aqaba, with a very limited work along the Egyptian side.

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 20 Conclusions Although tides are well observed along the Red Sea coasts, their impact on the plans of development can be limited to: 1.Navigational development (Harbours & Charts) 2.Coastal Constructions 3.Near-shore Coral Communities

02-04 Feb.2016Workshop on Development of the Red Sea Environment & Fisheries 21