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Tidal characteristics and sounding datum variation in Lagos State

Article · July 2014

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Tidal Characteristics and Sounding Datum Variation

in Lagos State

Abstract: The need for water level monitoring has increased over the years. Water level monitoring

is among other things useful for oil and gas exploration and exploitation activities, and construction

of ports and harbour works. The mean sea level for Lagos, Nigeria is referenced to the Lagos datum

situated at the Office of the Surveyor General of the Federation at Lagos Island. This paper

examines correlation and variation in the mean water levels and sounding datums for twelve water

bodies in Lagos State. Water level observations were taken with the aid of tide gauges for twenty

nine days at 12 tidal stations strategically situated within Lagos State. The mean water levels and

other tidal characteristics for the various water bodies were calculated from the observed tidal

observations from the twelve tide gauge stations. The tide gauge station at the Lagos Harbour has a

known chart datum. Sounding datums were therefore determined for the eleven tide gauge locations

by sounding datum transfer technique using the Chart datum at the Lagos harbor. The result from

our study shows that there are variations in the tidal characteristics of the various water bodies in

Lagos State. There is also a need for the harmonization of the various tidal datum in Lagos State.

Keywords: Water Level Observations, Mean Water Level, Sounding Datum, Tidal Characteristics

O. T. Badejo

Senior Lecturer in Department of Surveying and

Geoinformatics, University of Lagos

J. B. Olaleye

Professor in the Department of Surveying & Geoinformatics,

University of Lagos

A. S. Alademomi

Lecturer in Department of Surveying and Geoinformatics,

University of Lagos, Nigeria

ISSN 2319-9725

July, 2014 www.ijirs.com Vol3 Issue 7

International Journal of Innovative Research and Studies Page 436

1. Introduction:

The Lagos lagoons lie behind the barrier beach and extend for 210 km along the coast. They

are flanked by tidal wetlands and swamps. We have about ten Lagoons in Lagos State, with

the Lagos and Lekki lagoons being the major lagoons among these lagoons. The other

lagoons are Yewa, Badagry, Ologe, Iyagbe, Kuramo, Apese, Epe, and Mahin lagoons

(Onyema, 2009b). Figure 1 and Figure 2 show the various Lagoons and Water Bodies in

Lagos State.

1.1. Lagos Lagoon:

The Lagos lagoon is more than 50 km long and 3 to 13 km wide. It is separated from the

Atlantic Ocean by a long sand spit to 5 km wide, which has swampy margins on the lagoon

side. Its surface area is approximately 6,354.7sq km. With the exception of the Commodore

channel, the lagoon is fairly shallow and is not plied by ocean-going ships, but by smaller

barges and boats. The Lagos Lagoon averages 2-4 m deep, but is 10 m deep in the entrance at

the Commodore channel. Lagos Lagoon empties into the Atlantic Ocean via Lagos Harbour.

The Lagos harbour or Commodore Channel is 0.5 km to 1 km wide and 10 km long. The

Lagos port is located at Apapa in a broad western branch off the main channel of the harbour.

The Lagos Lagoon is tidal, water from the Atlantic Ocean moves into the lagoon during high

tides and receeds during low tides. The Lagos lagoon is affected by a powerful longshore

drift. It is fed by several rivers, the most important of which are the Ogun, Ona/Ibu, Oshun,

Shasha and Oni.

1.2. Lekki Lagoon:

Lekki Lagoon, sometimes spelled Leeki, is located in Lagos and Ogun States in Nigeria. The

lagoon lies directly to the east of Lagos lagoon and is connected to it by a channel. The Lekki

lagoon is surrounded by many beaches (www.en.wikipedia.org/wiki/Lekki_Lagoon).

The mean depth of Lekki Lagoon is 3.1 m, and the maximum depth is 6.4 m at low tide. The

complex is isolated from the sea by the beach barrier ridges. The western channels approach

to within a few dozen metres to the sea, but in the east, much of Lekki Lagoon is situated 3-4

km inland. Tidal influence is not pronounced in Lekki Lagoon.



1.3. Ologe Lagoon:

The Ologe lagoon is a brackish water body and is situated northwards of Badagry creek.

River Owo is the main fresh water supply point into the Ologe lagoon (Clarke et al., 2004).

Partially treated and untreated effluents from the Agbara industrial estate is also discharged

into Ologe lagoon. The Ologe Lagoon opens into the Atlantic Ocean via the Badagry creeks

and the Lagos harbour.

The Ologe lagoon meets several socio-economic needs (aquaculture, fishing, sand dredging

and drainage) of the various towns and villages bordering it. Apart from providing income for

fishermen in the satellite towns and villages; it is also a sinkhole for their domestic wastes.

The lagoon is bounded by heavy industries including paper and pulp, glass, plastics,

breweries, pharmaceutical and beverages. These partially/largely untreated discharges

coupled with domestic inputs from the Agbara residential estates and satellite communities

cause significant levels of pollution (Clarke et al., 2005).

1.4. Badagry Lagoon:

The Badagry Lagoon is approximately 60 km long and 3 km wide, and lies between

longitudes 3°0′and 3°45′E and latitudes 6°25′and 6°30′N. Its water depth ranges from 1 m to

3m. Most of the year, the Badagry lagoon is characterized by fresh and slightly brackish

water. The lagoon is influenced by tides and floods from the Lagos Lagoon and Cotonou

harbour through Lake Nokue and Lake Porto-Novo (Anyanwu & Ezenwa, 1988).

2. Water Level Observation In Nigeria:

Sea level monitoring activities in Nigeria started as far back as the colonial years early in the

20th century. The primary objective of sea level monitoring activities at that time was for safe

navigation into the ports of Lagos, Port Harcourt and Calabar. Tidal data were observed at

these stations using graduated tidal staff and later upgraded to float types. Tidal predictions at

that time were very crude but were sufficient to allow ships to navigate through the shallow

estuaries and creeks to the ports.

The Lagos tide gauge station is a GLOSS designated station tied to a bench mark BM I. The

station was located at the jetty of the Nigerian Institute for Oceanography and Marine

Research (NIOMR) Lagos before it was washed away by floods in July 2000.



There is an international collaboration to monitor the sea level using tide gauges located all

around the coastal waters of the world. This network of tide gauges is called Global Sea

Level Observing System (GLOSS). The main component of GLOSS is the 'Global Core

Network' (GCN) of 290 sea level stations around the world for long term climate change and

oceanographic sea level monitoring. The present definition of the GCN (the definition is

modified every few years) is called GLOSS02 (JCOMM, 2011).

Nigeria is lagging behind as the nation is not within the GLOSS network. In the 1990s Shell

Nigeria made some effort to acquire tidal data along the Nigerian coastline. The data were

useful in tidal analysis and prediction. With sea level rising as a result of Global warming,

there is a need for Nigeria to acquire real time tidal measurements so as to be able to protect

our coastline. The entire Nigerian coastline, which is low-lying, is already experiencing the

adverse effects of sea level rise (SLR) through inundation and exacerbation of coastal

erosion. The impacts of SLR on the Nigerian coastal area were well articulated in

Vulnerability Assessment case study of the impacts of SLR on the Nigerian coast. (Awosika

et al., 1992, French and Awosika et al., 1995). For further reading on the history and science

of tides and sea level changes see Pugh(1987), Open University (1989), Emery and Aubrey

(1991), Bijlsmaet al. (1996), Pirazzoli (1996), Warricket al. (1996), Cartwright (1999) and

Douglas and Kearney (2000).

3. Lagos Datum:

Nineteenth and early twentieth century scientific studies of changes in sea level were

concerned primarily with vertical land movements in the belief that the average „real‟ level of

the sea is constant over long periods of time. Indeed, the original motivation for the

establishment of the IUGG Mean Sea Level Committee, which became the Permanent

Service for Mean Sea Level, was the requirement for a better sea level data set for the study

of post-glacial rebound in Scandinavia (Woodworth, 1993). Of course, it is now appreciated

that neither land nor sea levels are constant over long periods. There are vertical movements

of the land associated with a range of natural processes such as tectonics (e.g.,earthquakes) in

addition to post-glacial changes, and with a range of anthropogenic processes (e.g., ground

water pumping); for a review, see Emery and Aubrey (1991). Long term changes in mean sea

level relate to variations in ocean currents and to changes in the volume of water in the

oceans and therefore to climate change.



Lagos 1955 is a vertical datum first defined in 1955 and is suitable for use in Nigeria. Lagos

1955 origin is Mean sea level at Lagos, 1912-1928. Lagos 1955 is a vertical datum for

Geodetic survey, topographic mapping and engineering survey. It was defined by information

from Ebong et al, AVN International, 1991 (Geomatics Solutions 2011, Uzodinma 2005,

http://georepository.com/datum_5194/Lagos-1955.html). The Lagos Datum is 2.8310m

above mean sea level (British Oceanic Data Centre, 2011).

4. Tidal Characteristics And Sounding Level Determination:

The following steps constitute the methodology employed for investigating the water level

variation in Lagos State:

i. Office and Field Reconnaissance

ii. Establishment of Horizontal and Vertical Controls

iii. Erection of Tide Gauge Stations and Tidal Observations

iv. Reduction of Tidal Data and Computation of Tidal Characteristics

v. Sea Level Determination and Transfer of Tidal Datum

vi. Analysis of Tidal Data

4.1. Office And Field Reconnaissance:

The reconnaissance for the project was divided into two phases namely office reconnaissance

and field reconnaissance.

Extensive literature search was done to put the project in the right course. We got information

on a set of first order control points located at Mushin, Lagos State.

Field visit was done to familiarize ourselves with the nature of the project area. Hand held

GPS and a service boat was used for the reconnaissance. We also located existing shore

controls around University of Lagos and East Mole. The suitability of the controls was done

by carrying out spirit leveling. The sites for the tide gauge locations was carefully selected

based on the tidal range of the water bodies at different locations within Lagos State.



4.2. Horizontal And Vertical Control Establishment:

The Existing controls identified in section 5.1were used to establish 33 first order controls

around twelve tide gauge stations used for this study. Geodetic differential GPS observations

and levelling were used to determine the X, Y and Z coordinates of the 33 shore controls.

4.3. Erection Of Tide Gauge Stations And Tidal Observations:

Twelve tide gauge stations were established at the East Mole (Lagos Port) and at eleven other

stations. The tide gauges were located at tidally influenced water bodies that is on Lagos

lagoon, Lekki Lagon, Badagry creek and other lagoons within Lagos State. The zero level of

the tide gauges were also determined with the aid of spirit leveling and Total Station

traversing. The tide gauges were referenced to the shorecontrol stations.The Tidal

observations were carried out between October 3, 2008 and November 1, 2008. Figure 3

shows one of the established tide gauge stations.

4.4. Reduction Of Tidal Data And Computation Of Tidal Characteristics:

The observed tidal data at all the twelve tide gauge stations were reduced by applying the

zero level correction for all the tide gauge stations. The tidal curve was also smoothened by

removing spikes from the data. The spikes were either observation errors or errors in

converting the observed tidal data from analogue format to digital format.

The tidal characteristics of the observed data were computed. The tidal characteristics

computed for each of the tide gauge locations are the mean sea level, the mean high water

level, the mean low water level, the mean tide level and the range of the tide.

4.5. Sea Level Determination And Sounding Datum Transfer:

The observed tidal observations were reduced to the mean sea level by applying the zero

level corrections for each of the tide gauge station. The mean water level for each tide gauge

locality was computed from the reduced 29 days tidal data.

The sounding datum for each tide gauge vicinity was determined by computing the Mean

Low Water Springs for each tide gauge station. Since a limited tidal data was used to

compute the sounding datum, we transferred sounding datum from the standard port at East

Mole to the other tide gauge stations. The sounding datum transfer for each tide gauge



locality was done by using simultaneous 29 days tidal observations from the reference site at

East mole and the eleven tide gauge stations.

The distance of sounding datum below the observed mean level at any of the new site is the

distance of chart datum below the mean level at the reference site times the range ratio

(new/reference). Subtracting the observed height of the mean level from the value of the

distance of the sounding datum below the observed mean level at any of the new sites gives

the distance of the sounding datum below the gauge zero at any of the new sites.

The range ratio method assumes that the ratio of the vertical distances from the respective

datum planes to mean high water springs (MHWS) at the reference and subordinate sites

(MHWS/mhws) is equal to the ratio of the observed mean tidal range at the same two sites

(MR/mr). Thus, the ratio is given as:

MHWS/mhws = MR/mr 5.1

Marshall (2007) gives the full details of the tidal datum transfer procedures used. This

method was chosen because of its proven accuracy. However, other methods may be better

suited to other sites depending on their physical and tidal characteristics. For example, in

some locations only part of the tidal range can be observed because of the influence of mud

flats. In this case the modified height difference method (Dewar and Hannah, 2005) could be

used. The least squares method (Grant and O'Reilly, 1986) may be particularly suited to the

high rate GPS buoy data, however this requires further investigation.

4.6. Analysis Of Data And Tidal Characteristics:

Tidal characteristics was done to determine the mean sea level, mean tide level range and

sounding datum of the water bodies in Lagos State. The analysis of the reduced tidal data was

also performed by testing the equality of the mean sea level for the twelve tide gauge stations.

Analysis of Variance (ANOVA) test was done for the test.

5. Results And Analysis Of Results:

The results and the analysis of the work carried out are presented in the followings sections.



5.1. Results:

The results of our work are given in tables 1 to 6.

5.2. Analysis Of Results:

The analysis of the results for this work is presented as follows and also shown in table 6:

H0: µ1= µ2= µ3

H1: At least two means differ

The test statistics is F.

F = MST/MSE

MST= SST/K-1

Where MST is mean square for treatments MSE is mean of squares for error

SST is sum of squares for treatments

K is no of treatments

K = 12

MSE = SSE/n-k

n = n1+n2+n3+……+n12

Let α = 0.05

Rejection region = F>Fα, k-1,n-k

MST = SST/K-1

SST =6127.3685

K=12

MST = 557.0335

MSE = SSE/n-k

SSE=341.5285675



n = n1+ n2 + n3+ ……+ n12

n = 16831

n-k =16819

MSE =0.02030612

F = MST/MSE

F = 27431.809

α = 0.05

Rejection region = F>Fα, k-1,n-k =1.75

There is enough evidence to infer that the monthly mean sea level differ between the 12 tide

gauge station areas.

Table 5 shows thedifference of observed and transferred sounding datums. A close

observation of table 7 shows that there is no marginal difference in the values of the sounding

datum from the observed tidal data and from the values transferred from East Mole. Except

for East Mole and Olooge Lagoon, the differences from the two sets of values are less than

0.1m. An error of 0.1m is tolerable for most hydrographic operations. The reason for the little

difference in the two set of values for the sounding datums is that the tidal observations

covered just one month. The highest difference in the two sets of observations is from the

values for East Mole which is -0.181m. Our finding from the one month observation is that

the value of 0.38m below the mean sea level adopted for East Mole as the Chart Datum is

actually not correct. We were able to get tidal observation that was as low as 0.561m below

the mean sea level. That means the chart datum of East Mole should be lower than 0.38m

below the mean sea level.

In this work, we actually use the difference in the observed mean water level and the lowest

observed water level at East Mole (instead of 0.38m below the sea level) for the transfer of

sounding datum to other tide gauge locations.

Table 6 shows thedifference of Mean Water Level and Mean Tide Level.A careful study of

table 8 shows that there is little or no difference in the values of the mean sea level and that of



the mean tide level. Thus where the value of the mean sea level is not available, the mean tide

level can be used approximately for that of the mean sea level.

6. Conclusion And Recommendation:

This section contains the conclusion of our study and the recommendations based on findings

in the work. Sections 7.1 and 7.2 contain the conclusion and the recommendations.

6.1. Conclusion:

We have successfully identified tidally influenced water bodies in Lagos State and taken

water level observations with the aid of tide gauges for twenty nine days at 12 tidal stations

strategically situated at tidally influenced water bodies in Lagos State. In addition, we

adequately computed the tidal characteristics at the tide gauge locations. The tidal

characteristics captured include the mean water level, mean tide level, men high waters, mean

low waters and the range of the tide.

Anova statistical test was done to test the equality of the various mean sea level from the 12

tide gauge stations. The statistical results show that there is enough evidence to infer that the

monthly mean sea level differ between the 12 tide gauge station areas.

The Chart Datum for East Mole (Lagos Port) is given as 0.38m below the mean sea level.

The distance of the sounding datum below the observed mean water level for the eleven tide

gauge locations were determined by multiplying the distance of the sounding datum at East

Mole by the ratio of the range of observed tide at new gauge locations to the range of the

observed tide at East Mole.

The sounding datum for the twelve tide gauge locations were also determined from observed

tidal observations. Each of the tide gauge station was referenced to survey controls we

established in the vicinity of the tide gauges. Thus the reduced readings from each of the tide

gauge actually show the water level above or below the mean sea level. The mean lower low

waters was taken as the sounding datum for each of the tide gauge locations.

The values of the distance of the sounding datum below the observed mean water level for

the two methods were carefully observed and the small differences in their values indicate

that there is no marginal difference in their values.



Our finding from the one month observation is that the value of 0.38m below the mean sea

level adopted for East Mole as the Chart Datum is actually not correct. We were able to get

tidal observation that was as low as 0.561m below the mean sea level. That means the chart

datum of East Mole should be lower than 0.38m below the mean sea level.

We also discovered that there is little or no difference in the values of the mean sea level and

that of the mean tide level. Thus where the value of the mean sea level is not available. The

mean tide level can be used.

6.2. Recommendation:

The following recommendations are made based on our study:

Further studies on tidal characteristics for the water bodies within Lagos State with at

least a year‟s tidal data should be carried out.

The information on the tidal characteristics from this work can in the interim be

adopted and made available to the public to assist in the various marine projects

within the state.

Governmental and non governmental agencies should work together with those in the

tertiary institutions to improve upon what has been done in this work especially to

harmonize the datums in Lagos State.

The Chart datum for Lagos Port should be redefined as the level chosen as the chart

datum is not low enough.

S/N

Name of

Location

Mean

Sea

Level

(m)

Mean

High

Water

(m)

Mean Low

Water (m)

Mean Tide

Level (m)

Range of

Tide(m)

1

East Mole

(Lagos Port) 0.232 0.657 -0.224 0.217 0.881

2 Ajido 1.128 1.215 1.058 1.137 0.157



3 Badagry 1.380 1.429 1.338 1.384 0.091

4 Epe -0.299 -0.238 -0.349 -0.293 0.112

5 Ikorodu 0.461 0.628 0.315 0.472 0.313

6 Ikosi 0.114 0.219 0.026 0.123 0.193

7 Lekki -0.453 -0.432 -0.440 -0.436 0.008

8 Ojo/Port- 0.740 1.006 0.437 0.722 0.569

Novo

9 Olooge 1.033 1.064 1.001 1.033 0.063

10 Oreta 0.243 0.394 0.108 0.251 0.286

11

University of

Lagos 0.456 0.613 0.317 0.465 0.296

12 Yewa 1.513 1.541 1.481 1.511 0.060

Table 1: Tidal Characteristics

S/N

Name of

Location

Mean

Water

Level

(m)

Mean

Lower

Low

Water

Spring

(Sounding

Datum)

(m)

Range at

Establishe

d

Gauge R

(m)

Tidal

Range

at

New

Tide

Gauge

Location

s r (m)

Distance

of

Chart

Datum

Below

Mean

Water

Level at

Referen

ce

Gauge

(m)

Distance

of

Sounding

Datum

Below

Mean

Water

Level(D)

(0.61*r/R)

(m)

Sounding

Datum

Above

Mean Sea

Level (m)



1

East

Mole

(Lagos

Port) 0.232

-0.561

0.881 0.612 -0.380

2 Ajido 1.128 0.97 0.157 0.109 1.018

3 Badagry 1.380 1.253 0.091 0.063 1.317

4 Epe

-

0.299

-0.404

0.112 0.078 -0.377

5 Ikorodu 0.461 0.206 0.313 0.217 0.244

6 Ikosi 0.114 -0.081 0.193 0.134 -0.020

7 Lekki

-

0.453

-0.547

0.008 0.006 -0.459

8

Ojo/Port

Novo 0.740

0.314

0.569 0.395 0.345

9 Olooge 1.033 0.886 0.063 0.044 0.989

10 Oreta 0.243 0.026 0.286 0.199 0.044

11

Universit

y of

Lagos 0.456

0.24

0.296 0.205 0.250

12 Yewa 1.513 1.388 0.060 0.042 1.471

Table 2: Results of Sounding Datum Determination

Bada

gry

East

Mole

Ep

e

Ikoro

du

Iko

si

Lek

ki

Oloo

ge

Ore

ta

Aji

do

Ojo Port

Novo

Unil

ag

Ye

wa

1.34 -0.12

-

0.3

3 0.45

0.1

5

-

0.49 1.01 0.26 1.11 0.74 0.45 1.46

1.34 -0.14

-

0.3

1 0.41

0.1

8

-

0.50 1.01 0.17 1.09 0.62 0.41 1.47

1.33 -0.12 -

0.36 0.2 -

1.01 0.13 1.06 0.52 0.37 1.47



0.3

2

0 0.48

1.32 -0.07

-

0.3

4 0.32

0.1

7

-

0.48 1.00 0.12 1.04 0.46 0.34 1.47

1.30 0.13

-

0.3

5 0.32

0.1

3

-

0.47 0.99 0.11 1.01 0.49 0.33 1.46

1.28 0.23

-

0.3

6 0.34

0.0

6

-

0.47 0.98 0.12 1.00 0.60 0.36 1.44

1.27 0.38

-

0.3

7 0.39

-

0.0

1

-

0.48 0.97 0.19 1.00 0.73 0.41 1.44

1.28 0.43

-

0.3

8 0.47

-

0.0

1

-

0.47 0.96 0.25 1.03 0.83 0.48 1.43

1.30 0.43

-

0.4

0 0.54

0.0

4

-

0.48 0.97 0.30 1.07 0.90 0.54 1.43

1.32 0.33

-

0.3

8 0.58

0.1

0

-

0.49 0.98 0.35 1.11 0.94 0.57 1.43

1.35 0.18

-

0.3

2 0.58

0.1

6

-

0.50 0.99 0.36 1.14 0.94 0.57 1.44

1.37 0.03 -

0.20.54

0.2

0

-

0.51 1.02 0.34 1.15 0.88 0.50 1.47



9

1.37 -0.17

-

0.2

6 0.47

0.2

2

-

0.51 1.03 0.27 1.13 0.77 0.46 1.49

1.35 -0.32

-

0.2

6 0.42

0.1

7

-

0.49 1.02 0.22 1.10 0.65 0.40 1.49

1.33 -0.34

-

0.2

5 0.37

0.1

4

-

0.49 1.03 0.15 1.07 0.52 0.34 1.48

1.32 -0.32

-

0.2

9 0.33

0.0

9

-

0.49 1.02 0.10 1.04 0.41 0.30 1.48

1.31 -0.17

-

0.3

2 0.28

0.0

6

-

0.48 1.02 0.07 1.02 0.36 0.27 1.47

1.28 -0.02

-

0.3

2 0.26

0.0

2

-

0.47 0.99 0.06 1.00 0.39 0.26 1.46

1.28 0.18

-

0.3

2 0.29

0.0

1

-

0.49 0.98 0.06 0.98 0.51 0.27 1.45

1.27 0.28

-

0.3

4 0.32

0.0

0

-

0.48 0.97 0.08 0.99 0.63 0.31 1.44

1.27 0.36

-

0.3

5 0.39

0.0

1

-

0.49 0.96 0.15 1.01 0.72 0.38 1.42



1.28 0.38

-

0.3

6 0.43

0.0

2

-

0.48 0.96 0.23 1.03 0.78 0.44 1.42

1.28 0.25

-

0.3

7 0.47

0.0

6

-

0.48 0.96 0.26 1.05 0.82 0.48 1.42

1.30 0.08

-

0.3

5 0.52

0.1

1

-

0.48 0.96 0.28 1.07 0.82 0.47 1.43

Table 3: Tidal Readings for Water Bodies in Lagos State on October 5 2008

S/N

Name of

Location

No of

Observations

(n)

Summation

of

Observations

Mean

Water

Level

(m)

Grand

Mean

(m)

(Mean

Water

Level

-

Grand

Mean

)

(d)

(m)

n(Square

of d)

Sum(Square

(Xi-Mean

Water

Level))

1

East Mole

(Lagos Port) 1403 325.667 0.232 0.543 -0.311 135.59322 159.8831262

2 Ajido 1405 1584.490 1.128 0.543 0.585 480.41671 11.53449281

3 Badagry 1403 1936.839 1.380 0.543 0.837 984.06878 8.570718746

4 Epe 1405 -420.150 -0.299 0.543 -0.842 996.18704 6.885322848

5 Ikorodu 1403 647.038 0.461 0.543 -0.082 9.4411534 20.06662865

6 Ikosi 1405 160.695 0.114 0.543 -0.429 258.12735 10.48312883

7 Lekki 1426 -646.050 -0.453 0.543 -0.996 1414.7582 1.607778365

8 Ojo/PortNovo 1355 1002.490 0.740 0.543 0.197 52.503488 62.92210745

9 Olooge 1405 1450.920 1.033 0.543 0.490 336.90454 5.350544057



10 Oreta 1426 346.366 0.243 0.543 -0.300 128.43122 18.6233378

11

University of

Lagos 1392 634.430 0.456 0.543 -0.087 10.59215

18.96097751

12 Yewa 1403 2123.054 1.513 0.543 0.970 1320.3446 16.64040428

Sum 16831 9146 7 SST= 6127.3685 341.5285675

Mean of Sea

Levels

0.5456

6

Grand

Mean =

0.543389519 SSE=

341.5285675

Table 4: Analysis of Observed Tides

S/N

Name of

Location

Sounding

Datum

Below

(Above)

Mean Sea

Level

Mean Lower

Low Water

Spring

(Sounding

Datum) MLLWS-S.D.

1

East Mole

(Lagos Port) -0.380

-0.561

-0.181

2 Ajido 1.018 0.970 -0.048

3 Badagry 1.317 1.253 -0.064

4 Epe -0.377 -0.404 -0.027

5 Ikorodu 0.244 0.206 -0.038

6 Ikosi -0.020 -0.081 -0.061

7 Lekki -0.459 -0.547 -0.088

8 Ojo/Port- 0.345 0.314 -0.031



Novo

9 Olooge 0.989 0.886 -0.103

10 Oreta 0.044 0.026 -0.018

11

University

of Lagos 0.250

0.240

-0.010

12 Yewa 1.471 1.388 -0.083

Table 5: Difference of Observed and Transferred Sounding Datum

S/N

Name of

Location

Mean

Water

Level (m)

Mean Tide

Level (m)

M.T.L.-

M.W.L. (m)

1

East Mole

(Lagos Port) 0.232 0.217 -0.015

2 Ajido 1.128 1.137 0.009

3 Badagry 1.380 1.384 0.003

4 Epe -0.299 -0.293 0.006

5 Ikorodu 0.461 0.472 0.011

6 Ikosi 0.114 0.123 0.008

7 Lekki -0.453 -0.436 0.017

8 Ojo/Port-

Novo

0.740 0.722 -0.018

9 Olooge 1.033 1.033 0.000

10 Oreta 0.243 0.251 0.008

11 University of 0.456 0.465 0.009



Lagos

12 Yewa 1.513 1.511 -0.002

Table 6: Difference of Mean Water Level and Mean Tide Level

Figure 2: Water Bodies in Lagos State

Figure 1: Lagoons and Water Bodies in Lagos State



Figure 3: One of the Established Tide Gauge Stations used for the Study

Figure 4: Tidal Curve of Water Bodies in Lagos State on October 5 2008



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