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The Geographical Features Of The Maltese Islands Environmental Sciences Essay

As explained in the first chapter of this dissertation, this research is an extensive and complex one which needs lots of thinking and effort. It is a combination of a series of researches, interpretations, studies, examinations, data collection and analyses while at the same time illustrating all the above with graphs, figures, tables and plates. Therefore, this chapter will link all the previous stages involved in this dissertation as well as providing suitable conclusions on each one. Moreover, a summary of all the data sets of each bay will be provided after discussing these same results in accordance to the hypotheses and objectives stated initially.

The main reason behind the work of such a dissertation is to provide further information and a general academic value to the geographic identity of the Maltese Islands. As already stated in the introduction chapter, there is still more work and progress to be made in the physical aspect and studies of this island. Research has already taken a huge leap forward with more funds that are being invested in such studies. All the methods and approaches used along this dissertation were already established and are frequently used worldwide. Therefore this is done to provide more academic value to the beaches on these islands especially towards their sedimentological characteristics.

Since this research is for academic use, there was the need to produce a strong and reliable literature review on which to base all of the studies accomplished. The coast is an integral part of the world’s surface and is established as being ‘a region of transition between land and sea’ (Stratton Commission, 1969). It is important to classify the coast into various forms in order to identify what to analyze when viewing the ideal study with the real-case scenario. Each classification is divided into other smaller morphologies which are important so as the research is specific, especially when choosing the area of study. The coast may be divided into four main morphologies: backshore, foreshore, inshore and offshore. However, as stated in the title, the nearshore will be studied which is a combination of the preceding first three morphologies. Shingle beaches are established as those beaches having sediment ranging between 2mm and 256mm (Pye, 2001). The involvement of a series of statistical conjugations derived from the data collected is important to provide scientific facts to the findings. Sediment properties were established using the following well known equations: Cailleux Flatness (1947), Cailleux Roundness (1947), Folk and Sneed Sphericity (1958), Ouma Roundness (1967), Riviere and Ville Morphological Index (1974), Scheiderhohn Elongation (1954), and Wadell Roundness (1932).

Waves are a determining factor in the development and constant variation of a beach. Waves may either erode or deposit sediment according to their original force as well as having a direct influence on the beach profile. The longshore drift, on the other hand, effects the extent to which the sediment will be transported thus also playing an important role in determining sediment shape, size and other properties. Human influence is an important manipulator in either the prevention or enhancement of coastal geomorphological changes, which can have any negative or positive effects.

Identifying Objectives and Hypotheses

The number of objectives initially stated in this dissertation will be discussed, analyzed and verified or dispoved. To discuss these objectives, two tables will be presented in this section which invol€ve a summary of all the data previously collected and examined. Table 1 provides the type of change that is occurring to each of the beach’s characteristics as well as the sediment properties from summer to winter. This is made in order to identify which variable increases or decreases on value together with viewing the similar patterns occurring within the three studied bays. In order to do this, all the data sets recorded were used and a mean result for each single variable was calculated. When the data recorded in summer was higher than that in winter an increase was recorded and vice-versa. Table 2 indicates the total mean of each shingle variable collected from the studied bays. It does not take into consideration the season or quadrat they were collected in but are divided in accordance to their respective line transects. This is done in order to view how each sediment variable varies according to their position along the bay.

Characteristics:

Bay Under Observation

Ġnejna

Qrajten Point

Mistra

Length Of Beach

Decrease

Increase

No Change

Width Of Beach

Decrease

Increase

Increase

Area

Decrease

Increase

Increase

Amount of Sediment Collected

Increase

Decrease

No Change

Longshore Drift

Increase

Increase

Increase

Depth of Water

Decrease

Decrease

Increase

Infiltration Rate

Increase

Decrease

Decrease

Slope Profile

Decrease

Increase

Increase

Sediment Properties:

Length

Decrease

Increase

Increase

Breadth

Decrease

Increase

Increase

Height

Decrease

Increase

Increase

Morphological Index

Decrease

Increase

Increase

Cailluex Flatness

Decrease

Increase

Decrease

Folk and Sneed Sphericity

Increase

Decrease

Decrease

Scheiderhohn Elongation

Increase

Increase

Increase

Ouma Roundness

Increase

Increase

Increase

Cailleux Roundness

Increase

Increase

Increase

Wadell Roundness

Increase

Increase

Increase

Maximum Projection

Decrease

Increase

Increase

Increase Volume

Decrease

Increase

Increase

Table 5.1: The changes of each bay characteristic and sediment property occurring from summer to winter.

Bay:

Ġnejna

Mistra

Qrajten Point

Line Transect:

1

2

3

1

2

3

1

2

3

Variables

Length

55.23

66.23

102.11

54.15

52.16

63.41

64.41

108.8

104.58

Breadth

42.44

48.99

76.29

40.33

38.28

45.87

48.08

75.90

76.82

Height

29.58

32.72

53.82

27.55

27.65

31.39

31.62

43.95

46.08

Morphological Index

1.4512

1.6055

1.4748

1.5463

1.4402

1.5444

1.6285

1.8248

1.7207

Cailluex Flatness

171.05

189.30

174.74

184.19

172.56

181.50

188.15

215.1

207.38

Folk and Sneed Sphericity

0.6259

0.5717

0.6138

0.5883

0.62045

0.59032

0.5743

0.5189

0.5323

Scheiderhohn Elongation

0.7793

0.7503

0.7574

0.75580

0.74381

0.74188

0.7413

0.7263

0.7327

Ouma Roundness

0.48441

0.50788

0.49167

0.4568

0.43971

0.50984

0.5248

0.4977

0.4585

Cailleux Roundness

479.7

475.2

468.9

458.5

443.8

487.3

524.0

499.5

430.1

Wadell Roundness

0.37377

0.37836

0.37397

0.34363

0.33301

0.38117

0.38778

0.3602

0.3318

Maximum Projection

2013

3027

6621

2484

1933

3316

3963

11205

9556

Volume

45888

90349

273935

88506

52855

160853

210654

733997

599581

Table 5.2: The total mean of each shingle variable collected from the studied bays.

The next step is to view each objective and hypothesis stated in the introduction of this dissertation and view how they were tackled. Each objective will be discussed separately using Table 1 and Table 2, together with other data previously mentioned.

Dissertation Objectives

Beach steepness is affected by wave energy.

This first objective was already discussed in Chapter 2.3.1 and well explained by Natarajan, Mohan, & Balasubramanian (2008). The wave energy will be measured in accordance to the wind speed perpendicular to the bay under study. Ġnejna Bay has the strongest and most frequent wind, followed by Qrajten Point and finally Mistra Bay. The highest slope ratio is in Qrajten Point while the lowest slope ratio is at Mistra Bay, both in winter and summer. This evaluation shows that wind energy is not the main influence in the determination of the slope ratio meaning that there are other physical properties which control the latter. A particular physical property which follows the same pattern as the beach slope is the longshore drift. The longshore drift is influenced by the fetch of the beach. The highest longshore drift and fetch are at Qrjaten Point while the lowest result in Mistra Bay which is similar to the slope ratio described before. Another interesting point is that as the slope ratio of the beach decreases, so does the mean width of shingle beach, and vice-versa.

Beach length is influenced by geomorphology and particles size.

Mistra Bay and Ġnejna Bay consist of a number of faults which altered the whole geology of the area while Qrajten Point is dominated by Globigerina Limestone. Globigerina Limestone is easily eroded and this resulted in Qrajten Point having the biggest fetch while it has the smallest overall beach length. This shows that faulting has a greater effect on the beach length rather than the actual geology of the area. It was found that when the overall length of the beach decreases, the mean length of the shingle decreases between seasons, and vice-versa. Mistra Bay has the longest shingle beach but has the smallest particle size as compared to the other two bays. This means that there is a relationship between the beach length and the sediment size. This study shows that these two variables act similarly in seasonal changes because when one decreases the other decreases and vice-versa.

Shingle Sphericity is influenced by the shingle beach width together with season and permeability.

It is evident in Table 5.1 that as the width of each beach increases, the shingle sphericity index increases while the shingle volume decreases. From this observation it may be concluded that the more spherical the sediment the easier it is to be transported inland by wave action making the beach wider. When it comes to compare the shingle sphericity with the change in season there is no particular pattern since in Ġnejna Bay it increases while in the other two bays the sphericity decreases from summer to winter. This results that the wind speed has a direct effect on this beach morphology since Ġnejna Bay has the strongest wind force making the width decrease between seasons. Therefore, one may conclude that a strong wind force will have the strength to transport shingle seawards thus making the shingle beach width narrow and the shingle spherical. Finally, the permeability is directly proportional to the shingle sphericity. The reason behind this is that when the shingle situated on a beach is more spherical, then the pores between them is larger thus allowing more water to infiltrate.

Anthropogenic activity influences directly beach sedimentation.

The anthropogenic influence on each beach, especially on sediments, is based upon the author’s view and opinion and therefore is subject to change. Ġnejna Bay is the least influenced while Qrajten Point is the most influenced by human activities. Qrajten Point surroundings are mostly subject to concrete walls, constant developments as well as past construction waste dumped close by. In Mistra Bay a cement ramp is built in the middle of the bay together with a few houses and a road passing by. The worst influence of all is that cars park on the beach and boat owners move shingle to make it easier for larger boats to be placed on shore. Ġnejna Bay has a seawall behind the beach and a number of jetties constructed with adjacent boat houses. These constructions were built in line with the coastline and together with the jetties they reduce their impact on the course of sedimentation.

For the sediment change from summer to winter, the major morphological indexes of a shingle were used. The following equation is applied:

.

where: s is the summer result and w is the winter result. In this equation, modulus is used in order to produce the absolute value of the figures produced and thus avoid negative results. Each characteristic is squared in order to avoid negative results. The final result was that Qrajten Point has the biggest sediment change followed by Mistra Bay and finally Ġnejna Bay. There is a high difference between the result of Qrajten Point and that of Ġnejna Bay. To conclude, human activities influence the sedimentation patterns resulting in that the more human activities occurring in the area, the higher the sediment changes are from summer to winter. There are other factors that influence sediment property changes from summer to winter such as longshore drift and wind speed but surely human activities are an additional factor which quickens the process.

Bays are directly affected by wind direction along the Maltese Islands.

The lower the wind influence on the area, the lower the fetch, the lower the longshore drift and the smaller sized sediments have been found on the bay. On the other hand, areas with higher wind speeds have a smaller shingle area as it influences the length and width of each bay.

Beaches named differ according to their location.

Ġnejna bay is situated on the western part of the island and is influenced by faulting and strong frequent winds. All this has a direct influence on the sediment properties found in the area. From summer to winter there is an increase in the sediment length as well as in the morphological index, flatness, sphericity, and maximum projection. What is happening to the sediment in Ġnejna Bay is the opposite of what is occurring in the other two bays where all the sediment properties previously named decrease between seasons. As a result, Ġnejna bay is more prone to erosion particularly as there is a decrease in the slope profile from summer to winter. This decrease in the slope profile transports the sediment closer to the mean waterline. For this reason, sphericity of shingle collected increase from summer to winter making this same sediment more rounded and finer. Hence, wind has the major influence on the beach morphology since Ġnejna Bay may be best combined to this objective.

Beaches named differ according to season

As remarked in Table 5.1, almost all variables’ data collected varies from summer to winter. The only two variables not to change are the beach length and the amount of sediment collected at Mistra Bay. This is because the length of the bay is enclosed and thus it is not possible to change, while the amount of sediment collected reached the maximum amount calculated to be measured in both seasons. The following equation was used in order to calculate the seasonal change in the three bays:

Overall Seasonal Change = + + + + ( + (Sediment Change).

From this equation the results were similar to those explained in Section 5.2.4 in which the highest overall seasonal change is in Qrajten Point followed by Mistra Bay and finally Ġnejna Bay.

Analyzing various methods used in establishing shingle roundness and choosing the best possible outcomes.

This objective was discussed in Chapter 4.14.1 where after taking a detailed look at the different results obtained from calculating the roundness of the sediment collected it was concluded that the best equation is the Ouma Roundness. This is so because of a number of factors: (a) the Cailleux Roundness had obtained figures larger than its original maximum, that of 1000 and also had a probability plot which differed slightly from that originated from the data, and (b) the scatter plot of the Wadell Roundness and the box plot confirm that the data range is low.

Dissertation Hypotheses

Shingle properties vary according to the longshore drift direction

This hypothesis may be easily linked to the objectives previously explained. The longshore drift may be easily linked to particular shingle properties as they follow the same patterns of variation. First of all, the longshore drift must be related to the physical changes occurring in a bay. The higher the angle of longshore drift was in the bays, the higher was the fetch, the infiltration rate, the slope ratio and the seasonal change. Therefore, the longshore drift, fetch, infiltration rate and slope ratio have an influence on one another and these will eventually control all of the factors varying from summer to winter.

As the longshore drift increased from summer to winter in all the three beaches, two shingle properties also commonly increased (Table 5.1). The shingle elongation and roundness increased from summer to winter in Ġnejna Bay, Mistra Bay and Qrajten Point and therefore these two can be associated with the increase in the longshore drift angle.

There is a relationship between the mean shingle height and the longshore drift direction (Table 5.2). The longshore drift direction is from line transect three to line transect one while the height of the shingle collected and analyzed decreased from L3 to L1. This is because at L3 new shingle is deposited while at L1 the longshore drift becomes less effective and starts to deposit smaller sediment which are easier to be transported.

Beach morphology varies according to the wind direction and force as well as the shingle properties

First of all to describe this hypothesis each terminology used in this phrase must be identified and explained. The beach morphology includes the length and width of the same beach together with the slope ratio.

From the previous objectives, it was discussed that when the wind speed is high there is a low slope profile together with a decrease in the length and width of the shingle beach. When such beach morphologies occur, the sediment found will be altered in concurrence to such morphologies. As a result, there will be an increase in the shingle sphericity while on the other hand there will be a decrease in the same shingles’ mean length, morphological index and flatness. This shows that the two most variable shingle properties which are easily varied and changed according to their physical surroundings are sphericity and flatness.

Conclusion

As a general overview of the seasonal change occurring in each bay from summer to winter Figure 5.1 is produced using the equation provided in section 5.2.1.4. This figure shows the graph of the seasonal change value against the Ln (seasonal change value) [the values are illustrated in Appendix D]. The same values produced by the are engaged as an index rating.

Figure 5.1 : Rating the seasonal change in the bays under study.

It is important to notice that all the shingle properties used to produce the equation results all use the length/breadth and height of the same shingle in meters. This is done in order to have more accurate results and avoid high values in the seasonal change outcome. From Figure 5.1 it can be observed that for a low seasonal change value the rating increases rapidly, whilst after reaching the point of threshold, the rating increases at a decreasing rate with the increase in seasonal change. Ġnejna Bay is the closet point to the threshold having a seasonal change value of 8.7 whilst having a rating of 2.2 on the scale. This graph can be easily applied to various other bays which sediment could be studied in the near future and thus having a broader view of how such beaches would differ amongst one another.

To conclude this dissertation, the following table was produced in order to provide a summary of the whole discussion discussed in Chapter 4. Table 5.3 consists of a comparison between the three bays involved in this research, Ġnejna Bay, Mistra Bay and Qrajten Point. What was done to create such a table is to take the mean data of each variable both summer and winter. The following step was that the highest value for each season variable between the three bays under discussion was given a number value of ‘1’ while the lowest was given a ‘3’.The value between these two extremities was assigned a value of ‘2’. Some data evaluation such as human influence is based upon the author’s research and observations and therefore may differ according to who may be analyzing this research.

Data Evaluation

Ġnejna

Mistra

Il-Qraten Point

Summer

Winter

Summer

Winter

Summer

Winter

Actual Length of Beach

1

2

3

Area

2

3

1

1

3

2

Cailleux Roundness

2

3

3

1

2

2

Cailleux Flatness

2

3

3

2

1

1

Fetch

2

3

1

Folk and Sneed Sphericity

2

1

1

2

3

3

Infiltration Rate***

3

3

2

2

1

1

Beach Length

2

3

1

1

3

2

Longshore Drift

2

2

3

3

1

1

Maximum Projection

2

2

3

3

1

1

Morphological Index

2

3

3

2

1

1

Overall Depth of Water

2

3

3

1

1

2

Scenery*

1

2

3

Scheiderhohn Elongation

1

1

2

2

3

3

Seasonal Change

3

2

1

Sediment Collected

2

1

3

Sediment Size

1

2

3

3

2

1

Slope Ratio

2

3

1

Ouma Roundness

2

3

3

2

1

1

Volume

2

3

3

2

1

1

Wadell Roundness

1

1

3

2

2

3

Width

2

3

1

1

3

2

Wind Influence

1

3

2

Accessibility*

2

3

1

Bathing Water Quality **

1

3

1

Human Influence*

3

2

1

Litter (by humans)*

3

1

2

3

1

2

People Visiting*

1

3

2

Table 5.3: A summary of all the data collected in this dissertation and comparing them between the three bays.

* Based upon the author’s research and observations.

**Data taken from the 2006 Annual Report on Bathing Water Quality produced by the Malta Department of Public Health.

***Infiltration Rate taken according to the fastest in time at 0ml.

Table 5.3 is excellent in comparing the three bays between one another and identifying which one is more influenced by a physical factor than another. It gives a broader view of how the characteristics analyzed and chosen for this dissertation are influential both upon one another and between bays. Ġnejna Bay has the lowest infiltration rate and seasonal change but it has the highest wind influence and shingle elongation. Mistra Bay, on the other hand, has the lowest wind influence together with its fetch, longshore drift, slope profile sediment size and maximum projection. It has the highest shingle beach length and width in this dissertation as well as the highest amount of sediment collected. Qrajten Point has the highest fetch and longshore drift from the three bays together with its slope ratio, infiltration rate and sediment change whilst at the same time having the lowest number of sediment collected.  

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