Egypt northern coast
Egypt northern coast Development, Cases Abstract: The Northwestern coast of Egypt extends for 520 km along the Mediterranean Sea west of Alexandria city.
The special characteristics of this area have made it very attractive for tourists and entertainment activities.
However, the beaches along the coast are not fully suitable for recreational activities due to some of their physical and morphological characteristics.
This situation leads to unsupervised construction of artificial coastal measures along different parts
of the coast.
Most of these works have negative impacts on the coast.
Egypt northern coastThe available satellite images within the last ten years as well as field survey were used to evaluate the shoreline changes under the effect of artificial structures, identify the coastal problems, summarize the research efforts to reach the sustainable development, and specify the required research for the future. The coast can be divided into two main parts, undeveloped and developed.
The undeveloped areas are divided into flood affected and flood-unaffected areas while the developed areas represent the major towns along the coast.
Monitoring of the undeveloped areas shows that it has dynamically stable shorelines.
On the other hand, observing the developed areas reveal that the coastal structure along these areas have a significant impact on the shorelines.
The study identifies three substantial challenges and recommends the solution trend for each challenge.
Firstly, the sustainable development of the undeveloped areas.
The morphological features can be used to control the land use to reach the sustainable development.
Secondly, recreational resorts problems, which divided into two categories, one within dynamically stable beaches and the other within unstable beaches.
A Suspended Breakwater on piles is recommended to be used for the first category, while a combination of hard and soft solutions, such as a perched beach, can work for the second one.
The third challenge is the human interference within the developed areas, which can be solved case by case in the integrated manner.
Keywords:
Coastal Structures; Egypt northen coast; Satellite Images; Shoreline Changes; Sustainable
Development
Egypt northern coast
Egypt northern coast
1. INTRODUCTION
The shoreline is one of the rapidly changing features of the coastal zone that is dynamic in nature.
It is also one of the earlier features react to any changes in the coastal area.
Analysis of the shoreline changes is fundamental to a broad range of investigations undertaken by coastal scientists, oceanographers, coastal engineers, and coastal managers [1, 2].
Shoreline information is used in designing the coastal protection, calibrating and verifying numerical models, assessing sea-level rise, developing hazard zones, and formulating policies to regulate coastal development.
Shoreline changes can be investigated by using field data measurements or satellite images.
Satellite data of high resolution at small intervals and short spaced transect can accurately predict the shoreline changes with cost efficiency.
Egypt northen coast is bounded by the Libyan border from the west and El-Agami
headland, west of Alexandria, from the east with a total length of about 520 km, Figure 1.
The beaches along the coast are distinct by white Oolitic carbonate sand, clear blue water, mild weather, and the sun prevailing most of the year.
All these privileges have made these beaches attractive sites for tourists and entertainment activities.
During the last three decades, more than two hundred recreational villages have been constructed in this area.
There is no severe natural coastal erosion problem along this coastal zone.
However, the beaches are not suitable for swimming due to the steep slope of their surf zone and the generation of rip currents that cause several troubles and serious hazards to the swimmers.
This situation enforced village owners to build coastal structures or construct artificial swimming pools and/or lagoons connected to the sea in order to create suitable and safe places for swimming activities.
These coastal schemes were built in the form of inlets to coastal lagoons (El-Alamien Marina center jetties, and SidiKerair coastal resort breakwater), and protected swimming areas (Marabella and Six of October resort village breakwaters).
Most of these schemes have a noticeable impact on the beaches in form of coastal pollution, accretion and/or erosion.
Egypt northern coastSeveral investigators have studied these coastal problems and they have concluded that the insufficient local data and the misunderstanding of the prevailing coastal processes were the main reasons for the poor design of these coastal schemes [3–9].
The aim of this work is to evaluate the shoreline changes under the effects of coastal structures compared to the natural behavior within the study area, identify the coastal problems, summarize the previous research efforts to reach the sustainable development and specify the required research for the future.
2 Beach Behavior and Impact of Coastal Structures on the Sustainable Development, Cases from the Northwestern Coast of Egypt
2. MATERIAL AND METHODS
Due to the lack of data, the available satellite images from Google Earth within the last ten years were used in this study.
First, the Digital Globe images of about 15-30 m resolution were downloaded and imported to the Geographical Information System, ArcGIS, software.
Before analysis, the images were corrected for distortion and then adjusted to the correct scale using ground control points such as coastal structures, famous buildings.. etc.
Second, in order to detect temporal changes, the shoreline (line of the high water level) for each coastal zone was digitized manually and visually throughout different years.
Finally, the different shorelines within each location were compared and the average rate of hanges
(erosion or accretion) were calculated.
To verify this method, field measurements for the shoreline were executed at El Ahlam resort, east of Marina, by using Differential Global Positioning System (DGPS) during January 2013, Figure 2.
The image of the same area and the same period was downloaded from Google Earth and the shoreline was digitized with the same methodology described above.
The shoreline of 700 m length was divided into segments of 20 m and the standard error for each segment was then calculated relative to in situ DGPS measurements.
The average error was 1.85 m with standard deviation
1.26 m.
3. RESULT AND DISCUSSION
3.1 Shoreline Evolution in the Northwestern Coast The Northwestern coast of Egypt can be divided into two main parts according to human activities.
Developed areas (30% of the total coastline extend) which have enormous change in natural conditions by changing the terrace morphology (filling and excavation), executing many concrete structures, changing the species of the natural vegetation, degrading the natural recourses especially the fresh water resource, and constructing coastal protection works which change the stability of the coastal zone.
The second part is the undeveloped areas that divided into two parts; flood drainage-affected areas (27 % of the total coastline extend) where most of the watershed discharge their water to the Mediterranean Sea, and flood drainage-unaffected areas (43% of the total coastline extend).
A typical example of the flood drainage-unaffected areas is located 50 km west of Marina El-Alamien undeveloped and by taking a closer look, it is clear that throughout years from 2005 to 2011, the shoreline has a dynamic stability with very small local variation of about +/-1.0 m from year to year, Figure 3.
Also field observations shows that there are a shoreline fluctuation from season to season due to the coastal hydrodynamic forces.
This fluctuation may give a false estimation of shoreline change in some places.
The flood drainage-affected area extends for about 140 km in the western side of the study area between Matrouh and El Salloum.
The rainfall in the northwestern coast ranges between 105.0 mm/year at El Salloum and 199.6 mm/year at Alexandria.
The estimated sediment deposit to the sea from the flood area ranges between 0.8 and 5.3 ton/hectare/year [10]. A typical area represent this kind of beach is located 26 kilometers east of SidiBarrani city, Figure 1 & Figure 4.
Its coastal zone has a series of high-elevated ridges parallel to the shoreline, and during a specific time of the year, this coastal ridge receives a lot of fresh water through storm rains.
These amounts of water and its eroding sediment drive their way down to the Mediterranean Sea through the drainage system.
The shoreline changes during the period from 2009 to 2013, show that the area is stable.
This stability may be related to two main factors; first, the shoreline of the area almost composed of carbonate rocks, which represent a natural defensive structure against currents and waves energies.
Second, since the area is undeveloped and no structure measures have been implemented in it, the amount of sediment transported into the area is almost equal to the amount of sediment transported out of it. Furthermore, the sediment transported to the sea during the flood season
may have a specific role in this stability.
Egypt northern coastThe developed areas within the northwestern coast of Egypt are extending for about 150 km. Many coastal structures have been constructed within these areas to provide more suitable touristic environment.
The side effects of the coastal protections and the corresponding coastal behavior according to shoreline modifications can be summarized as follow;
1. Marina El-Alamien large-scale recreational summer resort is one of the most rapidly developing
areas on the northwestern coast of Egypt.
It is located 94 km west of Alexandria city, Figure
1. The resort was built around an artificial lagoon, which has been connected to the sea through
{google_map}EgyptAlexandria Matrouh{/google_map}
four dredged channels.
Five jetties perpendicular to the shoreline of lengths varied from 350 to
1250 m have been constructed in the period from 1989 to 1993.
During the period from 2002 to 2003, additional eight short groins of lengths varied from 150 to 400 m, with in between artificial nourishment, have been implemented in the space between the outlets of the artificial lagoon to overcome the resulted erosion problem from the first group of structures [9], Figure 5.
The shoreline variations during the period from 2007 to 2012 shows a continuous accretion west of the first groin westward, which causes sand bypass and a sedimentation in the downstream of the groin with net rate of 18 m/year, Figure 5.
The rest of the area suffers from relatively small rate of erosion in the structures-downstream and accretion in their upstream sides.
The highest erosion rate occurs downstream of the last inlet eastward.
2. Marabella resort is located 70 km west of Alexandria city, Figure 1.
It is located in an open active area exposed to waves and currents.
The coastal area of Marabella resort is characterized by rip currents and steep slope in the near-shore zone causing several troubles and serious hazards to the swimmers.
Four detached breakwaters were constructed along the beach between 1991 & 1992,
Figure 6.
Since the detached breakwaters function is to reduce the amount of wave energy, the
long-shore sediment is accumulated in the shadow zones of the breakwaters and salients are formed behind the first three breakwaters westward.
Also an erosion problem appears east of the resort in front of Suez Canal Village.
These salients are dredged yearly and transported eastward in order to eliminate the erosion problem of Suez Canal village shoreline.
Shoreline changes of Marbella resort was studied from 2004 to 2013 and the results revealed that sedimentation in the shadow Beach Behavior and Impact of Coastal Structures on the Sustainable Development, Cases from the Northwestern Coast of Egypt
3. Sidi-Kerir is a summer resort located at about 33 kilometer west of Alexandria, It is suffering from the steep slope beaches and rip currents that prevent residents from enjoying swimming in the sea.
In 1988, an artificial lagoon connected to the sea was constructed in the middle part of backshore area, to provide safe swimming places and areas for water sports.
The length of the lake is about 600 m with an average width of about 100 m and maximum water depth of 3.0 m. The water circulation inside the lagoon was established by a feeding water pipe
intake at its western border while the drained water was carried out by a pumping station on its
eastern side.
However, some hydraulic and hygienic problems have been resulted in the area.
In 1993, a detached breakwater has been constructed in the sea in front of the lagoon. Shortly after its execution, sedimentation, erosion and pollution problems have been resulted.
Accordingly, some solutions have been attempted during the period from 1993 to 2005 to improve the situation of the lagoon and allow the residents to enjoy their stay in the village, but they failed to make the required improvements in the water conditions.
Observing SidiKerir shoreline throughout years 2004 to 2009 shows that the entire shoreline suffers mainly from erosion problem with higher erosion rate east of the lagoon inlet with rates (3.2 – 5.2 m/year) .
This situation changed to slit accretion during the period from 2009 to 2013 where the shoreline modified to reach a new
condition of stability. Egypt northern coast
4. El-Agami protection project is located 20 km west of Alexandria city.
It is bounded by West Nobarya drain westward and the eastern border of the sixth of October village resort eastward with a total length of about 2.0 km, There is a rocky ridge extending parallel to the shoreline.
The distance of the ridge from the shoreline ranges from 600 to 1200m.
Seven detached breakwaters have been constructed to provide safe and secure environment in the area, Figure 8.
Breakwaters were constructed during the period from 1998 to 2003 at a distance of about 200 m
from the original shoreline and in a water depth between 4 and 5 m. Each breakwater unit is 100 m
long with gap spacing of 50 m.
A temporary small harbor was built to the west of these breakwaters
to facilitate their construction.
Deposition of sea grass and an undesirable sedimentation were parts of the coastal area problems.
Accordingly, a decision was made to remove the temporary harbor.
Removing the harbor improves the ecosystem of the area just behind the western breakwater
by clearing out and stopping the deposition of the sea grass in this area with its negative effects
on beach conditions.
Continuous observation of El Agami shoreline throughout the period from June-2004 to April-2013 showed that, the shoreline west of Nobarya drain and eastward of 6
Beach Behavior and Impact of Coastal Structures on the Sustainable Development, Cases from the Egypt northen coast Figure 7.
Shoreline changes at SidiKerir resort village, North western coast.
Shoreline changes at El Agami resort village, north western coast of Egypt.
it until the beginning of the breakwaters shows a noticeable accretion with rates ranges from (0.5
to 3 m/year).
However, the area behind the breakers (shadow zone) is experiencing a significant accretion(3 – 10 m/year) with a decreasing rate eastward then the situation is reversed and the area has experienced erosion with an average rate of about -2.5 m/year, The above section clarified that the coastal measures within the study area have dramatic impacts on the surrounding beaches.
Beach erosion, accretion, pollution and rip currents are some of the coastal structures related
impacts within the study area.
In addition, the shoreline behavior is changing on the seasonal scale
according to the coastal hydrodynamics, Figure 9.
The shoreline retreat is the dominated feature during winters, while summer seasons shows some sedimentation behavior. The detailed observation concluded that the study area has three main challenges;
1. The sustainable development of the undeveloped area.
2. Unsuitability of the beaches within the resort areas for recreational activities due to rip currents.
3. Negative impacts of the coastal structures.
Several research studies have been carried out on these three challenges in order to develop the
environmental conditions, and to reach the sustainable development of the study area. The following part
3.2 The Sustainable Development of the Undeveloped Area The undeveloped area on the west coast of Egypt from Alexandria to El Salloum is inconsistently changing its morphologic configuration forming a series of long-stretches with or without flood drains, headlands, bays, pocket beaches and completely naturally protected beaches.
This variability exhibit a wide range of natural sheltering of these shoreline ranges from weak to high protection depending strongly on the interactions between shoreline orientation and incident waves.
Frihy et al. [11] evaluated the coastal morphodynamics of the western Mediterranean coast of Egypt to increase recreational considerations.
The analysis was based on numerical modeling of the degree of shoreline vulnerability to hydrodynamic forces using a dataset of bathymetry, shoreline position and waves that were measured within the region.
The study provided a baseline to support shoreline management plan towards sustainability and maintaining the natural characteristics and resource capabilities of the area by dividing the area into four morph-types
1. High-energy exposed coastline such as headlands and Smooth-long coastline.
2. Moderate to high-energy semi-exposed coastline such as bays and embayment.
3. Low-energy semi-exposed coastline such as headlands leeside and pocket beaches.
4. Sheltered coastline such as naturally protected beaches.
The study recommended that the morphological features of the area can be used to control the land use.
For example, the calm waters existing in a naturally protected leeside of headlands, pocket beaches and naturally-sheltered areas can be used properly for recreational activities without protection measures.
On the other hand, the high-energy conditions at headlands tips and at open coastlines are not favorable for implementing hard structures and creating safe recreational beaches,however these areas can be used for industrial activities.
8 Beach Behavior and Impact of Coastal Structures on the Sustainable Development, Cases from the Northwestern
Egypt northern coast
Figure 10. Morphodynamic conceptual model of the coastal area between Matruh and Fuka, after Frihy et al. [11].
3.3 Recreational Resorts Problems The main problem within the resort villages is the unsuitability of their beaches for swimming due to the rip current.
This problem limits the development of the resorts and decreases the value of its units.
Resorts having this problem can be categorized into two groups; resorts with dynamically stable beaches and resorts with unstable beaches.
The first group found in areas with very limited human intervention, while the second group located near the coastal structures.
Koraimet al. [12]; Iskander [13], Iskande ret al.,[9]; Fanous and Khafagy, [14]; El sayed [15] and W.L., 2003 [16] studied and discussed this problem, and proposed different solutions.
The proposed structure for the area with very limited human intervention is the porous suspended breakwater (PSB), which consists of two rows of vertical circular piles and two sets of horizontal screens (front and rear), (CoRI [17]; Koraimet al. [12]), Figure 11.
Both, piles and screens curtains are working as a breakwater and wave dissipaters. The constructed piles remain in place, but the curtain walls can be adjusted according to the required performance. The horizontal axe of the screens is located around the mean water level under wave action to absorb significant portion of wave energy with minimum effect on sediment transport.
CoRI, 2012 [17] carried out physical modelstudy and showed that this kind of flexible structure can dissipate up to 78% of the wave energy according to the structure’s dimensions with minimum effect on the coastal area.
In addition, the structure efficiency increases with increasing wave height, which allow more wave transmission during calm condition and absorb more energy during rough sea.
These conditions will provide a suitable water circulation within the protected area with minimum blocking or obstruction of moving objects.
Furthermore, it is a kind of multiuse and refunded coastal structure.
I can be used as breakwater, loading and unloading jetty, walkways, restaurant and Aqua Park. Finally yet importantly, the expected cost of the new model is 25% less than the conventional breakwaters.
For the area of unstable beaches, Iskander et al., 2008 and Fanous& Khafagy [14] suggested a perched beach with the construction of a submerged breakwater parallel to the shoreline with or without transverse barriers perpendicular to the coastline.
Such a system would create a flat, wide and gradually sloping beaches using artificial sand nourishment bounded by the submerged breakwaters.
This protection work could reduce the combined action of waves and currents at offshore zone and thus decrease their energy and create a surf zone suitable for swimming and recreational activities. In addition, this will not interrupt the flow and will allow sediment movements by waves and currents to pass over them from one side to the other. Furthermore, this system will eliminate the formation of the rip currents by changing the bottom configuration.
3.4 The Coastal Structures Mitigation
Beaches of the Northwestern Coast of Egypt are dynamics in their morphological changes under
varying wave conditions, and are associated with hazardous rip currents, [7].
These circumstances have encouraged developers to build protection measures in the form of recreational structures (jetties, groins, and detached breakwaters) to create beaches, marinas, artificial lagoons and other related maritime facilities.
The irrational building of hard structures to form safe beaches in this region resulted in a Beach Behavior and Impact of Coastal Structures on the Sustainable Development, Cases from Egypt northern coast series of adverse impacts on the shoreline morphology, accelerating beach erosion, and degrading the recreational beach aesthetics as discussed in the first part of this study.
These problems affect the efficiency of the recreational villages and the surrounding areas, which leads to serious losses in the villages’ economic value.
Depending on the previous studies, [9, 13–16], some coastal structures are recommended to be coincident with coastal properties and problems for each case.
Iskander et al., [9] used intensive field measurements and numerical models to show that the nourishment projects east of Marina El Alamien Resort and El Ahlam Resort are not sufficient to overcome the erosion problem of this area, as a side effect of the coastal protection works.
The study concluded that, creating a sloping beach, 50:1, protected by a submerged breakwater parallel to the coast at water depth of 3-4 m is more suitable for this area.
This cell is filled with nourished sand to create the required beach.
This project is under construction at El Ahlam resort village with regular monitoring to evaluate
the efficiency and the adverse impacts of the project during the construction phase, Figure 12.
Marabella four detached breakwaters accumulate sediment in the shadow zone of the breakwaters
forming salient and cause severe erosion in the Suez Canal village eastward.
These salient are dredged yearly and transported eastward to eliminate the erosion problem of the Suez Canal village shoreline. Fanous and Khafagy [14] El sayed [15], andW.L. [16] studied the rip current problem of Maraqia resort village which is located 51 km west of Alexandria.
A perched beach project is proposed to create a safe zone for recreational purposes without affecting the coastal environment.
This technique was examined using mathematical and physical models.
The results showed that this solution could reduce the wave height by about 70 % and ensured a wide and safe area for swimmer to enjoy the sea water with very low effect on the seabed morphology.
Fanous et al. [7] carried out a study based on the lessons learned from the previous protection works, and by applying mathematical model, to propose a solution for SidiKerir resort beach and its artificial lagoon.
The solution consists of the complete removal of the ruins of the demolished breakwater and construct an offshore intake connected to a pipe leading to a pumping station fixed on the western side of the lagoon.
In addition, the existing draining/pumping station on the outlet of the lagoon could be used in combination with the erection of water fountains inside the lagoon to renew the dissolved oxygen in the lagoon water, Figure 13.
The above discussion shows that it is hard to find a specific structure suitable for the all places from an environmental standpoint.
A special study must be performed for each individual case to find the environmental characteristic of this area, the dominated hydrodynamic forces within coastal zone and specify the coastal problems and its driving forces.
Then the optimum solution could be recommended depending on how to deal with the problems, the environmental impact assessment, and the mitigation measures.
Monitoring areas around the coastal measures are essential in construction phase as well as every year after construction to identify the structure efficiency and side effect.
4. CONCLUSIONS AND RECOMMENDATIONS-Egypt northern coast
The study evaluates the coastline of 520 km length from Alexandria to El Saloum along Egypt northen coast.
Field data, satellite images as well as reviewing of the previous studies are used to identify the coastal problems, shoreline behaviors, coastal measures impacts and vulnerable areas within the study area.
A review for the previous efforts to solve the coastal problems within the study area is also covered, in addition to identifying the required future studies to be implemented for the development of Egypt northern coast.
Egypt northern coast can be divided into; developed areas (30% of the total coastline
extend) which have enormous change in natural conditions, undeveloped flood-affected areas (27 % of the total coastline extend) where most of the watershed discharge their water to the Mediterranean Sea, and undeveloped flood-unaffected areas (43% of the total coastline extend).
The undeveloped areas has a dynamically stable beaches with a shoreline seasonal fluctuation. This fluctuation may give a false estimation of shoreline movement in some places.
The main challenge within this area is to save a shoreline management plan towards sustainability and maintaining the natural characteristics and resource capabilities of the area.
This can be done by using the morphological features of the area as an indicator to control the land use.
On the other hand, the human interference within the developed areas has dramatically adverse impacts on their surrounding beaches.
Beach erosion, accretion, pollution and rip currents are some of such impacts within these areas. The main challenges of the developed areas are the unsuitability of the beaches for recreational activities due to rip currents and the side effects of the coastal structures.
Suspended breakwater of screen curtain wall supported on piles can be used to create a safe recreational area with minimum effect on sediment transport.
This structure is suitable only for the dynamically stable beaches.
While perched beach can be used for beaches suffer from erosion problem.
Detailed studies are recommended specially for the resorts with coastal structures to find the environmental characteristic of these areas, the hydrodynamic forces within coastal zone and specify the coastal problems and their main causes.
A comparison between the coastal zones behaviors within the developed and undeveloped areas is very useful in understanding the effect of human interference.
Also, it is recommended to study the effect of flood water and sediment in stabilize the shoreline within the flood zones.
In addition the effect of the control structures for the flood water on the shoreline stability.
