**4. Case study-2: Coastal erosion problem in Side, Perissia Hotel Beach**

The second example for the adverse effects of anthropogenic activities on geomorphological evolution of coastal areas is from one of the touristic areas of Turkey; Perissia Hotel Beach, located in Side in Antalya at southern coasts of Turkey (Fig. 7). Side is one of the resort towns in Antalya, heavily utilized by touristic activities with numerous hotels. The closest rivers to Side are the Manavgat River (at 93 km in length, app. 12.5 km to Perissia Hotel Beach) and Köprü Çay stream, one of the finest rafting sites in Mediterranean region (at 14 km in length, app. 19 km to Perissia Hotel Beach). There are two dams on the Manavgat River; Oymapnar (1984) and Manavgat (1987) dams. The Manavgat River drains a

Measured 18.04.2003 Measured 08.02.2007 Computed 2007, CSIM

800 1200 1600 2000 2400 2800 3200 3600 4000 4400

**Alongshore Distance, x (m)**

Fig. 6. Comparison of the site measurements with the numerical simulation (Groin series

In the design of coastal defense structures such as shore perpendicular groins as in the case of the Kzlrmak River mouth, adverse effects of the defense structures at the adjacent shores have to be studied before the implementation of the project. In this case study, as an application of the numerical model, the shoreline changes both between coastal defense

Fig.6 shows that the shoreline changes between groins could only be simulated qualitatively; yet, the shoreline retreat after Groin-8 is in good agreement with the measurement quantitatively. For the groin system, the numerical model results reflect the shoreline changes qualitatively but not quantitatively. A reason for the inconsistency between the measured and computed shoreline positions for the year 2007 at the groin series might be due to the actual bypassing amount of sediment from the first 2 Y-type and 1 Itype groin system is not well defined. Also the small amount of the sediment carried by the river is neglected in the computations as no reliable knowledge or measurements regarding the amount of sediment carried by the river exist. As for the downstream shore adjacent to Groin-8, the agreement between the numerical model results and measurements are in good

**4. Case study-2: Coastal erosion problem in Side, Perissia Hotel Beach** 

The second example for the adverse effects of anthropogenic activities on geomorphological evolution of coastal areas is from one of the touristic areas of Turkey; Perissia Hotel Beach, located in Side in Antalya at southern coasts of Turkey (Fig. 7). Side is one of the resort towns in Antalya, heavily utilized by touristic activities with numerous hotels. The closest rivers to Side are the Manavgat River (at 93 km in length, app. 12.5 km to Perissia Hotel Beach) and Köprü Çay stream, one of the finest rafting sites in Mediterranean region (at 14 km in length, app. 19 km to Perissia Hotel Beach). There are two dams on the Manavgat River; Oymapnar (1984) and Manavgat (1987) dams. The Manavgat River drains a


0

N

and downdrift of Groin-8)

Groin-5

Groin-4

Groin-6

Groin-7

**3.3 Results and discussion: Kzlrmak River mouth** 

structures and adjacent shore are studied together.

agreement both qualitatively and quantitatively.

Groin-8

100

200

**Cross-shore Distance, y (m)**

300

400

500

Groin-3

600

topographic basin of 928 km2 extending to the northern Taurus mountain range and with the addition of several closed basins (Mesozoic limestone aquifers), it has a total drainage area of 9,100 km2, one of the major catchment basins in the Mediterranean coastal area (Yurtsever & Payne, 1986). The direction of the net longshore drift is from East to West.

Fig. 7. Location of Side, Perissia Hotel beach and effective fetch distances for all directions (Google Earth, 2011)

The beach in front of Perissia Hotel is approximately 300 meters long and the width of the beach was approximately 50 meters before 1999. It is protected by naturally existing rocky formations at the east and west boundaries of the beach which extend 25 meters into the sea and a 120 meter long pier at the center of the beach, rocky formations lay underneath. The major protection for the beach against erosion due to wave attack was the rocky formations which were located at approximately 1-1.5 meter water depths and 60-100 meters offshore acting as submerged breakwaters and dissipating the energies of the approaching waves. However, the rocky formations in the western part of the beach were removed from the sea bottom in respond to customer needs in 1999. Altering the characteristics of the sea bottom topography, a serious erosion problem (retreating approximately 30 meters) was initiated at the beach mostly due to offshore movement of sands under wave action especially in winter season (Fig. 8). Remedial attempts utilizing artificial nourishment and construction of a groin of 25 meter long and 2 meter wide behind the pier could provide some amount of accretion at eastern part of the beach but did not work properly for the rest of the beach.

For the purpose of finding a consistent and effective remedial measure for the coastal erosion problem at Perissia Beach, site investigations and bathymetrical surveys were performed, wave climate of the region was determined and numerical modeling studies

Intervention of Human Activities on

and nearshore bathymetry (18.11.2006)

structures and nearshore bathymetry (18.11.2006)

• Western groin is extended to 15 meters towards the sea.

• Approximately 6000 m3 sand artificially added to the beach.

meters long groin underneath the pier was removed.

Geomorphological Evolution of Coastal Areas: Cases from Turkey 133

• Existing 25 meters long groin underneath the pier was removed for aesthetic reasons.

• The construction of the submerged offshore breakwater is delayed. The existing 25

Fig. 9. Proposed remedial measures for the shoreline erosion at Perissia Hotel Beach at Side

Fig. 10. Condition of Perissia Hotel Beach at Side at 09.01.2010, applied coastal defense

were carried out for alternative solutions by Güler et al. (2008). The wave climate of the region was determined carrying out a wave hindcasting study using the hourly average wind data measured by the nearest coastal meteorological station (Alanya Meteorological Station) for the years 1993-2004 which is obtained from DMİGM. The dominant wave directions were found to be South-South-East, South and South-South-West directions. Alternative solutions for the coastal erosion problem including hard and soft measures were discussed in detail in view of effectiveness.

Fig. 8. Perissia Hotel Beach at Side; shoreline retreat due to erosion over the years, red line shows the shoreline position approximately in August, 2006 (a: view of the western part of the beach from sea, b: view of the eastern part of the beach from sea; pictures from 1999; Güler et al., 2008)

The coastal protection system proposed was composed of several measures including both hard and soft measures, considering geomorphological features of the beach, sediment trapping capacity, possible harm to neighboring beaches and also scenic beauty. It was planned to be applied in three stages. The first stage is the construction of a 40 meters groin, 15 meters of which is at the land part, at the western border of the beach in addition to the existing groin at the mid-beach. This groin was planned to be a low crested structure, which will be at mean sea level at high tides and during storm events. It was actually planned to use the existing rocky formation at the western edge of the beach and strengthen it up to 25 meters seaward from the beach. The second stage includes the construction of a 40 meters submerged breakwater which is 30 meters away from pier and 60 meters offshore at the western part of the pier with a crest height 1 meter below still water level. The final stage was the nourishment of the western part of the beach between to groins (one existing and one constructed) at least 30 meters from the shoreline having a median grain size of around 1 mm (approximately 7000 m3 of sand). It was left optional to utilize gabion structures in front of the nourished area against wave action in cross-shore direction. The median grain size diameter (D50) was found as 0.15 millimeters from the sieve analyses of the sediment samples taken from the site (Ergin et al., 2006). The summary of the proposed solution is shown in Fig. 9.

A recent site investigation was performed in January, 2010. Applied measures are investigated and the current shoreline position was measured. During the site investigation, it is found that the implemented remedial measures differ than the proposed coastal defense system presented above slightly in dimension and construction sequence:

were carried out for alternative solutions by Güler et al. (2008). The wave climate of the region was determined carrying out a wave hindcasting study using the hourly average wind data measured by the nearest coastal meteorological station (Alanya Meteorological Station) for the years 1993-2004 which is obtained from DMİGM. The dominant wave directions were found to be South-South-East, South and South-South-West directions. Alternative solutions for the coastal erosion problem including hard and soft measures were

**(a) (b)** 

N

Fig. 8. Perissia Hotel Beach at Side; shoreline retreat due to erosion over the years, red line shows the shoreline position approximately in August, 2006 (a: view of the western part of the beach from sea, b: view of the eastern part of the beach from sea; pictures from 1999;

N

The coastal protection system proposed was composed of several measures including both hard and soft measures, considering geomorphological features of the beach, sediment trapping capacity, possible harm to neighboring beaches and also scenic beauty. It was planned to be applied in three stages. The first stage is the construction of a 40 meters groin, 15 meters of which is at the land part, at the western border of the beach in addition to the existing groin at the mid-beach. This groin was planned to be a low crested structure, which will be at mean sea level at high tides and during storm events. It was actually planned to use the existing rocky formation at the western edge of the beach and strengthen it up to 25 meters seaward from the beach. The second stage includes the construction of a 40 meters submerged breakwater which is 30 meters away from pier and 60 meters offshore at the western part of the pier with a crest height 1 meter below still water level. The final stage was the nourishment of the western part of the beach between to groins (one existing and one constructed) at least 30 meters from the shoreline having a median grain size of around 1 mm (approximately 7000 m3 of sand). It was left optional to utilize gabion structures in front of the nourished area against wave action in cross-shore direction. The median grain size diameter (D50) was found as 0.15 millimeters from the sieve analyses of the sediment samples taken from the site (Ergin et al., 2006). The summary of the proposed solution is

A recent site investigation was performed in January, 2010. Applied measures are investigated and the current shoreline position was measured. During the site investigation, it is found that the implemented remedial measures differ than the proposed coastal defense

system presented above slightly in dimension and construction sequence:

discussed in detail in view of effectiveness.

Güler et al., 2008)

shown in Fig. 9.


Fig. 9. Proposed remedial measures for the shoreline erosion at Perissia Hotel Beach at Side and nearshore bathymetry (18.11.2006)

Fig. 10. Condition of Perissia Hotel Beach at Side at 09.01.2010, applied coastal defense structures and nearshore bathymetry (18.11.2006)

Intervention of Human Activities on

wave height in at the toe of the structure.

are disregarded in the computations.

meters long groin underneath the pier.

dates 18.11.2006 and 09.01.2010 are given in Fig. 11.

**4.3 Results and discussion: Side, Perissia Hotel Beach** 

Geomorphological Evolution of Coastal Areas: Cases from Turkey 135

For the numerical modeling of the applied coastal defense measure system, the shoreline at western part of the beach is assumed to be nourished till the end of the newly constructed groin at land side which makes approximately 5600 m2 of nourishment area. It is assumed that the shoreline remained same till the construction of the western groin. The length of the western groin is 52 meters from the nourished shoreline of 2008. The rocky formations shown in Fig. 9 and 10 are modeled as submerged offshore breakwaters at various crest heights, widths and distances from shoreline. Submerged breakwaters or such rocky formations close to still water level force the waves to break and dissipate their energies and create sheltered wave fields behind the formations. The wave heights behind such structures are computed using diffraction terms and transmission coefficients (Ct=Ht/Hi, ratio of transmitted wave height to incoming wave height) in CSIM. Depending on geometrical properties of the rocky formations given in the bathymetry measured in 18.11.2006, the transmission coefficients are roughly computed using below given equation (CIRIA, CUR, CETMEF, 2007) where Rc is the crest height from still water level and Hs is the significant

The berm height (B), the landward end of the active profile, is assumed as 1.5 meters according to the site investigations. The sequence of wave data input (Table 2) in the simulation starts from W to SE directions for each year. For the calibration of the numerical model, the shoreline

Alpar et al. (1995) gives a 0.21 meters spring range of semi-diurnal tidal variations together with a seasonal variation of 0.18 meters sea level variations for Antalya based on sea level measurements of Antalya station for the years 1935-1976. The effects of sea level variations

The computed position of shoreline using CSIM and measured shoreline positions for the

As seen from Fig. 11, the shoreline change computed by the numerical model in the eastern part of the beach is in agreement with the measured shoreline both qualitatively and quantitatively. The erosion at the eastern part of the beach is due to the removal of the 25

For the western part of the beach, the shoreline changes are in agreement qualitatively but not quantitatively. The accretion and erosion at the toe of the groin both on the eastern and western sides are in very good agreement with the measured shoreline in 2010 both qualitatively and quantitatively. The main reason for the quantitative disagreement between measured and computed results for the western part of the beach is due to disregarding the cross-shore sediment transport in the computations. In this area, which is bounded with the pier and the groin, the cross-shore sediment transport appears to be more effective and has to be included in the computations at the further stages of investigations. The excessive erosion in the western part of the beach could be reduced with the construction of the proposed submerged offshore breakwater (Fig. 9) which will reduce the cross-shore sediment transport.

retreat after the construction of the groin till January, 2010 has been used.

C 0.46 0.3R /H <sup>t</sup> = − c s for -1.13 < Rc/Hs < 1.2 (9)

**4.2 Numerical modeling study: Side, Perissia Hotel Beach** 

The implemented remedial structures and condition of the beach during the site investigation are shown in Fig. 10. In this study, the implemented measures are discussed and shoreline changes between the years 2006-2010 are studied with one-dimensional numerical shoreline change model, CSIM.

#### **4.1 Wave climate study: Side, Perissia Hotel Beach**

To obtain the wave climate in the last ten years at Side, a wave hindcasting study is performed using the using hourly average wind data measured at 10 m above ground level by Alanya Meteorological Station between the years 1993-2004, obtained from DMİGM. For each direction, the effective fetch distances are determined for each direction with an effective generation area as a sector from -22.5° to +22.5° totally covering an area of 45° with 7.5° intervals, from South-East to West using the navigation maps of SHODB. The effective fetch directions and the effective fetch distances are shown in Fig. 7.

Using the effective fetch distances and the wind data obtained from Alanya Coastal Meteorological Station, deep water wave parameters (Hs0 : deep water significant wave height, Ts : significant wave period) are obtained for the storms occurred during 12 years (1993-2004) by using the numerical model, W61, developed at Middle East Technical University, Department of Civil Engineering, Ocean Engineering Research Center. The characteristic deep water wave steepness value (Hs0/L0) for the project area is obtained as 0.042 from deep water significant wave heights and deep water wave lengths computed from corresponding significant wave periods of each individual storm.

The wave conditions in Mediterranean Sea are moderate compared to the Black Sea. There is not a very significant difference between the wave characteristics and their occurrences between the seasons. Therefore, for Side, an annual based wave data input sequence is prepared for the numerical model to carry out long term wave statistics and determination of representative deep water significant wave characteristics for each direction. The wave data input for the model consisting of representative wave heights, corresponding periods and annual frequencies for all directions are presented in Table 2.


Table 2. Representative wave conditions and annual occurrence durations for all directions (Güler et al., 2008)

The implemented remedial structures and condition of the beach during the site investigation are shown in Fig. 10. In this study, the implemented measures are discussed and shoreline changes between the years 2006-2010 are studied with one-dimensional

To obtain the wave climate in the last ten years at Side, a wave hindcasting study is performed using the using hourly average wind data measured at 10 m above ground level by Alanya Meteorological Station between the years 1993-2004, obtained from DMİGM. For each direction, the effective fetch distances are determined for each direction with an effective generation area as a sector from -22.5° to +22.5° totally covering an area of 45° with 7.5° intervals, from South-East to West using the navigation maps of SHODB. The effective

Using the effective fetch distances and the wind data obtained from Alanya Coastal Meteorological Station, deep water wave parameters (Hs0 : deep water significant wave height, Ts : significant wave period) are obtained for the storms occurred during 12 years (1993-2004) by using the numerical model, W61, developed at Middle East Technical University, Department of Civil Engineering, Ocean Engineering Research Center. The characteristic deep water wave steepness value (Hs0/L0) for the project area is obtained as 0.042 from deep water significant wave heights and deep water wave lengths computed

The wave conditions in Mediterranean Sea are moderate compared to the Black Sea. There is not a very significant difference between the wave characteristics and their occurrences between the seasons. Therefore, for Side, an annual based wave data input sequence is prepared for the numerical model to carry out long term wave statistics and determination of representative deep water significant wave characteristics for each direction. The wave data input for the model consisting of representative wave heights, corresponding periods

**(m)** 

Table 2. Representative wave conditions and annual occurrence durations for all directions

**W** 0.77 3.42 11 **WSW** 0.84 3.59 119 **SW** 0.88 3.67 53 **SSW** 1.01 3.93 137 **S** 0.97 3.84 229 **SSE** 1.04 3.99 26 **SE** 0.88 3.67 4

**Ts (sec)** 

**Δt (hrs)** 

numerical shoreline change model, CSIM.

**4.1 Wave climate study: Side, Perissia Hotel Beach** 

fetch directions and the effective fetch distances are shown in Fig. 7.

from corresponding significant wave periods of each individual storm.

and annual frequencies for all directions are presented in Table 2.

(Güler et al., 2008)

**Directions Hrs,0**

#### **4.2 Numerical modeling study: Side, Perissia Hotel Beach**

For the numerical modeling of the applied coastal defense measure system, the shoreline at western part of the beach is assumed to be nourished till the end of the newly constructed groin at land side which makes approximately 5600 m2 of nourishment area. It is assumed that the shoreline remained same till the construction of the western groin. The length of the western groin is 52 meters from the nourished shoreline of 2008. The rocky formations shown in Fig. 9 and 10 are modeled as submerged offshore breakwaters at various crest heights, widths and distances from shoreline. Submerged breakwaters or such rocky formations close to still water level force the waves to break and dissipate their energies and create sheltered wave fields behind the formations. The wave heights behind such structures are computed using diffraction terms and transmission coefficients (Ct=Ht/Hi, ratio of transmitted wave height to incoming wave height) in CSIM. Depending on geometrical properties of the rocky formations given in the bathymetry measured in 18.11.2006, the transmission coefficients are roughly computed using below given equation (CIRIA, CUR, CETMEF, 2007) where Rc is the crest height from still water level and Hs is the significant wave height in at the toe of the structure.

$$\mathbf{C\_{t}} = 0.46 - 0.3 \mathbf{R\_{c}/H\_{s}} \quad \text{ for -1.13} \le \mathbf{R\_{c}/H\_{s}} \le 1.2 \tag{9}$$

The berm height (B), the landward end of the active profile, is assumed as 1.5 meters according to the site investigations. The sequence of wave data input (Table 2) in the simulation starts from W to SE directions for each year. For the calibration of the numerical model, the shoreline retreat after the construction of the groin till January, 2010 has been used.

Alpar et al. (1995) gives a 0.21 meters spring range of semi-diurnal tidal variations together with a seasonal variation of 0.18 meters sea level variations for Antalya based on sea level measurements of Antalya station for the years 1935-1976. The effects of sea level variations are disregarded in the computations.

The computed position of shoreline using CSIM and measured shoreline positions for the dates 18.11.2006 and 09.01.2010 are given in Fig. 11.

#### **4.3 Results and discussion: Side, Perissia Hotel Beach**

As seen from Fig. 11, the shoreline change computed by the numerical model in the eastern part of the beach is in agreement with the measured shoreline both qualitatively and quantitatively. The erosion at the eastern part of the beach is due to the removal of the 25 meters long groin underneath the pier.

For the western part of the beach, the shoreline changes are in agreement qualitatively but not quantitatively. The accretion and erosion at the toe of the groin both on the eastern and western sides are in very good agreement with the measured shoreline in 2010 both qualitatively and quantitatively. The main reason for the quantitative disagreement between measured and computed results for the western part of the beach is due to disregarding the cross-shore sediment transport in the computations. In this area, which is bounded with the pier and the groin, the cross-shore sediment transport appears to be more effective and has to be included in the computations at the further stages of investigations. The excessive erosion in the western part of the beach could be reduced with the construction of the proposed submerged offshore breakwater (Fig. 9) which will reduce the cross-shore sediment transport.

Intervention of Human Activities on

**5. Conclusion** 

activities at coastal areas.

**6. Acknowledgements** 

**7. References** 

pp.58–63

such as submerged offshore breakwater.

Geomorphological Evolution of Coastal Areas: Cases from Turkey 137

panoramic views of the beach at two different dates are given. The restoration of the western part of the shoreline is clearly seen in these pictures. However, the shoreline in eastern part started to retreat in return due to the removal of the groin underneath the pier. This retreat may be controlled by the implementation of the proposed remedial structures

In this chapter, governing parameters of the geomorphological evolution of the coastal areas are briefly discussed in the view of sediment budget concept. Numerical modeling of the sediment transport mechanisms in coastal areas is discussed putting emphasis on onedimensional numerical modeling which has been used as an effective tool by scientists and engineers for years to understand and predict shoreline changes in long term due to coastal erosion problems. In the case studies given above, the general approach for predicting shoreline changes at coastal areas, where human induced coastal erosion has become a chronic problem, is discussed. The Kzlrmak River mouth is a typical example of the effects of flow regulation structures on rivers and wetlands of alluvial plains fed by these rivers and resulting in severe coastal erosion problems in return. While silting of the reservoirs decreases the economic life of them, the coastal areas at downstream of these reservoirs hunger the silted material and degrades day by day. Perissia beach case is again another typical example of direct human intervention on the geomorphological and coastalhydrodynamic processes at the beaches and resulting in erosion problems. These two cases stress the importance of the sustainable use of the resources in the long term for the benefit of mankind and of developing more sophisticated tools and methodologies to provide a better understanding and prediction capabilities of the adverse effects of anthropogenic

The authors are thankful to General Directorate of State Hydraulic Works (DSİGM) and Bafra Plain Irrigation Project Directorate of DSİ for providing shoreline measurements of the Kzlrmak River mouth, to General Directorate of Meteorological Affairs (DMİGM) for providing wind data of Sinop and Alanya Meteorological Stations, to Navigation, Hydrography and Oceanography Department of Turkish Naval Forces (SHODB) for providing navigational maps used in computations. The authors also would like to thank to Prof.Dr. Ahmet Cevdet Yalçner, Dr. Ilgar Şafak, Salih Serkan Artagan and Mustafa Esen for

Alpar, B., (2009). *Vulnerability of Turkish coasts to accelerated sea-level rise*, Geomorphology 107,

Alpar, B., Doğan, E. & Yüce, H., (1995), "On the long term (1935-1976) fluctuations of the

Antalya", Turkish Journal of Marine Sciences, Vol.1, pp.13-22

low frequency and main tidal constituents and their stability in the Gulf of

their efforts and supports in various stages of the above given studies.

Fig. 11. Perissia Hotel Beach at Side; shoreline retreat due to erosion over the years, red line shows

Fig. 12. Two panoramic views of the Perissia Hotel Beach at 26.07.2006 and 09.01.2010 showing the before and after remedial measures

The coastal erosion problem faced with in Perissia Hotel Beach is a very important example of the erosion caused by alteration and harming of the natural balance in a coastal area, which results from damaging and removing the rocky formations, naturally acting as submerged breakwaters or reefs and thus, protecting the beach against wave action. Such an application has initiated and accelerated the erosion at Perissia Hotel Beach. In Fig. 12, the panoramic views of the beach at two different dates are given. The restoration of the western part of the shoreline is clearly seen in these pictures. However, the shoreline in eastern part started to retreat in return due to the removal of the groin underneath the pier. This retreat may be controlled by the implementation of the proposed remedial structures such as submerged offshore breakwater.
