ANNEX 1
ENVIRONMENTAL CONDITIONS OF ISKENDERUN BAY

- General features

- Bottom Topography (see Fig. 6)

The bottom topography of the Bay varies almost linearly, increasing from 20 m in the inner part to approx. 90 m towards the mouth. The depth variation in the north-south direction is irregular and the south-eastern side of the Bay is steeper than the north-western side. In the north-western side, the bottom slope is modified by sediments from rivers and is covered by mud and clay with some admixture of sand in shallow areas (25 to 30 m). Poseidonia is also observed in the muddy areas, extensively.

- Rivers

The most important fresh-water supply into Iskenderun Bay is from the Ceyhan river, which has its discharge point near Yumurtalik Bay. There are several streams in the surrounding coastline but, because of the demands of agriculture for water, discharge rates are low. The annual average discharge of the Ceyhan river is 180 m³/sec, maximum discharge 2250 m³/sec, minumum discharge 20 m³/sec. The minumum values are observed between June and October and maximum values are observed in April.

There is one small bay and five lagoons along the west coast. (Fig. 7).

Yumurtalik Bay

Yumurtalik Bay is located along the north-western boundary of Iskenderun Bay. It is shallow with 15 meters maximum depth and 5 meters average depth. Its area is approximately 70 km². The inner part of Yumurtalik Bay is very shallow and there are some small lagoons connected to it by narrow straits. The bottom is covered with mud and clay.

Lagoon system

The Camlik Lagoon is also located in this region behind Yumurtalik Bay. It has an area of about 1.3 km² and a depth varying between 0.25 m and 1.5 m, with 0.75 m as an average. The lagoon is connected to Yumurtalik Bay through a very wide opening.

The Yelkoma Lagoon is located to the south of Yumurtalik Bay. It is connected to a small pond by a channel (4 m wide, 50 m long) which opens to Yumurtalik Bay. Surface area is about 0.64 km² and average depth is 0.3 m.

The Hurma Bogazi Lagoon is located near the Ceyhan river mouth covering an area of about 1.1 km². Average depth in the lagoon is 0.75 m. It is connected to the sea by a channel 70–80 m wide and 500 m long. This lagoon is connected to the Ceyhan river by a 4–5 m wide channel.

Figure 6. Bathymetry of Iskenderun Bay

Figure 7. Location of Major Lagoons and Deltas

Akyatan Lagoon is located near the town of Karatas. This lagoon is separated from the sea by a sand dune and has one opening to the sea by a narrow strait, 2 km long, about 150 m wide and 1.5 m deep. Surface area is 60 km² and average depth is 1.5 m. The Akyatan Lagoon receives agricultural drainage water from one drainage channel having a maximum discharge of about 36 m³/sec. Extensive use of pesticides in this area may result in pollution of the lagoon.

Tuzla lagoon is located to the west of the Akyatan Lagoon with a surface area about 1.6 km². This lagoon has a new man-made openning to the sea. The average depth is 0.8 m. There are some works to supply fresh-water to this lagoon.

The main problems in the management of the lagoons are build-up of sand at the entrance and poor fresh water intake. The state of pollution and productivity of these lagoons are not known.

Climatology

The annual air and sea temperature variation is shown in Figure 8. It is seen that the max. occurs in August-September and is about 30°C. Winter average temperatures are approximately 15°C. 52 years averaged climatological data for the Adana Meteorological Station are shown in Table 7 and average wind frequencies are plotted in Figures 9 and 10 for Iskenderun and Dörtyol. From October through to March winds at Iskenderun are predominantly from the south and southeast, while during the same months the predominant winds at Dortyol are from the west and east. During the period April-September, winds at Iskenderun are mostly from the N-NW sector, while at Dortyol they are from the W-SW sector. Speed and direction of the maximum observed winds are shown in Table 8. Strong north easterly winds, blowing down from the mountains, and strong SSE winds occur throughout the year. Westerly winds cause an increase in the rate of precipitation. Average rainfall is 1082 mm/year in Dortyol and 785 mm/year in Iskenderun.

Table 7. Main meteorological parameters for Adana 52 years average

(a) Precipitation in Adana

(b) Air Temperature in Adana

(c) Average Hours of Sunshine in Adana

(d) Average number of days in Frost in Adana

- Hydrography

Hydrographical features of Iskenderun Bay were investigated by the Institute of Marine Sciences of the Middle East Technical University between 1981 and 1984. The observed range of temperature, salinity, dissolved oxygen and pH are shown in Table 9.

Figure 8. Monthly average air and sea water temperatures in Iskenderun Bay (1967)

ISKENDERUN (36° 37'N, 36° 07'E)

Figure 9. Percent frequency of wind direction. Based on 22 years of observations between 1939–1979.

DÖRTYOL (36°53'N, 36°10'E)

Figure 10. Percent frequency of wind direction. Based on 22 years of observations between 1929–1970.

Table 8. Speed (m/sec) and direction of the maximum observed wind.

Note: Speed value for Yumurtalik and Uluçinar has been converted from Beaufort number to m/sec and rounded off to meters. (Ref 1)

Table 9

As is shown in Fig. 11, the temperature of the Bay water undergoes considerable variations throughout the year. The sea surface temperature of the whole water column starts to decrease in autumn and minumum sea surface temperature occur in February and extends to the bottom layers. Variations of salinity in some parts of the Bay are shown in Figure 12. Salinity increases during the November-February period and in August due to surface evaporation. The surface salinity decreases to 38.5 ppt due to rainfall and discharges from rivers.

- Circulation

Two main types of circulation are observed in the Bay. In the summer, waters coming from the Syrian coast enter the Bay near Karatas and two gyres, a clockwise one in the inner part and an anti-clockwise one in the outer part, are formed (Fig. 13). This surface circulation pattern is also observed visually from large collections of plastic materials at the centres of the gyres.

Ceyhan river inputs are transported towards the inner sections by the westerly winds which predominate in summer months. The inner part of the Bay is occupied by less saline and warmer surface waters. (Fig 14).

The cellular circulation system found within the Bay during the summer months starts to break down in autumn. During the winter season, open sea waters enter the bay near Akinci Burnu and move further towards the innermost areas along the southern coast. The waters curl eventually in a counter-clockwise direction and leave the bay near the Karatas region (Fig. 15). Less saline and cooler waters are observed in the inner part of the Bay (Fig. 16). Measurements by the Institute of Marine Sciences indicate that the average current speed is 15 cm/sec along the coastline of the Bay.

Waves

Wave height is measured at the Turkish Petroleum Company loading/ unloading quay at Dortyol. Data for 1981 indicate that wave heights of 3 m occurred throughout the year and that, during storms in January, March, November and December, wave heights reached 5 m. The duration of storms was between 3 to 5 days.

Figure 11. Vertical distribution of temperature in the middle of the Bay

Figure 12. Annual variation of salinity in Iskenderun Bay Iyiduvar, 1986)

1. Mouth of the Bay
2. Middle of the Bay

3. Inner part of the Bay
4. At Iskenderun

Figure 13. Summer surface circulation paths 14–18 July 1981 (Iyiduvar, 1986)

Figure 14. Summer surface temperature (a) and salinity (b) distribution 14–18 July, 1981 (Iyiduvar, 1986)

Figure 15. Winter surface circulation paths 14–18 April, 1984 (Iyiduvar, 1986)

Figure 16. Winter surface temperature (a) and salinity (b) distribution 17–18 April, 1984 (Iyiduvar, 1986)

Tides

Maximum observed tide height is about 40–60 cm. However, in periods of strong winds, an exceptional 150 cm increase in sea-level has been observed.

State of Pollution

Levels of pollution in Iskenderun Bay have been studied by the Institute and reviewed by Salihoglu (1986). There is a seasonal variation of pollution in the Bay. This is probably governed by seasonal changes of physical parameters and the associated changes in microorganisms. The measurements of tin, mercury and petroleum hydrocarbons display a very wide range in space and time. The observed range of this data is shown in Table 10.

Pollution levels were found to be very high in front of the industrial plants and pollutants become trapped in the center of gyres and transported towards the open sea by strong winds. Measurements carried out in front of the industrial discharge point have shown a high level of pollution. These are mostlyacidic discharges, with a mean pH value of 3.5. Mercury pollution has been observed near the local iron and steel factory with values up to 550 ppb (dry weight) in sediment. Chemical oxygen demand (COD) measurements in sediment are generally less than 1% of the quantitiy of organic carbon. Humic matter measurements show an average of 0.5–1 mg/l. Heavy use of pesticides may cause harmful effects on the biotope of the lagoons which drain water used for agricultural purposes.

Table 10. Observed ranges for some pollutants found in Islemderi, Nau waters