Ceyhan River

The Ceyhan River is one of the longest rivers in southern Türkiye that flows into the Mediterranean Sea. With a total length of approximately 509 kilometers, the river originates at the Pınarbaşı locality in the Elbistan district of Kahramanmaraş and empties into the Mediterranean via the İskenderun Gulf. Its flow regime varies seasonally, with high discharge periods typically occurring during spring due to snowmelt and rainfall.

The Ceyhan River is regarded as one of the two primary life sources of Çukurova and holds strategic importance for both agriculture and settlement in the regions it traverses. The river flows through provinces such as Kahramanmaraş, Osmaniye, and Adana, forming an extensive delta before reaching the sea. Its main tributaries include the Söğütlü, Hurman, Göksun, Mağara Gözü, Fırnız, Tekir, Körsulu, and Aksu streams.

Ceyhan River (Anadolu Agency)

Climate and Soil Structure

The Ceyhan River basin lies within the transition zone between Mediterranean and continental climates. In the lower reaches, particularly around Adana and Osmaniye, the Mediterranean climate dominates, characterized by hot, dry summers and mild, wet winters. In contrast, the upper reaches, especially in the highland areas of Kahramanmaraş and Sivas, exhibit more continental climatic conditions, with cold and snowy winters.

These distinct climatic zones directly influence the river’s flow regime and recharge patterns; snowmelt and precipitation regimes are decisive factors in the seasonal variations of the Ceyhan River’s discharge. Environmental monitoring studies conducted in the Ceyhan Basin have revealed that the region’s soil structure is heterogeneous. The soils in the basin generally consist of alluvial soils, red Mediterranean soils (terra rossa), colluvial deposits, and rendzinas. In the middle and lower reaches of the river, particularly as the Çukurova region is approached, fertile agricultural soils formed by alluvial deposition become widespread. This condition has made the Ceyhan River basin one of Türkiye’s most important agricultural areas.

The soils in the region are rich in both agricultural productivity and plant diversity. A wide variety of crops, including wheat, cotton, and maize as the primary products, are cultivated in the areas irrigated by the river. However, in some sub-basins, soil fertility is threatened by erosion, overgrazing, and agricultural expansion.

Agricultural Activities and Irrigation

The Ceyhan River serves as the primary water source for agricultural production in the regions it flows through. Especially in the eastern part of Çukurova, in the provinces of Adana, Osmaniye, and Kahramanmaraş, the river’s waters are used to irrigate both the alluvial fertile plains along the coast and the sloping lands of the middle basin. The Ceyhan Basin stands out as one of Türkiye’s most productive agricultural regions, where crops such as wheat, maize, cotton, citrus fruits, soybeans, peanuts, sunflowers, and vegetables are intensively cultivated.

Numerous dams and regulators along the Ceyhan River form the foundation of the irrigation infrastructure. Major water structures, including Aslantaş, Menzelet, Sır, Berke, Kılavuzlu, and Kandil Dams, have been constructed primarily for irrigation and hydropower generation. Through these dams, river water is regulated and directed to agricultural lands, thereby balancing seasonal water shortages.

However, the widespread expansion of irrigation activities has brought about several environmental challenges. The intensive use of river water for agricultural irrigation has led to seasonal reductions in water volume, deterioration of water quality, and weakening of sediment transport. This situation is one of the main factors accelerating coastal erosion in the areas of the Ceyhan Delta that interface with the sea.

On the other hand, the expansion of agricultural land within the Ceyhan Delta Important Natural Area has exerted pressure on natural habitats. The opening of new farmland near abandoned sections of the riverbed has contributed to the shrinkage of wetland areas.

For sustainable agriculture in the Ceyhan Basin, irrigation management strategies have been developed. Under the Basin Protection Action Plan, initiatives such as domestic and industrial wastewater management, diffuse pollution control, and drought management have been launched. Additionally, techniques such as monitoring irrigation water quality, reducing pollution loads, and reusing treated water are being promoted to make agricultural activities in the basin more sustainable.

Morphological Changes and Delta Dynamics

One of the most significant morphological changes in the Ceyhan River occurred following the flood event of 1935. During this event, the river abandoned its existing channel and shifted southward, beginning to discharge into the sea at the southern tip of its delta. This new course triggered major changes in the delta lobe; approximately 57.3% (17.7 km²) of Akyayan Lake was converted into land.

After avulsion, a new delta lobe rapidly developed at the river’s new mouth during the 1960s and 1970s, with an average progradation rate of 53.9 meters per year toward the sea. In contrast, along the abandoned former river mouth, a coastal retreat of 1,585 meters occurred, corresponding to an average annual retreat rate of 26 meters per year.

Impact of Dams and Sediment Dynamics

The Aslantaş Dam, commissioned in 1984, is the most significant anthropogenic factor affecting the delta’s morphology. This dam has drastically reduced the sediment load delivered to the delta, halting coastal accretion and accelerating erosion. Before the dam’s construction, the river transported approximately 19,795 tons of sediment per day; after its completion, this value dropped to 4,879.7 tons per day. This reduction halted sand accumulation in the delta and triggered a reverse process: coastal erosion.

After the construction of dams, a 660-meter coastal retreat occurred along the river’s new mouth between 1992 and 2014; this situation significantly increased morphological disturbances in the southern part of the delta. Today, the delta faces serious coastal retreat threats both to the east due to avulsion and to the south due to dams.

Hydrological Characteristics

Numerous dams have been constructed along the river. One of the most prominent is the Aslantaş Dam, which became operational in 1984. This dam substantially reduced the sediment load carried by the Ceyhan River and altered the morphological structure of the delta. Before 1984, the river transported an average of 19,795 tons of suspended sediment per day; after the dams came online, this quantity decreased by approximately 75% to 4,879.7 tons per day.

Analyses of surface waters in the Ceyhan Basin have evaluated key water quality parameters such as electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), calcium (Ca), and magnesium (Mg). Studies have also revealed the presence of pollution issues such as heavy metal contamination (e.g., Cu, Fe, Zn, Ni, Pb) in certain water sources.

Water temperatures in the dams and reservoirs connected to the river system ranged from 8.1–26.7 °C, pH values from 8.0–8.6, and dissolved oxygen levels from 3.97–12.09 mg/l. According to factor analysis applied to the Ceyhan River basin, the chemical and physical properties of the water were classified into five main dimensions; the most influential variables among these were conductivity, dissolved solids, and hardness. Additionally, since 2010, under the Basin Protection Action Plan, monitoring systems for water quality have been developed, with measurements taken at 53 monitoring points. As a result of these efforts, 40 uncontaminated reference water sources have been identified in the Ceyhan Basin.

Ceyhan River (Anadolu Agency)

Ecosystem and Biodiversity

The Ceyhan River and particularly the Ceyhan Delta host one of Türkiye’s most ecologically rich wetland systems. The delta provides habitat for a wide variety of ecosystems including lagoons, reed beds, saline marshes, dunes, maquis communities, and agricultural lands. This habitat diversity offers a vital living space for numerous species, including endemic plant species, birds, mammals, fish, reptiles, and invertebrates. Floristic studies in the region have identified 17 plant taxa that meet the criteria for Important Natural Areas (INA). Notable among these are endemic species unique to Türkiye such as Astragalus subuliferus, Bupleurum zoharii, Centaurea calcitrapa ssp. cilicica, Iris xanthospuria, and Tordylium elegans. Aleppo pine (Pinus halepensis) forests, which extend across the dunes between Ömer Lake and Yumurtalık Lagoon, also form part of the region’s native vegetation.

Due to its location along major bird migration routes, the Ceyhan Delta is of great importance for both breeding and wintering bird species. Species such as the Kentish plover (Charadrius alexandrinus), collared pratincole (Glareola pratincola), little tern (Sterna albifrons), and spiny-tailed lizard (Vanellus spinosus) breed in the delta, while important wintering waterbirds include the white-headed duck (Oxyura leucocephala), northern shoveler (Anas penelope), common shelduck (Tadorna tadorna), and Caspian tern (Sterna caspia). During migration periods, the area is also used by flamingos (Phoenicopterus roseus), storks (Ciconia ciconia), and spoonbills (Platalea leucorodia).

The delta is not only vital for birds but also serves as an important habitat for various mammal and reptile species. Mammals such as the Eurasian otter (Lutra lutra) and the Anatolian ground squirrel (Spermophilus xanthophrymnus) live in the delta. Moreover, the Ceyhan Delta is a significant nesting area in the Eastern Mediterranean for two endangered sea turtle species: the loggerhead sea turtle (Caretta caretta) and the green sea turtle (Chelonia mydas). The delta is also rich in fish species, with notable examples including Alosa fallax nilotica and Aphanius fasciatus. The rare damselfly species Coenagrion syriacum also inhabits the area.

Pollution and Environmental Threats

The Ceyhan River and its basin are subject to various types of pollution and environmental threats due to intense agricultural, industrial, and urban activities. Agricultural practices, industrial effluents, and wastewater from settlements negatively impact river water quality. Hydrogeochemical analyses conducted between Eskikent and Bebeli have revealed seasonal variations in heavy metal concentrations. Additionally, it has been reported that wastewater from Osmaniye’s urban sewage system is discharged into the Ceyhan River, threatening wetland ecosystems.

Another significant threat is the uncontrolled expansion of agricultural land. New fields are being opened around the abandoned former riverbeds, leading to habitat loss and altered sediment input into the delta system. Overgrazing is another widespread threat; herds of cattle and sheep entering the area from early morning cause damage to the natural vegetation throughout the day.

Sustainability

Climate change, fluctuations in precipitation patterns, and declining groundwater levels threaten the future of the Ceyhan River. Increased evaporation during summer months leads to lower water levels, directly affecting agricultural productivity. Policies promoting sustainable water use, widespread adoption of drip irrigation systems, and protection of water basins are essential for the region’s future.