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Göksu
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| Göksu River | |
|---|---|
Göksu River and Silifke Castle | |
![]() | |
| Location | |
| Country | Turkey |
| Physical characteristics | |
| Source | |
| • location | Taurus Mountains |
| Mouth | Göksu Delta |
• location | Mediterranean Sea near Silifke |
• coordinates | 36°17′48″N 34°2′48″E / 36.29667°N 34.04667°E |
| Length | 260 km (160 mi) |
The Göksu River (Turkish: Göksu Nehri), known in antiquity as the Calycadnus and in the Middle Ages as the Saleph, is a river on the Taşeli Plateau in southern Turkey. Its two sources arise in the Taurus Mountains—the northern in the Geyik Mountains and the southern in the Haydar Mountains—and meet south of Mut. The combined stream then flows south to the Göksu Delta in the Mediterranean Sea near Silifke.
Names
[edit]Göksu is Turkish for "Sky Water". It is also known as the Geuk Su.[citation needed][clarification needed] It was known to the ancient Greeks as the Kalýkadnos (Καλύκαδνος), latinized as the Calycadnus. It was known in the Middle Ages as the Saleph.[why?]
Course
[edit]The river is 260 km long and empties into the Mediterranean Sea 16 km southeast of Silifke (in Mersin province). The Göksu Delta, including Akgöl Lake and Paradeniz Lagoon, is one of the most important breeding areas in the Near East; over 300 bird species have been observed. Among others, flamingos, herons, bee-eaters, kingfishers, gulls, nightingales and warblers breed here. The endangered loggerhead sea turtle (Caretta caretta) lays eggs here.
Due to demand for summer vacation apartments by the locals, and since necessary precautions are not taken and public attention is minimal in this part of Turkey, the ecosystem around Akgöl Lake and Paradeniz Lagoon is in heavy danger.
History
[edit]Iron Age
[edit]The Ionian Greek colony of Holmi was founded near the mouth of the Calycadnus but suffered from piracy and raiders.
Classical Age
[edit]Seleucia, the modern Silifke, was founded at a more defensible position a little further up the river by Seleucus I Nicator and was an important regional center for centuries, particularly noted as a center of early Christianity. The Romans bridged the river at Seleucia in 77 AD.
Middle Ages
[edit]Third Crusade
[edit]
In 1190, while on the Third Crusade, Emperor Frederick Barbarossa drowned in the river, then known as the Saleph and located within the Armenian Kingdom of Cilicia. The crusaders had reached Asia Minor in March, where the emperor continued his campaign to the Holy Land. Having plundered the city of Konya and defeated the forces of the Sultanate of Rum at the Battle of Iconium, his forces arrived on the banks of the river on June 10. Several contradictory statements reflect the circumstances of his sudden death, which have not been conclusively established. According to some sources, the emperor was lost in the current when he tried to cross the water near Silifke; other chronicles report he wished to cool down from the heat of the day and suffered a heart attack while taking a bath. The mortal remains were preserved according to the Mos Teutonicus process and transferred to Tarsus, Antioch and Tyre by his followers. Once without a leader, his crusader army dispersed; the remnants later joined the Siege of Acre. A monument in Barbarossa's honor was erected on the road from Silifke to Mut.
See also
[edit]References
[edit]Göksu
View on GrokipediaNames and Etymology
Historical Names
The Göksu River was known in antiquity as the Calycadnus (Ancient Greek: Καλύκαδνος), a name appearing in classical geographical descriptions of Cilicia Trachea in southern Anatolia.[8][9][10] This designation reflected its role as a key waterway traversing the Taurus Mountains and emptying into the Mediterranean near Seleucia (modern Silifke).[8] In medieval Latin sources, particularly Crusader chronicles, the river was called the Saleph, a name tied to its identification during the Third Crusade.[11][4] Holy Roman Emperor Frederick I Barbarossa drowned while attempting to cross it on June 10, 1190, near Silifke, an event that contributed to the fragmentation of his army en route to the Holy Land.[11][4] The Saleph nomenclature persisted in European accounts into the early modern period before yielding to the Turkic Göksu, meaning "sky water" or "blue water."[12]Modern Designations
The Göksu River is officially designated in Turkish as Göksu Nehri, a name derived from the Turkic elements gök ("sky" or "heaven") and su ("water"), evoking "sky water" or "celestial water" in reference to its origin in the high Taurus Mountains and the clarity of its flow.[13][14] In English-language geographical and scientific contexts, it is consistently rendered as the Göksu River, with occasional older romanizations such as Geuk Su appearing in historical transliterations but not in current usage.[14] The river's delta region carries multiple legal designations under Turkish environmental law, including Natural Site status, Special Environment Protection Area (established in 1990 over 23,600 hectares), and Wildlife Protection Area for associated lagoons such as Akgöl and Paradeniz.[15][16] Internationally, the Göksu Delta was designated as a Wetland of International Importance (Ramsar Site no. 657) on 13 July 1994, recognizing its role in supporting migratory bird populations and Mediterranean biodiversity.[15] These protections encompass the lower river course but do not extend uniformly to the upstream basin, where hydroelectric infrastructure has been developed since the 1990s.[17]Physical Geography
Course and Path
The Göksu River originates from two primary headwater streams in the Central Taurus Mountains, with one branch rising in the Geyik Mountains and the other in the Haydar Mountains; these tributaries converge south of the town of Mut in Mersin Province to form the main river.[14] From the confluence, the river flows southward for a total length of 260 kilometers across the Taşeli Plateau, traversing the Rough Cilicia region through rugged terrain that includes fertile basins near the junctions with tributaries like the Ermenek Çayı, short canyons between villages such as Kışlaköy and Karğıcak, and a steep gorge ascending toward the Anatolian plateau. It passes key settlements including Mut (ancient Claudiopolis) and Değirmendere before reaching the coastal plain.[14][9] The river's path culminates in the Göksu Delta, a wetland area spanning lagoons such as Akgöl and Paradeniz, located between Taşucu and Silifke, where it empties into the Mediterranean Sea approximately 16 kilometers southeast of Silifke. This course supports diverse hydrological and ecological features, with a wide riverbed in sections suitable for activities like rafting.[14][9]Basin Characteristics and Geology
The Göksu River basin covers an area of approximately 10,000 km² in southern Turkey, encompassing parts of the Taurus Mountains and extending to the Mediterranean coast near Silifke in Mersin Province.[18] The basin's drainage network exhibits a dendritic pattern influenced by the underlying lithology and tectonic structures, with the river originating at elevations exceeding 2,000 m in the mountainous headwaters.[19] Morphometric analyses reveal a relatively elongated basin shape, characterized by high relief ratios and a V-shaped transverse valley profile in upstream sections, indicative of active fluvial incision and limited lateral erosion.[19] Geologically, the basin spans rock units from Ordovician basement formations to Miocene sediments, overlain by Quaternary alluvial and colluvial deposits.[20] The substrate includes heterogeneous mixtures of metamorphic rocks, limestones, and basin-fill sediments, with horizontal bedrock layers intermittently disrupted by NE-SW trending faults such as the Göksu fault, contributing to localized tectonic uplift.[21] [22] Predominant soil types comprise alluvium in the lower reaches, colluvium on slopes, brown earths, and red Mediterranean soils, reflecting the interplay of fluvial deposition and pedogenic processes under a semi-arid climate.[23] Quaternary fluvial dynamics have produced a prominent staircase of 16 river terraces (T16 to T1), elevated 10 to 365 m above the modern thalweg, recording episodes of aggradation and incision driven by tectonic base-level changes and climatic fluctuations, including Marine Isotope Stage transitions.[24] The modern river features gravel-bed channels with low sinuosity, point bars, and chute cutoffs, while geomorphic hazards like the Mahras Dağ complex landslide in the upper valley highlight slope instability in tectonically active zones with paleolake remnants up to 350 m elevation.[25] [21] Local tufa precipitation occurs in karstic reaches, such as the 500 m-long natural bridge at Yerköprü, where geomorphological controls favor calcium carbonate deposition from groundwater seepage.[26]Hydrology
Flow Dynamics and Discharge
The Göksu River exhibits a pluvial flow regime characteristic of Mediterranean rivers, with discharge heavily influenced by seasonal precipitation and snowmelt from the Toros Mountains. Average annual discharge at the river mouth is approximately 130 m³/s, reflecting a total annual volume of about 3.671 billion cubic meters over its 10,400 km² basin.[18][27] Flows peak during winter and early spring due to intense rainfall and melting snow, often exceeding 500 m³/s during wet periods, while summer baseflows drop below 20 m³/s amid high evaporation and reduced precipitation.[28] Hydrological data from observation stations, such as those monitoring 1984–2022 monthly averages, reveal significant interannual variability, with extreme highs in years like 2014 driven by anomalous precipitation events and lows during droughts.[29] Flood dynamics are pronounced in the upper and middle reaches, where steep gradients and narrow valleys amplify peak flows; historical flood frequency analyses indicate return periods for discharges over 1,000 m³/s ranging from 10–50 years, modulated by upstream geology including karstic aquifers that contribute baseflow stability.[30] Downstream, the river's meandering course and deltaic sedimentation reduce velocity, with flow velocities averaging 0.5–1.5 m/s in the lower basin, facilitating sediment transport rates estimated at 1–2 million tons annually.[31] Anthropogenic factors, including upstream dams like Feke I, have altered natural flow duration curves since their construction, shifting from highly variable pre-dam regimes (with 10% exceedance flows up to 300 m³/s) to more regulated post-dam patterns that mitigate floods but reduce low-flow durations.[32] Despite regulation, the river retains sensitivity to climate variability, with recent studies forecasting potential 10–20% discharge reductions under warming scenarios due to decreased snowfall and increased evapotranspiration.[29]Infrastructure and Modifications
The Göksu River has undergone modifications primarily through dam construction for hydroelectric power, flow regulation, and inter-basin water transfer, alongside irrigation networks and flood mitigation efforts. Key structures include the Ermenek Dam and associated hydroelectric power plant on the upper river in Karaman Province, completed in 2012 with an installed capacity exceeding 400 MW, designed to harness the river's flow for energy production while altering natural discharge patterns downstream.[33] Additional dams, such as those in the Mut and Silifke districts including Kayraktepe and Mut Dams, support local irrigation and flood management by storing water and controlling seasonal peaks.[34] Water diversion infrastructure significantly impacts the basin's hydrology, with the Bağbaşı Dam on the tributary Eğiste Deresi storing up to 205 million cubic meters for transfer via the 17 km-long Blue Tunnel (Mavi Tünel), operational since 2012, to irrigate arid lands in the Konya Closed Basin covering approximately 296,455 decares.[35] [36] This system reduces available downstream flow for the Göksu, prioritizing agricultural expansion in endorheic regions over local riparian uses. Complementary irrigation facilities, like the Göksu Basin Hillside Lands project, employ pressurized pipe networks to service 2,939.5 hectares of sloped terrain, enhancing agricultural productivity but increasing evaporation losses compared to traditional methods.[37] Flood control measures focus on the lower river, particularly a 5.375 km section in Silifke district, where feasibility studies have informed bed stabilization, embankment reinforcements, and channel modifications to mitigate inundation risks from heavy rainfall and snowmelt, though full implementation details remain tied to ongoing State Hydraulic Works (DSİ) projects.[38] These interventions collectively reduce peak flows and sediment transport, altering the river's natural morphology and downstream delta dynamics, with hydrological models like HEC-HMS and HEC-RAS used to assess impacts and guide further adaptations.[39]Ecology and Biodiversity
Delta Formation and Wetlands
The Göksu Delta develops at the confluence of the Göksu River with the Mediterranean Sea in Mersin Province, southern Turkey, primarily through the deposition of alluvial sediments eroded from the Taurus Mountains and transported downstream. As the river's velocity decreases upon entering the low-gradient coastal zone, suspended sediments settle, building up lobes of silt, sand, and clay over millennia, with fluvial dynamics driving ongoing erosion and accretion processes.[40][41][42] This sediment accumulation has formed a dynamic, low-relief landscape spanning approximately 15,000 hectares, characterized by minimal tidal influence due to the microtidal Mediterranean regime, which limits marine incursion and favors river-dominated progradation.[43][44] The resulting wetlands comprise a mosaic of habitats, including freshwater lakes (such as Paradeniz Lake), brackish lagoons, extensive reed marshes, halophytic salt marshes, and stabilizing sand dunes along the shoreline.[45][46] These features are sustained by seasonal river inflows, groundwater seepage, and episodic flooding, creating salinity gradients from freshwater-dominated inland areas to hypersaline coastal fringes.[40][44] Designated a Ramsar Wetland of International Importance in 1994 and a Special Environmental Protection Area, the delta's wetlands exhibit zonation patterns influenced by elevation, hydrology, and soil salinity, with vegetation transitions from emergent macrophytes in marshes to succulent halophytes in saline zones.[47][43][46] Human modifications, including limited damming upstream, have subtly altered sediment budgets, potentially reducing deposition rates, though the core wetland structure remains largely intact.[41][48]Flora, Fauna, and Ecosystems
The Göksu Delta, encompassing the river's estuary, features a mosaic of wetland ecosystems including freshwater marshes, salt marshes, sand dunes, and coastal lagoons, which collectively support high levels of biodiversity characteristic of Mediterranean coastal wetlands. These habitats are influenced by seasonal flooding and salinity gradients, fostering dynamic ecological interactions between terrestrial, aquatic, and marine components. The delta's productivity stems from nutrient inputs from the Göksu River, making it one of Turkey's most biologically rich areas, designated as a Ramsar wetland site in 1994 for its role in supporting migratory and resident species.[16][43] Vegetation in the Göksu Delta is stratified into three primary habitat groups: aquatic (dominated by submerged and emergent macrophytes in rivers and lagoons), sand dune (with psammophytic species adapted to shifting sands), and halophytic (salt-tolerant communities in marshes). Phytosociological analyses identify associations such as Phragmito-Magnocaricetea in freshwater zones and Salicornietea in saline areas, with a total of 442 vascular plant species recorded, including eight endemics such as Silene villosa subsp. bivonae and Onosma caerulescens. These plant communities provide critical structural support for habitat complexity, though they face pressures from erosion and invasion by non-native species.[46][16] Faunal diversity is pronounced, particularly among avifauna, with over 330 bird species documented, including breeding populations of vulnerable species like the purple gallinule (Porphyrio porphyrio) and marbled teal (Marmaronetta angustirostris), alongside wintering flocks of flamingos (Phoenicopterus roseus) and herons. The ichthyofauna comprises at least 59 fish species in the delta vicinity, spanning families such as Cyprinidae and Salmonidae, with notable natives including the endemic Chondrostoma toros and migratory Anguilla anguilla; ichthyoplankton peaks in summer, indicating key spawning grounds. Invertebrates and reptiles, including nesting loggerhead sea turtles (Caretta caretta) on beaches, further enhance trophic webs, though mammalian records are sparser and tied to riparian zones.[49][50][51]Threats and Conservation Measures
The Göksu Delta and its associated wetlands encounter multiple anthropogenic threats that compromise their ecological integrity. Dams on the Göksu River, including those constructed upstream, have curtailed sediment delivery to the delta, leading to erosion, habitat degradation, and reduced wetland accretion rates critical for maintaining biodiversity hotspots.[46] Agricultural intensification introduces non-point source pollution through drainage channels carrying pesticides, fertilizers, and nutrients into lagoons and rivers, fostering eutrophication and algal blooms that disrupt aquatic ecosystems.[52] [15] Inadequate domestic waste management in delta-adjacent towns, where systematic collection is absent, results in untreated effluents contaminating surface and groundwater, exacerbating pollution loads.[53] Historical river channel modifications for flood control have altered natural flow regimes, diminishing floodplain connectivity and wetland hydrology. Illegal hunting, evidenced by persistent litter from spent cartridges, poses risks to waterfowl populations despite regulatory prohibitions.[54] Conservation initiatives prioritize habitat preservation and threat mitigation through legal designations and scientific oversight. The delta was designated a Ramsar Wetland of International Importance on September 24, 1994, encompassing 14,952 hectares to protect its role in supporting migratory birds, endemic plants, and marine turtle nesting sites.[15] In 1990, Turkey established 23,600 hectares as a Special Environment Protection Area under national law, imposing restrictions on development to conserve ecological, historical, and cultural features.[43] Complementary efforts include ongoing monitoring by organizations such as the Turkish Society for the Protection of Nature, which maps habitat types, tracks endangered species like the ferruginous duck and summer duck, and evaluates pollution impacts to inform adaptive management.[49] These programs, aligned with EU environmental directives and national wetland policies, emphasize research-driven interventions, though enforcement challenges persist due to local agricultural pressures.[55] Remote sensing studies further quantify land cover changes, revealing a 24.52% decline in water surface areas over recent decades, guiding restoration priorities.[52]History
Ancient and Iron Age Settlements
The Göksu River valley, known in antiquity as the Calycadnus, served as a vital corridor through the Taurus Mountains, facilitating connections between the central Anatolian plateau, such as the Konya Plain, and the Cilician coastal plains near Adana, from prehistoric times onward.[8] Archaeological surveys have identified multiple höyük (mounded settlements) in the Mut basin and lower valley, including Attepe, Kilise Tepe, Görmüttepe, and Çingentepe, with occupations dating back to the Chalcolithic period and continuing into the Early Bronze Age (c. 3100–2100 BC).[9] These sites, often paired twin mounds in fertile basins, yielded Chalcolithic ceramics and obsidian artifacts indicative of long-distance trade networks, suggesting the valley's role in early resource exchange and settlement hierarchies where larger mounds like Kilise Tepe and Attepe likely dominated smaller satellites.[9] The abundance of water from the Göksu supported agricultural productivity, making the area attractive for sustained habitation despite the rugged terrain.[56] Kilise Tepe, a prominent mound located just west of the Göksu approximately 20 km from Mut, exemplifies continuous ancient occupation, with excavations revealing stratified deposits from the Early Bronze Age through the Late Bronze Age (c. 1600–1200 BC).[57] Rescue excavations from 1994–1998 and subsequent work in 2007–2012 confirmed Late Bronze Age structures destroyed by fire, followed by Iron Age layers lacking substantial architecture in some soundings but featuring open spaces and ceramic evidence of transition.[58] This site highlights the valley's strategic position linking Anatolia's interior to the Mediterranean coast, with pottery sequences reflecting cultural influences from both highland and lowland traditions.[57] During the Iron Age (c. 1200–600 BC), settlements in the Göksu valley persisted amid regional upheavals, including the Late Bronze Age collapse and migrations such as those of the Sea Peoples in Cilicia.[59] Sites like Dinek Höyük were established in the Middle or Late Iron Age, inhabited until Byzantine times, while broader surveys documented Iron Age pottery at upper valley locations.[60] A Neo-Hittite rock relief at Keben, dating to the 11th–8th centuries BC, marks key north-south routes and originally featured painted elements, underscoring the persistence of Luwian-influenced cultural practices post-Hittite Empire.[9] Salvage surveys prior to hydroelectric developments have emphasized the valley's dense archaeological record, with höyüks showing near-continuous use from Bronze to Iron Age, though many face threats from inundation.[56]Classical Antiquity
The Göksu River, designated in ancient sources as the Calycadnus, facilitated trade and military movement in Rough Cilicia during the Hellenistic and Roman periods due to its passage through the Taurus Mountains to the Mediterranean coast.[61][62]
Seleucia ad Calycadnum, established by Seleucus I Nicator between 296 and 280 BC at the river's estuary, emerged as the principal urban center in the vicinity, supplanting or expanding prior settlements and leveraging the waterway for economic and strategic advantages.[63][64]
This city incorporated Hellenistic urban planning and Greek architectural elements, functioning as a cultural and commercial nexus amid the rugged terrain.[65]
Roman administration enhanced its infrastructure, notably with a limestone bridge spanning 120 meters across the Calycadnus, erected in 77-78 CE by provincial governor L. Octavius Memor under Emperor Vespasian to accommodate local traffic and regional connectivity.[66]
Seleucia's fortified acropolis overlooked the valley, underscoring its defensive role, while the settlement's layout extended along the riverbanks, integrating the Calycadnus into daily commerce and defense until late antiquity.[64][65]
