A 50,000 km² basin has no sea outlet. Water only evaporates from salt lakes. Isotope analysis shows groundwater residence times exceeding 10,000 years, meaning current irrigation unsustainably mines ice-age precipitation trapped in aquifers.
NASA, Public domain, via Wikimedia Commons
A basin with no exit
The Konya Closed Basin in central Anatolia is a vast, semi-arid plain covering approximately 50,000 square kilometers. It is an endorheic basin, a hydrological term for a closed drainage system with no outflow to the sea. The surrounding Taurus and Sultan mountains effectively trap all precipitation within the plain. With no river to carry water away, the only exit is through evaporation. This process concentrates salts and minerals, creating hypersaline lakes and salt flats.
The main feature is Lake Tuz (Tuz Gölü), Turkey's second-largest lake. During the wet spring, it can cover over 1,600 square kilometers, but its average depth is less than half a meter. In the hot, dry summer, most of the water evaporates, leaving a thick crust of salt. The lake's salinity reaches 32.4%, making it one of the saltiest in the world. This environment is too harsh for most aquatic life but is a major breeding site of greater flamingos. The basin's water budget is severely imbalanced; annual water consumption is 6.5 billion cubic meters, while the total usable supply is only 4.36 billion cubic meters.
Mining prehistoric water
The agriculture that makes the Konya Plain Turkey's "granary" depends almost entirely on groundwater. Isotope analysis, including radiocarbon dating, shows the age of this water. Near the recharge zones in the Taurus Mountains, the water is recent, but as it flows underground toward the basin's center, its age increases dramatically. Along a 150-kilometer transect, groundwater ages progress from modern to approximately 40,000 years old near Lake Tuz. This "fossil water" is a finite resource and a remnant of a cooler, wetter climate during the last glacial period, between 23,000 and 17,000 years ago.
This intensive extraction of prehistoric water is unsustainable. Annual groundwater abstraction of 2.6 billion cubic meters has caused water levels to drop by an average of one meter per year for decades. In some areas, the water table has fallen by 40 meters since 2000. This depletion has visible and dangerous consequence: land subsidence and sinkholes. As the water that supported the subterranean geological structures is removed, the ground above collapses. Some areas are subsiding by as much as 90 millimeters per year. The number of sinkholes, known locally as "obruks," has surged to over 2,600, with some measuring 50 meters deep.
💡Fun Facts
Lake Tuz provides about 70% of all salt consumed in Turkey.
The largest breeding colony of greater flamingos in the Mediterranean basin is found at Lake Tuz.
The number of sinkholes in the region has risen dramatically, approaching 3,000 in some counts.
The ancient Neolithic settlement of Çatalhöyük, one of the world's first agricultural societies, developed within this basin around 8,000 BC, relying on its unique water systems.
The geological basin is an open landscape, accessible 24/7. Specific attractions like the shores of Lake Tuz are always open.
Admission
Free
Accessibility
The Konya Plain is extremely flat and accessible by vehicle. Roads are generally well-maintained. Reaching the edge of specific sinkholes or salt flats may require walking over uneven, unpaved ground.
The Konya Closed Basin HydrologyKonya Province, Turkey