Impact of climate variability on the surface of Lake Tuz (Turkey), 1985–2016

Lake Tuz is a hypersaline lake located on the Central Anatolia plateau. The lake is one of the most important wetlands in Turkey, due to its unique ecosystem and biota, but it has been degraded due to the loss of most of its water-covered area. This study analyzes the changes at the surface of Lake Tuz over the past 32 years and discusses the relationship between this change and climatic factors. This study was made in two parts: (1) surface changes of the lake during the period 1985–2016 were evaluated based on satellite images, and (2) the relationship between surface change and climatic factors was studied using standardized precipitation index (SPI), Palmer Drought Severity Index (PDSI), and Erinç aridity index (EAI). Even though standardized spring precipitation at Lake Tuz Basin have not revealed any statistically significant long-term trend during the study period, it tended to decrease apparently during a long period from the year 2001 to 2013. This drought period was also evident in the series of 12-month PDSI during the 2002–2009 periods along with the years of 2012 and 2013. It is detected a statistically significant negative relationship between the salt-covered areas and EAI (r = − 0.63) in the long term (1985–2016). For the first period prior to the 2000s, the relationship between EAI and the salt-covered area was weaker (r = − 0.46), mostly because the lake was not significantly affected by the lack of precipitation yet due to the sufficient groundwater level. Since about 2000, groundwater withdrawals, rising temperatures, and severe and more frequent droughts strengthened the relationship between the lake’s salt-covered area and EAI (r = − 0.88). Precipitation records of Lake Tuz Basin showed a significant negative relationship with the indices of North Atlantic Oscillation (NAO), Arctic Oscillation (AO), and winter North Sea Caspian Pattern during the study period. The persistence of NAO and AO indices in a positive phase over the last 20 years has partly explained the decrease in the water-covered area observed in the lake.