Climate, humans caused decline of once 2nd largest salt lake

The dramatic decline of Iran's Lake Urmia - once the second-largest hyper-saline lake in the world - has both direct human and climatic causes, according to new research.
"Saving Lake Urmia will require both national action to improve water management, and international cooperation to address the issue of climate change," said Somayeh Shadkam, researcher at International Institute for Applied Systems Analysis (IIASA) in the US and Wageningen University in the Netherlands.
The study was the first to compare the relative impact of climate and water management on the water flowing into the lake.
Lake Urmia was once the world's second-largest hyper-saline lake, but has declined over 80 per cent in recent decades.

Previous work by Shadkam and colleagues had shown that climate change threatens the lake's existence, using future scenarios of climate change to project water inflow into the lake.
The new study aims to better understand the causes of the lake's decline, teasing out the relative contribution of different factors such as human water usage as well as climate-related variables, using 50 years of data from 1960 to 2010.

The annual flow of water into Lake Urmia dropped by 48 per cent over the study period.
Using a model of water flow into the lake, researchers found that 60 per cent of this decline was caused by climate changes, such as change in precipitation and temperature, and that the remaining 40 per cent of the decline could be attributed to water resources development, such as diverting water for irrigation that would otherwise flow into the lake.

Most previous studies have indicated the dominate role of water usage in changes in the lake surface area.
The study indicates that climate change and variability has contributed to the lake desiccation. That means that reduced water use without taking change in the climate into account might be insufficient in saving the lake.
"Water resources and climate change are inextricably interlinked. This is just one area where an integrated systems viewpoint is vital for providing sound advice to policymakers trying to solve such pressing issues," said Pavel Kabat, Director General at IIASA.
The study was published in the Journal of Great Lakes Research.