“The 150-centimeter drop in water level (over the last three decades) is also due to evaporation, low precipitation and steep decline in water flow into the lake from rivers that discharge into the earth's largest inland body of water,” Masoumeh Banihashemi was quoted as saying by IRNA.
Water level has been of the descending order over the past 30 years and several programs to slow or control the crisis have been futile, she warned.
Close to 25% of the sea’s drainage basin is in Iran. Due to inflow of fresh water in the north, sea water is fresh in the northern parts getting more brackish toward the south. It is most saline on the Iranian shore.
The sea registered a 13-centimeter drop in 2019 alone compared to the previous year, she said. Last year the Caspian water level plummeted below -27.18 meters (relative to the Baltic Sea). The Baltic Sea datum is used as a reference point to measure fluctuations in the Caspian water level.
According to Banihashemi, one of the main malefactor behind the rapidly declining water level is evaporation over the sea (due to climate change and global warming), causing more harm than the limited river discharge and precipitation.
The sea supports many unique and ancient species from the time when it was part of the Tethys Ocean during the Mesozoic era, approximately 300 million years ago
“Evaporation has contributed to about half of the decline and the combined effect of low rainfall and river discharge changes have contributed to the other half.”
Studies by WRC show that if temperature in the Caspian Sea region (up 1 degree Celsius in 30 years) continues to rise loss from evaporation will make a bad situation worse.
“Unless river discharge rises accordingly or precipitation in the Caspian drainage basin increases, the imbalance is likely to continue (as the planet warms)."
In addition to irreparable ecological harm, the reducing water level has led to the shrinkage of territorial waters. In some regions around the Caspian coastlines have receded between 60 to 200 meters as territorial waters deplete.
According to the official, an estimated 300 billion cubic meters of water flows into the sea annually from its tributaries, the largest being the Volga River that runs through Russia and discharges around 240 bcm into the lake.
The inflow dwindled 22% last year not only due to low precipitation but also because of mega structures (floodgates and levees) being built by the Caspian Sea littoral states (Iran, Russia, Azerbaijan, Kazakhstan and Turkmenistan) on the river.
Round the globe, climate change is warming many lakes faster than it’s warming the oceans and the air, the National Geographic has reported. This heat accelerates evaporation, conspiring with human mismanagement to intensify water shortages, pollution, and loss of habitat for birds and fish. But while the fingerprints of climate change are everywhere, they don’t look the same in every lake, it said.
Rising Risks
In related news Mohammad Darvish, an environmentalist and a researcher at the Research Institute for Forests and Rangelands based in Tehran, said a more serious threat to the lake is water quality that has deteriorated over the years.
“Water pollution level in the lake is 40 times over and above international norms,” Darvish added. Shipping in the sea is another growing problem contributing to the high pollution level.
Moreover, the release of over one billion cubic meters of industrial, chemical and household wastewater into the sea per annum has polluted the water and reduced oxygen levels jeopardizing 400 plus aquatic species, including the world famous Caspian sturgeon.
Oil exploration and transportation are other sources of pollution. According to published surveys, the sea contains close to 33 billion barrels of oil. Proven natural gas reserves region are estimated at 5 trillion cubic meters.
Referring to water mismanagement and disorganized exploitation of groundwater resources, he said approximately 65% of Iran’s need for potable water comes from underground sources namely wells, qanat water systems and mineral springs that have been depleting at an alarming rate.