On 14th April 2017, we implemented a salinity monitoring in the Anzali Wetland to investigate intrusion of the Caspian seawater into the wetland. Electrical conductivity (EC) was measured 50 cm from the surface in different parts of the wetland as shown in the figure below. On this day, EC of the Caspian Sea outside of the Anzali Port was 20.53 mS/cm. EC in the wetland varied significantly depending on location. In Sorkhankol, which is the lowest part of the wetland, EC was as high as 9.84 mS/cm, or about 50% of the Caspian seawater. Even in the lagoon, EC was as high as 3.85 mS/cm, or 20% of the Caspian Sea. EC was lower in major channels as they are the main routes of river waters to reach the Caspian Sea.
The results clearly indicated a significant exchange of the Caspian seawater with the water in the wetland. The water level of the Caspian Sea is known to exhibit seasonal fluctuation, and it is generally high in summer. Hence, we expect the intrusion of the seawater to be most pronounced around this time of the year. The water exchange has major impact on both water quality and water level of the wetland, and it is one of the most important factors shaping the complex ecosystem of the Anzali Wetland. Unfortunately, however, the mechanism of water exchange is not well understood mainly because water level and water quality have not been monitored regularly in the past.