Jezira Tertiary Limestone Aquifer System

The Jezira Tertiary Limestone Aquifer System (JTLAS) comprises two Paleogene Formations: an Eocene (main aquifer) and a Lower Oligocene Formation. It extends from the Jezira Plain on Syria’s northern border (Upper Jezira area) into the south-eastern Anatolian Highlands in Turkey.

Large volumes of groundwater flow from recharge areas in the highlands to groundwater discharge areas along the Syrian border, where many springs, most importantly the Ras al Ain and Ain al Arous Springs, discharge from the aquifer system. Until approximately 2000, these springs discharged a total volume of more than 1,200 MCM and formed the principal source of surface flow in the Balikh and Khabour Rivers, which are the main tributaries of the Euphrates River in Syria.

In recent years, there has been a significant shift away from rain-fed irrigation to groundwater irrigation in the area and today almost 6,000 wells (around 2,000 in Turkey and 4,000 in Syria) abstract about 3,000 MCM/yr of water from the aquifer system. These high abstraction levels have significantly affected the groundwater regime and led to a dramatic decrease in springs discharge. Thus the springs at Ras al Ain, which used to supply 87% of the total discharge from the aquifer have practically dried up.