Euphrates & Tigris Basins

The Euphrates and Tigris basins have the highest water potential out of the 25 basins in Turkey. The former has about 32 billion m³ and the latter about 23 billion m³ of annual water potential. These two basins are very important for Turkey for utilizing water resources in the fields of energy production and irrigated agriculture. The Southeastern Anatolia Project (GAP), one of the largest infrastructure projects in Turkey, depends on the water resources of these two basins. Because the Euphrates and Tigris rivers are trans-boundary waters, they have international implications. Possessing the headwaters of these rivers, Turkey has the responsibility to release enough water across its borders to help sustain life in downstream countries like Syria and Iraq.

Climate change projections suggest reductions in precipitation and increases in temperature. The latter may enhance the atmospheric demand for water vapor. Hence, it will likely increase the evapotranspiration-the sum of evaporation and plant transpiration from earth’s surface to the atmosphere-in the region. Moreover, the enlargement of the irrigated agricultural fields in the vast plains of the upper Mesopotamia, as a result of GAP irrigation projects, will increase the loss of water through evapotranspiration. These changes will certainly result in declines in water potentials.

As can be seen from the map, the water potentials are projected to decrease by about 9-10% by the mid-century and 25-30% by the end of the century. Such reductions have the potential to adversely affect energy production, agriculture, and water release for downstream countries.

Solid lines are for 1961 – 1990 period and dashed lines are for 2071 – 2099 period