Transboundary River Basins in Turkey
Transboundary water courses provide roughly 70 km3 /year or 40% of the gross surface water potential originating in Turkey. The Euphrates-Tigris Basin represents about four fifths of this figure; the rest is contributed by the basins Orontes, Kura-Araks, Chorokhi, Maritza, and a few other quite small basins. Turkey is the upstream riparian in the Euphrates-Tigris, Kura-Araks, Chorokhi, and the small basins, and a downstream riparian in the Orontes and Maritza basins. The total water potential of the Euphrates-Tigris Basin exceeds 90 km3 /y, where Turkey provides, in rough figures, 60%, Iraq 25%, Iran 10% (excluding Kharkeh), and Syria 5% of it. In Turkey, the average water potential of Euphrates is around 32 km3 / y, and that in Tigris around 24 km3 /y, including tributaries flowing directly to downstream countries. Ultimately, as a long-term average, half of the EuphratesTigris water potential originating from Turkey, about 40% in Euphrates and 65% in Tigris, will continue to flow towards the downstream countries. However, the amount of water in any allocation agreement should be set according to different levels of probabilities of discharges because of the significant stochastic variation of discharges, even after regulation by the huge reservoirs in Turkey. The water potential of the transboundary Euphrates-Tigris Basin is quoted with large differences according to various sources; hence, the determination of the accurate water potential is an essential prerequisite for any allocation among riparian states and eventual diversions to other middle-eastern countries. The water potential of the Euphrates Subbasin appears to be insufficient in Iraq so that the excess water of the Tigris Subbasin should be transferred to Euphrates to satisfy the irrigation needs along the Euphrates banks in Iraq.
Keywords Turkey · Euphrates · Tigris · Orontes · Kura-Araks · Chorokhi · Maritza · Transboundary river basin · Water power · Irrigation
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