Impact of Water Resources Utilization on the Hydrology of Mesopotamian Marshlands

Abstract

The Mesopotamian Marshlands used to be the largest wetland ecosystem in the Middle East and western Eurasia. These marshlands once covered more than 15,000–20,000 sq km with permanent lakes and marshes, seasonal marshes, and temporary marshes. Although the recent restoration efforts returned the marshes back to approximately 39% of their original spatial extent, the artificial drainage works have significantly reduced the marshes during the late 1980s and 1990s. The water resources development/utilization in the upstream regions of the Tigris-Euphrates (TE) River Basin has been considered as one of the causes for the damage of the marshland ecosystem. To assess the hydrologic conditions in the Mesopotamian Marshes under various water utilization scenarios, a marshland hydrologic model for the Hawr Al Hammar Marshes near the downstream end of the TE River Network has been developed in conjunction with the regional hydro-climate model of Tigris-Euphrates (RegHCMTE) Watershed and the water resources system model of the Euphrates-Tigris River Basin. This marshland hydrologic model accounts for rainfall, evapotranspiration, surface water inflows and outflows, and soil water inflows and outflows. In this paper, the marshland hydrologic model for the Hawr Al Hammar Marshes is described, and the reconstruction of historical marshland hydrologic data over Hawr Al Hammar Marshes by using the coupled TE modeling system is presented. By using the developed Mesopotamia Marsh model, the impact of various water resources utilization alternatives in the TE Basin on the hydrology of the Hawr Al Hammar marshes is quantified. The simulation results reveal that by treating the TE Basin as one hydrologic unit, where water is transferred from the Tigris to the Euphrates River to meet the irrigation water demands in the basin for various release scenarios from the Turkish sector, it is possible to sustain the Al Hammar Marshes at their pre-dam-construction (pre-1970) conditions in the TE Basin under severe hydro-climate conditions of the historical critical dry period.