RESPONSE OF THE IRAQI MARSHES AND COASTAL ARABIAN GULF TO PRECIPITATION VARIABILITY AND ANTHROPOGENIC MODIFICATION IN THE TIGRIS-EUPHRATES WATERSHED

The Iraqi (Mesopotamian) Marshes, an extensive wetlands system in Iraq, has been heavily impacted by both human and climate forces over the past decades. Water flow through this system has significant effects on the ecosystem, both in the Marshes, and in the Gulf, where the Tigris-Euphrates system provides most of the freshwater input into the system. In the period leading up to the Second Gulf War in 2002, the marshlands were shrinking due to both a policy of draining and water diversion in Iraq and construction of dams upstream on the Tigris and Euphrates rivers. Following the war through 2006, this trend was reversed as the diversions were removed and active draining stopped. A combination of MODIS and GRACE images were used to determine the time dependent change in surface water area (SWA) in the marshes, marshland extent and variability in total water storage both upriver in the Tigris and Euphrates watersheds and in the marshlands. AVHRR sea surface temperature (SST) data from 1984-present were used to determine variability in coastal water surface temperatures near the river outfall at the Shat El Arab, and in Kuwait Bay. Results from GRACE and MODIS suggest that the post war dam removal and decreased pumping in 2003 provided only temporary respite for the marshlands, and that following this period of recovery, the marshes marsh extent was most influenced by total precipitation in the watershed. SST in the vicinity of the outfall was found to have a seasonal lowering of SST during high flow season (late winter) by as much as 5C relative to the central Gulf. Precipitation changes in the watershed calculated from TRMM and MERRA show a reduction of an average of 15% below the 15 yr mean in 2007–2011 This corresponds with published ensemble predictions for the 2071–2099 time period, that suggested similar marshland shrinkage should be expected in that time period, and lower discharge to the Gulf may affect the estuarine ecosystem.