From 2007 to 2009, northern Iraq suffered a severe drought and GRACE satellite observations indicate a water loss of about 146mm equivalent water height (EWH) in the same period. To identify the main causes of this water loss, we developed a model based on geology, remote sensing and stream flow data. Our findings indicate that anthropogenic groundwater extraction has a minor influence in this region, while a decline in lake mass and natural depletion of groundwater play a key role.