Assessing the spatial and temporal variations of terrestrial water storage of Iraq using GRACE satellite data and reliability–resiliency–vulnerability indicators

The spatial and temporal changes of water resources of Iraq were evaluated using the Gravity Recovery and Climate Experiment (GRACE) data for the period 2002–2019. The rate of change and significance of the change in terrestrial water storage (TWS) derived from different GRACE solutions were estimated using Sen’s slope estimator and Mann–Kendall test. The sustainability of water resources was evaluated using reliability–resiliency–vulnerability indicators. Results indicated a significant decrease in water availability. The reliability (range 0.22–0.30) and resiliency (range 0.01–0.23) of water resources were low. The estimated vulnerability (range of 0–1) was highest in the north and lowest in the south and southwest. The calculated sustainability of water resources was generally low (range 0–0.36) and was higher in southern and western regions relative to northern and central areas. Anthropogenic activities and climate change (increasing temperature) play major roles in changes in water availability in Iraq.