Examining Temporal and Spatial Variations of Soil Moisture in Iraq

This study aimed to evaluate the temporal and spatial variations in surface soil moisture in Iraq, taking into account the influence of both natural fluctuations and human activities on environmental changes. Volumetric soil moisture data with a resolution of 0.25 degrees and daily intervals covering a thirty-year period (1991-2020) were obtained from the Copernicus climate database. Trend analysis was conducted to examine temporal and spatial trends in soil moisture levels. The results indicated a decrease in volumetric soil moisture during warm months and an increase during cold months, with the latter period exhibiting soil moisture values more than twice as high as the former. Furthermore, a declining trend in volumetric soil moisture during the cold months in Iraq was observed based on the evaluation of monthly time series. The average annual volumetric soil moisture in the country was estimated to be 0.164 m3/m3. The lowest soil moisture value was found in southern Iraq near the border with Kuwait (0.093 m3/m3), while the highest value was recorded in the northeastern mountainous region of Iraq (0.240 m3/m3). Notably, there was a gradual decrease in soil moisture from north to south in Iraq. The analysis of maps revealed that the most substantial decreasing trends occurred in January, February, and March, progressively diminishing as the warm season approached. These decreasing trends were predominantly observed along the rivers of Tigris and Euphrates, as well as around the Razazah Lake and the Tharthar Lake extending from northwest to southeast. The provinces of Diyala, Maysan, and Wasit, particularly Wasit, consistently exhibited decreasing trends in soil moisture in most months, indicating their vulnerability to soil moisture reduction.