A basin’s response to rainfall is not determined by the amount of rain alone; the surface on which the rain falls decides how much infiltrates and how much runs off. For this reason, land use and land cover (LU/LC) maps are a fundamental input to hydrological modeling, because they reveal which parts of a basin are bare, built-up, vegetated, or covered by water, how these parts change over time, and what effect this has on surface runoff. In the study under discussion, LU/LC maps were produced for two basins in the Middle Euphrates region: the Hilla Basin, with an area of about 1,368 km², and the Diwaniyah Basin, with an area of about 1,432 km². The study relied on Landsat 5 and Landsat 8 satellite imagery after geometric and atmospheric correction, and the images were then classified using the supervised Maximum Likelihood method in ArcGIS into five classes: barren land, built-up areas, water, rangeland, and crops. The maps show that barren land dominates both basins, accounting in 2018 for about 73% of the Hilla Basin and about 83% of the Diwaniyah Basin. Between 2002 and 2018, built-up area in Hilla nearly doubled, from 41 to 80 km², while in Diwaniyah it more than doubled (by a factor of about 2.5), from 38 to 96 km². In contrast, rangeland declined by about 16% in Hilla and about 55% in Diwaniyah, and crop area in Hilla fell by about 73%, from 95 to 25 km². Water bodies in Hilla increased from 15 to 56 km², which may be related to differing hydrological conditions between the two comparison years. To project future conditions, the MOLUSCE plugin in QGIS was used, which combines multilayer perceptron artificial neural networks (ANN-MLP) with cellular automata (CA). The process began by computing the transition matrix between classes for the period 2014–2018, followed by an analysis of driving factors using the Pearson correlation coefficient, and then a simulation of the year 2022, which was validated by comparing it with the actual map. Once validation succeeded, later years were predicted. The validation kappa value was about 0.93 for Diwaniyah and about 0.87 for Hilla, both high values indicating good agreement between the simulation and reality. The results anticipate relative stability in land cover over the coming decades: barren land remains at about 83% in Diwaniyah and between 72% and 73% in Hilla until mid-century. The modeling projects a slight increase in rangeland: in Hilla it rises from 17.4% to 19.3% by 2042, and in Diwaniyah from 10.2% to 11.1% by 2050, with a decline in crops and water bodies in Hilla. As for the effect on runoff, the study models it using the Curve Number (CN) value in the SCS-CN method, which combines soil type and land use into a single number; the higher the number, the greater the runoff. CN values were high in all sub-basins, between about 88 and 91, which means the soil is nearly impervious and generates substantial runoff. These values rose slightly from 2002 to 2018 in a number of sub-basins, and the initial abstraction decreased accordingly, bringing the basin closer to a rapid response to rainfall. In the simulation, peak runoff at the Hilla Basin outlet reached about 131 m³/s in 2002 compared with 194 m³/s in 2018, and in Diwaniyah 135 compared with 224 m³/s. In light of future climate scenarios, the study projects a divergence between the two basins. In Hilla, the decrease in peak runoff ranged between 2.4% and 15.2% under the moderate scenario, while in Diwaniyah the decrease ranged between 24.5% and 37.4% under the high scenario, with an increase of between 5% and 15% in some cases. These changes result from the combined effect of climate and the basin surface. These results highlight a practical lesson for water resources planners: it is not enough to monitor and forecast rainfall; changes in land cover must be monitored as well, because the expansion of built-up areas, the loss of rangeland, and bare soil increase the speed of runoff and reduce the opportunities for infiltration and groundwater recharge. This is why basin management, rainwater harvesting, and the preservation of vegetation cover are important, as they restore some of the basin’s capacity to retain water. Presented by: Zahraa Hussein Mohammed, Assistant Lecturer Source: Zahraa Hussein Mohammed Aziz (2024). Projections of Climate Changes in Hydrological Regime of the middle Mesopotamian plain