The impact of climate and land changes on a runoff parameter: Al-Adhaim basin in Iraq

This research aims to assess the impact of climate change and land use changes on the CN in the Al-Adhaim River Basin, one of the most important tributaries of the Tigris River in Iraq and its environmental and economic importance for passing through important agricultural areas. NASA, remote sensing images within GIS, and HEC-GeoHMS software were used to analyze changes in land cover and soil types during the period 2017–2023. The results showed an increase in CN values ranging from 6 to 14.4 due to forest shrinkage (from 0.11% to 0.06%), agricultural expansion (from 30% to 34%), and urbanization (from 2.4% to 3.2%), which led to increased surface runoff and flood risk. The highest values (85–98) were concentrated in areas with clayey and saline soils near the riverbed, while the lowest values (55–65) appeared in the northern regions with higher absorption capacity. So, Al-Adhaim Basin has become increasingly vulnerable to hydrological stresses due to climate and human changes, necessitating the adoption of integrated water resource management policies. The practical value of this study lies in supporting plans to establish floodwater storage projects, enhance urban drainage networks, and reforestation programs to reduce runoff and desertification.