Climate change and urbanization have significantly increased the frequency and intensity of urban floods and droughts in numerous places. The one selected area for study representing semi-arid urban environments is Bnaslawa, a sub-district inside the rapidly expanding urban region of Erbil, situated in the Kurdistan Region of Iraq. The study integrates both geographical and hydrological modelling to define the efficacy of, including green roofs and cisterns, in lowering stormwater runoff and the risk of floods. To identify the best locations, the team used a best management practice siting approach that considered slope, land use, impermeable surfaces, hydrologic soil group, groundwater depth, and proximity to buildings, roads, and waterways. There are 1.35 km2 of potential locations for green roof installation. In residential neighborhoods that had significant rooftop interaction and poor drainage infrastructure, rain barrels were distributed simultaneously. The EPA Storm Water Management Model was used to assess hydrological performance according to development storms with return periods of 2, 5, 10, 25, and 45 years. Green roofs can hold up to 155,670 m3 of stormwater and reduce peak flow by 10-12% during low- and moderate-intensity storms, according to the study. Cisterns also help reduce runoff in select places. The best management practices-integrated siting scenario boosted the system's resilience, delayed peak flow, and lowered overall runoff volume by 35-75 % during mild events. Overall, the findings show that including green infrastructure into a plan can significantly improve a city's flood management capacity while also providing a beneficial foundation for nature-based use. These solutions can be applied to future urban development and stormwater control.