Monsoon rains cause floods in Viet Nam almost every year, particularly in the city of Da Nang, where the stormy rainfall has brought to almost 600 mm within one day then inundation was catastrophic. Therefore there is an urgent need to mitigate floods what can be achieved by using flood-control reservoirs. So, the main objective of the present work is to evaluate the possibility of mitigating inundations with help of modeling floods and their routing through the reservoir. The virtual water reservoirs are considered in various sites of the Han river. Accordingly, the necessary characteristics are determined on the basis of GIS information.In the work the following tasks were solved: modeling of storm rainfall; modeling scenarios of catastrophic floods on river basin; determination of characteristics for water reservoir; modeling of flood routing through water reservoir; modeling of inundation on Da Nang territory.The results provide a possibility to consider variants of the locations for the location of the flood-control reservoirs and corresponding variants of inundation in the city of Da Nang.