This thesis deals with the management of the urban flood as a result of the opening of the new path of Østerå in Aalborg.

Firstly, a flood risk assessment to evaluate the hydraulic consequences of the new path and to estimate the likelihood of flooding has been made by implementing the new channel in Mike Urban 2017 software. To provide the initial conditions for the model, an observed data of Østerå, Limfjord and historical rain series data is used in order to improve the performance of the model. The result shows that the opening of the new channel has a positive effect on the flood cost and has a significant impact on the project area, especially by decreasing the flooded-area in the residential district of Karolinelund.
Next, based on the assessment result, it has been investigated whether it is possible to provide a sustainable approach by implementing a control activities in order to handle the flood caused by the runoff-flow from the residential area. Two different scenarios have been implemented in Mike Urban Model, simulated and discussed. The first scenario is based on a passive control and the second one is based on an active (local) control.
It has been found that both scenarios are sufficiently capable of reducing the flood and decrease the total flood cost.

Finally, the solutions are applied to the future condition to investigate the climate change impacts on the project area. From the result, it has been concluded that it is possible to handle the runoff water from the surrounding catchment through the implementation of the control scenarios in both the current and future condition.