Background
Overland flow generated by intense rainfall is a major driver of urban flooding. However, direct observations of overland flow are rare, making it difficult to quantify its magnitude and spatial characteristics, particularly for extreme events.
Objective & Method
This thesis will investigate a novel approach for estimating extreme overland flow in urban catchments. The work will use the DDD rainfall-runoff model to simulate long-term time series of overland flow for the Lye2 urban catchment. Extreme value analysis will then be applied to derive design overland flow estimates for selected return periods.
The estimated design flows will be used as input to an existing two-dimensional hydraulic model to map flood pathways, water depths, flow velocities, and the hazard indicator depth × velocity. The results will be compared with the recommended conventional approach (veileder NVE 2/2023) based on design rainfall events.
Expected outcomes
- Estimation of design overland flow values using hydrological modelling and extreme value analysis.
- Hazard mapping of urban flooding using hydraulic modelling.
- Evaluation of a new flow-based methodology against traditional rainfall-based approaches.
- optionally: Recommendations for urban flood risk assessment and stormwater management.
This project offers an opportunity to work at the interface of hydrology, hydraulics, and urban flood risk management, while contributing to the development of innovative methods for assessing flood hazards in urban areas in Norway.