TU Delft is participating in the MUFFIN campaign (Multi-Scale Urban Flood Forecasting: From Local Tailored Systems to a Pan-European Service) aiming to study urban flood forecasting from a multi-scale multi-disciplinary perspective, that is from the point of view of different scientific, technological and social disciplines. TU Delft is represented by the Atmospheric Remote Sensing Group collaborating with fellow-scientific groups in Denmark, Finland and the leading group in Sweden (SMHI) with the aim to develop, implement and test different urban flood forecasting systems in 3 major European cities: Rotterdam (Netherlands), Aalborg (Denmark) and Helsinki (Finland). The key components studied in these experiments are:
1. The role of the rainfall input: both in terms of real-time and in the form of numerical forecasts at different spatial and temporal resolutions.
2. The land-use data and associated information such as imperviousness and soil infiltration capacity and how they impact the hydrological response.
3. The flood forecasting model: either in the form of tailored solutions accounting for local surface/sub-surface flows or from a larger-scale perspective (e.g., integrated basin runoff).
The goals are to specify the requirements in all these 3 key aspects for different end-user categories, to explore the trade-offs between scale, accuracy and end-user value and assess the limits of current state-of-the-art urban flood forecasting systems. A key aspect of the project is active end-user involvement and multi-disciplinary collaboration between different stakeholders.
The main task and responsibility of TU Delft within MUFFIN is to collect high-resolution weather data in Rotterdam to study the spatial organization and dynamics of rainfall over urban areas and perform fundamental research into the science underpinning the measurement and forecasting of heavy localized convective storms.
Significant progress has been achieved in 2017 with the acquiring of many new datasets including:
• The Rotterdam X-band rain radar: 1-min horizontal scans with a range of 30 km and a horizontal resolution of 100m are being transmitted in near real-time to a TUD server (from August onwards).
• The Micro-rain radar (MRR): A MRR has been purchased and installed on the roof of the CiTG building at TUD. It collects vertical profiles of rain rates, reflectivity, liquid water content and particle size distributions at 10 s and 35 m resolution to study the vertical variability of rain from the clouds down to the ground.
• WRF Modelling: the state-of-the art Weather Research and Forecasting software (WRF 3.9) has been set up over Rotterdam and can be used to perform high-resolution numerical weather modelling and forecasting for selected rainfall events. The model has a parent domain of 5 km grid spacing covering the entire BeNeLux region, a second domain of 1 km grid spacing over the Netherlands and a third innermost domain over Rotterdam at 200 m grid spacing and 135 vertical levels. Both single- and double-moment microphysics schemes have been implemented.
• Citizen weather data: Rainfall, temperature, wind and pressure from hundreds of citizen rain gauges in and around Rotterdam are being collected since January 2017.
• Professional 5-min weather data (rainfall, temperature, relative humidity and wind) from 10 TU-Delft operated weather stations in/around the city of Rotterdam to validate the radar rainfall products.
The Rotterdam Radar