impacts. The MUFFIN project includes partners at different levels of water management (Figure 2). It will set up âtest benchesâ in à lborg, Helsinki, Rotterdam and ...
Photo: Johanna Sörensen
MUFFIN -
MULTI-SCALE URBAN FLOOD FORECASTING
Pluvial urban flooding, caused by extreme rainfall intensities combined with a large fraction of impervious surface and limited capacity of storm water sewer systems, is a major societal hazard today. The problems are anticipated to increase, as higher intensity rainfalls are expected in a warmer atmosphere containing more precipitable water. Developing systems for urban flood forecasting and early warning is a key requirement for keeping cities secure and sustainable with respect to flooding hazards and mitigating flood impacts. Accurate urban flood simulation and forecasting require a very short time step (minutes) and a very high spatial resolution of both rainfall input (hundreds of meters) and the description of the urban environment (meters). Designing, constructing and maintaining such locally tailored urban flood forecasting systems is very resource-demanding. New hydrological model development, real time monitoring of key hydrological processes, and increase in computational power have made it possible to simulate the extent of urban floods in real time on catchment or city scales. The precision and validity of precipitation observations in cities, with still more accurate short-term precipitation forecasts of extreme rainfall, prompt new possibilities to simulate the risk of an impending urban flooding. Even with less accuracy than in local systems, urban flood forecasts from large-scale systems may be useful for end-users if well interpreted and presented.
The MUFFIN project includes partners at different levels of water management (Figure 2). It will set up “test benches” in Ålborg, Helsinki, Rotterdam and Stockholm to explore different ways to forecast floods in urban basins and answer questions such as the following: • The rainfall forecast: What is the impact of resolution in time and space? Which types of forecasts are most suitable? What accuracy is attainable with respect to time, place and intensity of short-duration extremes? • The hydrology/hydraulics model: What are the different characteristics in terms of surface and subsurface information required, resource demand for model set-up and calibration, computational power, etc.? What accuracy is attainable with respect to time, place and intensity of short-duration extremes? • The end user value: How early must a flood alert be issued, and what spatial level of detail is useful for different end-users? What is the value of largescale forecasts in cities lacking a local forecasting system?
Photo: Johanna Sörensen Figure 1 Intense precipitaon in urban Copenhagen, August 2014
Figure 2 Partners, structure and division of responsibilies in MUFFIN
A key aspect of the project that end-users will be invited to join the project and be involved from start to finish in order to ensure the most useful outcome possible. Innovative means of interpreting, processing and communicating the forecasts to provide added value for the end-users will be developed. Key scientific outcomes are new knowledge about small-scale precipitation extremes, their predictability and limitations of urban flood forecasting at different scales. In terms of practical solutions, new and improved operational tools for urban flood forecasting in Europe will be developed.
