What are the territorial challenges ? Why is transnational cooperation is necessary ?
Climate change and rapid urbanisation will result in increasing water management problems in urban areas through this century. Urban areas in North-Western Europe are especially vulnerable due their high population densities and high concentration industrial and infrastructural assets. The most important challenge is to obtain reliable rainfall data and prediction at the urban scale, which is currently unavailable. Meanwhile, heavy rainfall is a main cause of water-related problems in urban areas: a UK Review 2007 states that about two thirds of the flood damage in urban areas was caused by pluvial flooding. The objectives of the RAINGAIN project are to obtain detailed rainfall data at the urban scale, to use these data to model and analyse urban flooding and to implement the use of rainfall and flood data in urban water management practice to make cities more resilient to local rainfall-induced floods.
Weather radars are the only measuring devices that provide estimates of rainfall in time and space; existing devices like rain gauges measure only point rainfall. In the RAINGAIN project, 4 different types of radar techniques will be tested in 4 pilot locations. The pilots are chosen based on the high ambitions of responsible water authorities to improve urban pluvial flood management and because each has specific expertise that others will learn from, such as previous experiences with radars and flood models and different choices in the type of solutions for flood protection. New radar technology for rainfall measurement will be installed, tested and implemented for prediction in pilot locations to demonstrate the technology’s applicability in practice. Local authorities will be involved and trained during international meetings and workshops to incorporate the use of the data and knowledge in their operations. Project deliverables will enable other EU countries to have access to this integrated technology.
What is innovative about this project ?
Current techniques for rainfall observation are unable to measure and predict rainfall at sufficiently detailed spatial and temporal scales to match the fast hydrological processes and high spatial variety in urban areas. Consequently, there is an imminent need to implement new techniques that can accurately measure and predict rainfall and resulting pluvial flooding in urban areas. In the RAINGAIN project a recent technology of X-band radars will be tested for application in urban water management. Their higher frequency compared to classical S-band and C-band radars allows to increase the effective spatial scale resolution by a factor of about ten (down to hectometre scale), i.e. to increase the number of precipitation data pixels by a factor of a hundred. X-band radars thus provide the equivalent of a network of hundreds of traditional rain gauges. Furthermore, these radars are lighter and less expensive, and are therefore manageable and affordable to local water authorities.
Paris and Rotterdam will acquire new polarimetric X-band radars (respectively with pulsed and with continuous emissions), whereas Leuven will test a recently acquired (non polarimetric) X-band radar and in the UK, Met Office will improve signals from the upgraded (C-Band) radars by so called ”super resolution” to provide higher spatial and temporal resolution, close to what is needed for applications in the urban environment. This is the first time urban rainfall radars will be used and implemented in urban water management. By coupling these detailed rainfall data with flood models, this project covers a major gap in knowledge and technology, as it deals with a type of flooding that, up to the present, is not well understood. Additionally, the methodologies are innovative in themselves, because their set-up allows flexibility to cope with the challenges of practical implementation by local water authorities such as time efficiency and data scarcity.
