Grid-based System for Flood Forecasting
Abstract:
This paper presents our experience and current status of a Collaborative Problem Solving Environment for Flood Forecasting under development as a part of the IST CROSSGRID project. Over the past few years, floods have caused severe damages throughout the world. Most of the Europe was heavily threatened. Therefore, modeling and simulation of flood forecasting in order to predict and to make necessary prevention became very important matter. The environment described here uses Grid technology to interconnect experts, data and computation resources needed for quick and correct flood management decisions. In the core of the system lies a coupled set of simulation models used to predict precipitation and temperature, hydrological river status and hydraulic events in target areas. The environment and its web-based interface also provides some basic communication tools, enabling its users to cooperate. Virtual Organization for Flood Forecasting, using this environment may consis of several cycle providers, storage providers, end users, experts and developers.
Forecasting of flood events requires quantitative precipitation forecasts as well as forecasting of temperature (to determine snow accumulation/melting). The system makes use of the ALADIN/SLOVAKIA model. ALADIN is a LAM (Limited Area Model) developed jointly by Meteo France and cooperating countries. In the next stage we are using several hydrological simulation models, depending on conditions and needs which will be applied model for which situation and territory, they can be also used in combined way. For hydraulic predictions, FESWMS (Finite Element Surface-Water Modeling System) Flo2DH is used, which is a 2D hydrodynamic, depth averaged, free surface, finite element model. Flo2DH computes water surface elevations and flow velocities for both super- and sub-critical flow at nodal points in a finite element mesh representing a body of water (such as a river, harbor, or estuary). imulation of floods is very computation-expensive. Several days of CPU-time may be needed to simulate large areas. For critical situations, e.g. when a coming flood is simulated in order to predict which areas will be threatened, and to make necessary prevention, long computation times are unacceptable. Therefore, FESWMS Flo2DH was parallelized in order to achieve better performance.
The storage space for simulation outputs and direct measurements used by the application is provided by II SAS. Hourly outputs of meteorological simulation, hydrographs provided by the hydrological part of the cascade and selected hydraulic outputs will be stored. The storage will also hold configuration files for the simulations and some other resources, needed to operate the application. The stored files are accessible through standard Grid tools used in the CrossGrid testbed. We are also working on a common description scheme for these files and a way to store the metadata in a Grid-aware database system. The metadata structure will include detailed information about origin of the file, time of its creation, the person who actually created it, etc. In case the file is the output of a simulation, the metadata will also contain names of the input files, model executable and configuration files.
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