Typologie des modèles de prévision des crues/en

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Background information

The European Union Twinning Project for Turkey entitled "Capacity building to implement the Flood Directive” (TR 10 IB EN 01) involves France as "senior partner" and Romania as "junior Partner".

Hydrography of the turkish watersheds

The following chart gives a representation of the 25 hydrographical turkish basins.

One action conducted for the Turkish Water Directorate is to propose a typology of their watersheds, depending on their hydrological characteristics and on their meteorological regime.

To complete this typology and to continue the mission of advisory of the Turkish Water Directorate, a typology of the simulation models is proposed as follow-up.

This table identifies one or more types of models depending on the main process in each watersheds

Using this table as a LEGO® method

The simulation tools identified in the previous table must be used closely in relation with the characteristics of the sub-basins. Let us take a practical example : given a wide hydrological basin as considered in the Water Framework Directive, we would like to equip it with a set of simulation tools. The method to be used is similar as a LEGO® play-game. We will use it by following the process set-up below:

1. identify elementary bricks, that is to partition the wide basin in a series of homogeneous hydrological sub-basins
2. locate the available meteorological gauging stations on each sub-basin (rain gauging, radar) and if necessary to plan to equip the basin with a sufficient numbers
3. locate the outlet of each sub-basin and verify the presence of a functioning hydrometrical gauging station, able to transmit with an appropriate time step data to a central unit
4. this work on the upstream basins will give us the opportunity to determine the hydrological component of our system. One should see if these basins could be equipped with rain-discharge models (given access to meteorological gauging station as well as hydrometrical gauging station)
5. during the process of sub-basins aggregation, the rain-discharge relation could begin unappropriated because the main process is no more concentration than propagation. A new model should be used to simulate the flood (water level evolution) or better the inundation (plain overflowing)
6. one should identify the existing hydrometrical gauging stations in order to use them as the main measurement network to support numerical modeling
7. downstream, the topography and the bathymetry are generally better known, which allows us using 1D hydraulic models to simulate inundation. This could be completed by hydrological rain-discharge models
8. further downstream, the plain could begin more hydraulically complicated and using more sophisticated models like 1D cell models or 2D models
9. at the sea entrance, the interaction between river discharge and sea conditions : storm surge, wave, necessitates the use or 1D or 2D hydraulic models
10. The two following examples shows the way to implement this LEGO® method.

Example n°1 : coupling rain-discharge models with discharge-discharge model

The two figures illustrate the physical domain (left) and the diagram of the flood forecasting systm.

Some advice on the use of these models

The choice, the installation and the use in operational conditions of these tools should be preceded by the installation of a hydrometric gauging station network, appropriated to each sub-basin. This network should be composed of various measuring device types (liminimeter, pressure sensor, radars, image analysis...) adapted to each site, supported by an efficient transmission network.
The modeling tools should be:

• adapted to the hydrological or hydraulic dynamic of the corresponding sub-basin
• interfaced with real time supplied data from the field
• interfaced with meteorological real time supplied measures or forecasts : rain, snow, wind...
• interfaced with other upstream or lateral hydrological or hydraulic models
• used in deteriorated conditions
• used inside their conditions of use, which must be well assimilated by flood forecasters
• confronted with the real conditions in flood situations: inundated areas, broken works...
• completed with other types of models
• as robust as possible to avoid any crash during crisis situations
• should have been calibrated on the most wide historical flooding event panel
• associated with human machine interface in order to minimize data exploitation time and to give the best realistic representation of the hydrological response for the decision makers

These simulation tools are in fact one of the components of a global architecture of a flood forecasting system. They should be based on the human strengths and abilities of the flood forecasters teams and a first rate hydrometric gauging stations network.

Le créateur de cet article est Jean-Michel Tanguy Note : d'autres personnes peuvent avoir contribué au contenu de cet article, [Consultez l'historique]. Pour d'autres articles de cet auteur, voir ici. Pour un aperçu des contributions de cet auteur, voir ici.