Dutch title: Voorspelling en beheer van de overstromingsdebieten in de waterwegen met behulp van satellietgegevens en de toepassing van een hydrologisch simulatiemodel
Parent project: Research action SPSD-I: Sustainable management of the North Sea, more
Reference no: T4/DD/30
Period: December 1997 till June 1998
The goal of this study consists in working out a mathematical model coupled hydrology-hydraulics making it possible to stimulate the relations rain-flows in a catchment area as well as the impact of any hydraulic installation on the flood discharges. The model would make it possible to prevent and manage the river flows and would be applicable to any catchment area and particularly to the basins managed by the General Management of the Natural resources and the Environment (DGRNE - Région Wallonne).
The formation of the flood discharges in a basin depends on a complex number of hydrological processes varying in space and time according to the space and temporal distribution of the precipitation observed on the ground, the occupation of the ground obtained by remote sensing, its moisture content as well as topography and nature of the grounds.
The majority of the models currently used are global models, which use average values for the weather data and for the physical characteristics of the catchment area. On the other hand, the model that we propose is a distributed model. The distributed models take account of the space variability of the particular characteristics of the basin, the variations in intensity in space and time of precipitation and thus allow a more fundamental representation of the hydrological processes. Moreover, these models are much less subjected to the problems of calibration and extrapolation met in the global models; they can thus be more easily applied to various basins.
The model will have to be able to simulate the flows on the different kinds of grounds but also the flows within the river, this in order to be able to integrate any hydraulic installation in the river such as a device of pumping or storage of water. The model developed these last years in our laboratory takes account of the spatial distribution of the physiographical characteristics of the basins but gives only one total response of the basin to its discharge system. In order to take into account any hydraulic installation necessary to a good management of the basin, the model will be improved and a new approach based on a representation of the basin by an interconnected system of hydrological and hydraulic components will be followed.
The working time scale will be set to one hour (the majority of the current models works on a daily base). This analysis on a one-hour basis is absolutely necessary to a realistic management of the basins of small size, which present a fast response to the rainy events, such catchment are precisely managed by the DGRNE.
The hydrographic network and the fields of streaming in the basin will be obtained by processing of the digital elevation models (DEM). The occupation of the ground will be obtained by remote sensing; after being adapted and supplemented, it will be then integrated into the digital elevation models and will be used as source data in the model.
Moreover, by expressing the hydrological parameters according to the occupation of the grounds, it will become possible to rationally evaluate the impacts of modifications of the use of these grounds on the mode of the rivers. The model will also allow an easy delimitation of the basins and a determination of possible storage areas in order to help the manager to propose solutions in flood problems.
User-friendly software will be developed in partnership with the engineers of the DGRNE and Electrabel, which will follow the project. This will allow an optimal transfer of the technology developed within the laboratory. Moreover, these people will be able to periodically refresh the data corning from remote sensing for a good use of the program.
The managers of the Coo hydroelectric power station plain to turn their installation to good account during extreme rainfalls by using the water volume of the station to stock flood. A concrete application of such a model will make it possible to quantify the effect of such installation on flood discharges in the valleys of Ourthe and Amblève.
The development of such a tool would make it possible to identify the key problems, to evaluate the effect of any installation on flood discharges, to define work best adapted to reduce these effects and finally, to help the public for a better integrated management of the catchment areas. Moreover, it is significant to note that this model would be also applicable within the framework of the contracts of rivers undertaken and follow-ups by the DGRNE. Let us notice finally that it would be also possible to transpose the method and the software to other hydrographic zones apart from the only basins of the Région Wallonne (for example in South America and Asia, and this possibly in partnership with Electrabel, manager of several hydraulic installations in these areas).