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Track: Water Resources
Ubo Pakes
Rijkswaterstaat RIZA
PO Box 9072
Arnhem, 6800 ED
THE NETHERLANDS
Telephone: 31-26-3688911
Fax: 31-26-3688678
R. van der Veen, M. Zeeman, B. Schutte (RIZA), J.A.F. van Essen (RIZA)
The Use of GIS for One-Dimensional River Modeling of Large Dutch Rivers
The Netherlands has a very intense relationship with the Rhine and Meuse rivers. In the densely populated country a balance has to be found between flood protection, shipping, nature, industry, and recreation. The recent floods have made it very clear that the rivers still have powerful and threatening natural features. To find a balance between all the functions of the river, one and two dimensional models are being used to assess possible measures in the river system. In order to build one-dimensional models based on the SOBEK software package and to keep them up to date, a GIS-based system has been developed. The system uses data from different sources and in different formats on a 1:500 scale. Among other types of information on elevation, lakes, dikes, flow areas and storage areas, and vegetation structure are required. Using results from the two-dimensional model WAQUA, even complex flow situations are relatively easy to implement in a one-dimensional model. The source data is converted into
ArcInfo format for input for the calculations. Using ARCGRID functions, an AML-based application computes the geometric information for the main section, the river bank section and the floodplain. For every calculation a selection is made of appropriate grid cells. These are used to calculate the flow with storage width at every level, taking into account the spatial variation of the river system. The calculations for the main section take place on a more detailed scale than for the other parts of the cross section. The output from the application are files that can be used directly by SOBEK. This new way of modeling the river is completed with a system that can be used for a visual check and for presentation of the model. The system gives insight into both the river as a system and the way it is modeled. In combination with other information used by the model, the user gets a quick overview of all the data used in the model. The process results in a very robust and consistent way of modeling in
which changes are easy to apply in relatively little time. After calibration the model results meet the high standards required for flood prediction calculations. The use of GIS allows for easy updates of the data. The way the model is visualized makes it possible even for non-river engineers to understand the way the river has been modeled. It allows the user to keep models-up-to date with regard to changes that take place in the river system. The current development of a central GIS database for river modeling and research on further automation will make the method of modeling even more efficient.
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