Real-time Cartography in Operational Hydrology
Christophe LIENERT1, Rolf WEINGARTNER2, Lorenz HURNI1
1Institute of Cartography, ETH Zurich, Switzerland,
2Institute of Geography, University of Berne, Switzerland,
The increase of damaging flood events in recent times demands for enhanced monitoring capabilities in operational hydrology. Indeed, a working monitoring infrastructure can help to detect at an early stage a looming flood event and may improve the immediate preparedness to anticipate and counter it. However, in order that decision makers can constantly revaluate actual hydrological situations by comparing and retracing them, easy to grasp data and data visualizations must be readily available in real-time. Translating real-time requirements of hydrology into cartography implies that new cartographic concepts have to be examined. Up to the present, cartographic map production work steps were mostly accomplished off-line, with human supervision. For a real-time cartographic application, acquisition, storage, processing, visualization and archiving of data must be achieved on-line and with the highest degree of automation possible.
The present paper outlines a prototype application which features three different visualization layers. Particularly the first of these layers takes up these new cartographic concepts by letting users explore the most actual hydrological situation of a catchment. A series of functions have to be devised for automatic and repeated operations on different data models. Initially, the data must be acquired from the data providers, checked for their quality and deposited in a transaction-oriented database from where it is exported for cartographic processing. Geometric, semantic-topological and temporal properties of real-time date have to be linked with geo-referenced base data and rule-based cartographic design is then to be applied. Automatic insertion of new data into, and removal out of, the transaction-oriented system is accomplished according to a “first-in-first-out” principle. Old, processed data is moved and archived in an analysis-oriented system. For all these steps, error handling must be granted high priority. The second layer allows a user to retrace the hydrological developments on the event-scale from a chosen moment up to the present. Methodically, animations and multi-views will be applied to visualize developments and different development stages. The third prototype layer offers functionalities to compare real-time data with historical data deposited in the analysis-oriented archive. That way, users may instantaneously classify real-time data and learn from former events and experiences. Historical data, if resembling actual data, is retrieved from the warehouse and re-visualized, along with statistical and graphical information. The methodical challenge of modelling historical data is to meaningfully select search keys, indexing them and provide fast retrieval.