Expert system: System conditions in Torrent Catchments

The proposed research project will contribute to the assessment of the extent of flood events in torrent catchment areas. The methods that have so far been used to determine the extent of floods with a specific recurrence probability (extrapolation of records, estimations) do neither consider different system conditions in the torrent catchment area at the beginning of a precipitation event nor the possibility of changing climatic conditions. The proposed research project plans to pursue a new, so far little developed way for the estimation of flood events. It aims at establishing the prototype of an expert system which infers the flood-controlling system conditions in a catchment area (e.g. soil dry, saturated, frozen, vegetation with fully developed foilage, pastured) at the beginning of a precipitation event. The current system conditions in a catchment area are defined by means of rules of the form of "if A, then B" on the basis of the characteristics of the catchment (geology, topography, soil and vegetation), information on landuse, and precipitation as well as temperature records. The classification of the system conditions is based on fuzzy-logic methods in order to take into account that there are no sharp boundaries between different types of system conditions, and that the resulting discharge behaviour changes continuously. For programming the expert system, the fuzzy-logic toolbox of the programme MATLAB is used. The necessary spatial data (concerning geology, topography, soil, vegetation, average conditions of the soil and vegetation system, precipitation distribution, temperature distribution) is provided by means of the geographical information system ArcGIS. In order to determine the discharge resulting from of the current system conditions in a catchment area, the expert system needs to be combined with a discharge model. To be able to assess the influence of the discharge modelling on the overall results, and thus to enable conclusions on the quality of the expert system, two different flood models (PROMAB, HQsim), which have successfully been applied in Alpine torrent catchment areas, are used in the initial stage. The prototype of the expert system will be tested in small Alpine catchment areas (< 10 km) with a good availability of data. The proposed method allows to calculate different flood peak scenarios for each precipitation amount respectively intensity, for different system conditions in the catchment area. Thus the expert user can obtain information on the extent of possible flood events for the catchment area, and choose from a range of system dependent options as a basis for the planning of measures.