Automatic data completion

Grids: OPtional: During model initialization, input grids (e.g. land use) can be compared cell by cell to the corresponding master grid (which is the zone or sub-basin grid). If there is a valid value in the master grid but a nodata-value in the other grid, the nodata value is replaced by the value of another cell using the nearest neighbor method. Thus, input "holes" in the input grids can be filled with valid values. If the hole is too big, the model doesn't fill it but stops execution to prevent absurd values.

WaSiM supports the derivation of some model input grids. Input grids like slope, aspect and topographic factor can be generated internally from the DEM.

Missing data in time series: WaSiM takes only valid values into account when doing meteorologic interpolations. As long as at least one station provides valid values, the interpolations will work. An exception are time steps with no valid input data at all. In such cases, the interpolations are skipped, thus using the values from the last time step for the actual time step again (until a time step with valid values is found)

Some meteorologic data can also be derived from existing ones:

• Derivation of global radiation from relative sunshine duration
• Derivation of relative sunshine duration from radiation
• Derivation of vapor pressure from air humidity
• Derivation of air humidity from vapor pressure

Exsample: Relation between relative sunshine duration and relative global radiation (for the metorologic station St. Gallen, Switzerland)