The format of the precipitation rate (or net precipitation rate) and evaporation rate can be specified as
· Constant (in time and domain)
· Varying in time, constant in domain
· Varying in time and domain
If specified precipitation/evaporation is selected the precipitation/evaporation ´rates must be positive. If net precipitation is selected and the precipitation rate is negative it will act as evaporation.
For the case with precipitation rate varying in time but constant in domain you have to prepare a data file containing the precipitation rate before you set up the hydrodynamic simulation. The data file must be a time series file (dfs0). The data must cover the complete simulation period. The time step of the input data file does not, however, have to be the same as the time step of the hydrodynamic simulation. A linear interpolation will be applied if the time steps differ.
For the case with precipitation rate varying both in time and domain you have to prepare a data file containing the precipitation rate before you set up the hydrodynamic simulation. The file must be a 2D unstructured data file (dfsu) or a 2D grid data file (dfs2). The area in the data file must cover the model area. If a dfsu-file is used piecewice constant interpolation is used to map the data. If a dfs2-file is used bilinear interpolation is used to map the data. The data must cover the complete simulation period. The time step of the input data file does not, however, have to be the same as the time step of the hydrodynamic simulation. A linear interpolation will be applied if the time steps differ.
For the case with evaporation rate varying in time but constant in domain and for the case with evaporation rate varying both in time and domain the data file needed must be prepared in the same way as described above for the precipitation input.