ReFH 2.3 supports two internal modelling engines: one that provides backwards compatibility with ReFH 2.2 (“the ReFH 2.2 model”) and one with the latest model engine and new features, such as observed rainfall and climate change factor modelling (“the ReFH 2.3 model”).

The ReFH 2.3 model requires the new BFIHOST19 catchment descriptors, available in the latest version of the FEH Web Service catchment or point XML files. Please see How do I enable the ReFH2.3 Model?

If you load an earlier version XML file (pre-November 2019), or an existing project saved in the ReFH 2.2 software, ReFH 2 will only run the ReFH 2.2 model.

The modelling screen indicates whether the ReFH 2.2 or ReFH 2.3 model is being used:

The catchment descriptors tab highlights when BFIHOST19 is not available:

The climate change factor and observed events are only available for the ReFH 2.3 model; consequently the buttons to use these features are greyed out for the ReFH 2.2 model. Please see Why are the climate change factor and observed rainfall buttons greyed out?