It is convention to assign the rainfall to the beginning of the timestep under consideration. This convention is applied in ReFH2 to both the antecedent and event data used when modelling an observed event. For event data, for example, the rainfall assigned to 10:00am is the rain that fell between 10:00am and 11:00am.
When importing event rainfall data ReFH2 provides the option to shift the data. If this is selected then the rainfall should be assigned to the previous timestep. For example, if the rainfall assigned to 10:00am represents the rain that fell between 09:00am and 10:00am then, on selecting the option, the rainfall should be assigned to 09:00am, to be consistent with convention.
A bug has been identified in ReFH2 when this option is selected; instead of assigning data to the previous timestep the initial timestep is set to be midnight of the date associated with the first timestep.
This bug will be fixed within the next ReFH2 release. In the intervening period we recommend amending the input data so that it is aligned with convention (by assigning rainfall to the previous timestep) or amending the time associated with the output data appropriately.