The performance of ReFH 2 across both permeable and impermeable catchments within the NRFA Peak Flows dataset is evaluated in Section 6 of the ReFH 2 Technical Guidance. This demonstrates that the ReFH 2 permeable catchment performance is a considerable improvement on the original ReFH method. This is particularly the case when used with the FEH13 rainfall model, where performance is comparable to the current FEH statistical method.
Permeable catchments are some of the most challenging catchments and it is recommended that more than one method is used for design flood estimation. Furthermore, when applying methods users should consider issues such as whether the topographic and groundwater catchment boundaries are coincident and whether discrete features such as spring lines strongly influence flows.