QGIS ReFH2 to TUFLOW: Difference between revisions

FEH2022 is the most up-to-date Depth Duration Frequency (DDF) model for generating design rainfall hyetographs. CEH recommend the use of FEH2022, which supersedes the FEH2013 DDF model and therefore the 1999 method . In order to generate the design rainfall, the user obtains FEH2022 design rainfall depths from the FEH Web Service at https://fehweb.ceh.ac.uk for pre-defined return period/duration combinations. This requires a log on and user credits to purchase the data for the desired location. Data is available at a river catchment scale and as a point value. Both of these provide XML containing the rainfall depths. This is then imported into the ReFH2 software to generate hyetographs based on Flood Studies Report (FSR)/FEH approaches. The current version of ReFH2 (2.3) model supports use of both the 2013 and 2022 DDF models. Version 2.2 only supports the 2013 DDF model, an error message will be generated should the user try to use the 2022 DDF rainfall with the 2.2 ReFH2 model.

In order to use the tool, ReFH2 Version 2.27059.19021 or later, must be installed on the local machine which can be downloaded from the following link (https://www.hydrosolutions.co.uk/software/refh-2/refh2_download/). The ReFH2 software requires the relevant local licence. Network licencing may be available in the future.

Once the relevant location specific data has been input, then the user should first pick the ReFH2 model that they would like to use. The 'legacy' 2.2 and newer 2.3 ReFH2 models are available. In order to use the ReFH2.3 model ReFH2.3+ descriptor files, containing a new BFIHOST19 parameter, are required. If ReFH2.2 parameters are used with the ReFH2.3 engine, an error message will be flagged. The latest Catchment Descriptors contain information for the 2022 DDF model as well as the 2013 DDF model. The 2022 DDF model is recommended by CEH. However, the 2022 DDF parameters cannot be used with the legacy 2.2 ReFH2 model. Both 2013 and 2022 DDF parameters can be used with the 2.3 ReFH2 model by specifying the desired option in the FEH Rainfall model section. The default options are to use the 2022 DDF model witht he 2.3 ReFH2 model.

A second csv file is the processed data for the output of interest (ie,i.e. net rainfall or direct runoff) for the return periods of interest. This file is named as the above raw file but has the suffix ‘_TUFLOW’. As well as only included the selected output time-series, the time format is converted from HH:MM:SS to hours which is the format used by TUFLOW. The first value in the time series is also set to Zero to be valid within a TUFLOW simulation.

These files can then be merged together by the user where multiple boundary conditions are required in the model domain (future developments will allow this to be done automatically, as well as allow global rainfall to be applied) and moved to the relevant TUFLOW model folders to be used within simulations.