Using ReFH2 to Generate TUFLOW Boundary Inputs: Difference between revisions
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The catchment descriptors (BFIHOST, DPLBAR, DPSBAR, SAAR, PROPWET and Area) can all be edited should a sensitivity analysis be required.
The model parameters section allows the user to specify the seasonality and other parameters, again for sensitivity analysis. Changing the seasonility will change the seasonal correction factor for the rainfall.
The urbanisation tab allows the user to estimate the impact of urbanisation for catchments as well as greenfield and post development peak runoff rates for development sites.
The grids can then be exported to csv using the ‘Export Grid’ option. This exports the time-varying grids for all return periods and all design outputs.
The relevant data can then be copied into the TUFLOW bc_dbase folder and referenced by the bc_dbase.csv file as appropriate (see Module 08 for an example of applying direct rainfall boundary conditions for example).
The gross design rainfall or total net rainfall can be applied to directly to the 2D domain using a 2D_RF polygon to distribute the rainfall. Multiple RF polygons can be used to spatially distribute the rainfall if required.
The total runoff (or rainfall) can be applied directly to a 2D_SA polygon, to apply the inflow to an area of the 2D mesh. There are a number of options for distributing flows in this instance, these are:-
<ol>
<li> • Flow is distributed firstly to the lowest cell and then to the wet cells,
<li> • Distributed to all 2D cells connecting to 1D pits,
<li> • Distributed to all cells equally,
<li> • Distributed using streamlines to define watercourses.
</ol>
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Only distributing to all cells equally represents the surface water mechanism which routes flow from the point it falls, the other approaches work on the assumption that the flow ends up either at the lowest cells, at 1D pits or within channels within the model domain.
It is also possible to apply the total runoff to a 1D or 2D point or line using the 1D_BC or 2D_BC layers. The user can, if desired, split the total runoff by applying the direct runoff component to one model location and the baseflow component to another location.
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=Using TUFLOW Events=
In most applications there will be a requirement to run a number of return period design events, potentially with a number of different durations. TUFLOW’s event options makes the management of these simulations a simpler process. TUFLOW’s event management structure uses a variety of wildcard characters in the TCF file and the boundary condition database for event inputs. The wildcards are replaced with user defined event specific acronyms when a simulation is run from a batch file. This will significantly reduce the number of repetitive files required to execute a project. TUFLOW event management is shown in the following image.
TUFLOW’s event management will be of use when running multiple return periods and durations events from ReFH2. Currently a single CSV file will be generated for a number of return periods from the ReFH2 software. Where multiple durations are used, this will generate multiple csv files. Each of these can be defined as a separate source csv file. For instance, in the bc_dbase file we can have the following where _Duration_ is the wildcard to specify the individual csv files references the different return period hyetographs for each duration.
The wildcard also works on column 2 as well. So we can use this to use the return period as specified in the batch file to read the relevant column from a csv file exported directly from ReFH2.
For example, in the file directly exported from ReFH2, the 1 year net rainfall column is called “Total net rain mm (1 year) - as 100% rural model”. We can set column 2 to look for the ‘Total net rain mm (ARI) – as 100% rural model’ bc_dbase setup to read the relevant net rainfall column for the return period of interest based on the ARI wildcard. Note: The exported csv file has time in HH:MM:SS. We would need to convert this to hours. Also the exported rainfall profiles do not have the first value set to 0mm. Do we just add a dummy line with 0mm here?.
Once the bc_base has been set up then a .tef file can be generated which populates the ARI variable above with the relevant ARI for the specific question. The tef file also creates anew new output folder for each return period.
The .tcf file can be named accordingly for example, Dummy_M01_~e1~_001.tcf, and the batch file commands used to set the ~e1~ value.
Start "Tuflow" /wait ".. \2018-03\TUFLOW_iSP_w64.exe" -e1 1yr "Dummy_m01_~e1~_001.tcf"
Start "Tuflow" /wait "..\2018-03\TUFLOW_iSP_w64.exe" -e1 2yr "Dummy_m01_~e1~_001.tcf"
Start "Tuflow" /wait "..s\2018-03\TUFLOW_iSP_w64.exe" -e1 5yr "Dummy_m01_~e1~_001.tcf"
This will then run the 3 return periods (1yr, 2yr and 5 year).
=Summary=
This post provides instructions of how to obtain direct rainfall and inflow inputs from the ReFH2 software for use within a TUFLOW model. This requires the input of data from the FEH2013 website and the selection of the appropriate return period, duration combinations of which the user is interested. This outputs the time-varying rainfall and total runoff (as well as runoff contributions) which can be exported for use within TUFLOW. Future development in this area will look to automate some of this process with a plugin.
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