Section 11 Backward Compatibility

11.1 Backward Compatibility to the 2020-10 Release

The following changes have been made to the default settings from build 2020-10-AF. Some of these have specific commands to revert behaviour, for others these can be reverted by setting defaults to pre 2023. These changes are summarised in Table 11.1 below. Changes specific to models with Sub-Grid Sampling (SGS) are summarised in Table 11.2 and changes specific to models with SGS and High Resolution Outputs in Table 11.3.

Table 11.1: Changes in Defaults
Description of Change Section Backward Compatibility Command
Change to quadtree handling of inertial parallel to boundary Section 5.4 Quadtree BC Parallel Inertia Approach == Method A
Upper limiting Manning’s n in Wu turbulence calculation Section 4.7.1 Viscosity Coefficient == \(\langle\)C3D, C2D, 99\(\rangle\)
Duplicate Materials IDs Section 2.7.2 No specific command - Defaults == Pre 2023
Duplicate Soil IDs Section 2.7.3 No specific command - Defaults == Pre 2023
Duplicate SA Boundaries Section 5.9.2 No specific command - Defaults == Pre 2023
HPC Weir Approach Section 4.2 HPC Weir Approach == Method A
HPC SX Momentum Section 5.2 HPC SX Momentum Approach == Method A
HPC Boundary Approach Section 5.6 HPC Boundary Approach == Method B
Initial Moisture and Green-Ampt infiltration Section 2.3.9 No specific command - Defaults == Pre 2023
Drop Support for 2d_bc QT Point Boundaries (Classic/HPC) Section 5.7 No specific command - Defaults == Pre 2023
Drop Support for 2d_bc HQ Point Boundaries (Classic/HPC/Quadtree) Section 5.8 No specific command - Defaults == Pre 2023
Table 11.2: Changes in Defaults - SGS Models
Description of Change Section Backward Compatibility Command
SGS Approach Section 2.2.2 SGS Approach == Method B
SGS Depth Output Section 2.2.1 SGS Depth Output == Exact
Mapping of partially wet SGS cells Section 2.2.1 SGS Map Extent Full == h
Table 11.3: Changes in Defaults - High Resolution Outputs
Description of Change Section Backward Compatibility Command
High Resolution raster output interpolation method Section 2.2.5 HR Interpolation Approach == Method A
High resolution thin breaklines Section 2.2.6 HR Thin Z Line Output Adjustment == OFF

As always, it is recommended when switching to a new Build with an established model that test runs be carried out and comparisons made between the old and new Builds (subtracting the two maximum water level (h) data sets and reviewing any differences is an easy way to do this). If you have any queries on the comparison outcomes, require clarification or more detail on any of the points below, please email .