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[[File:Fig1 H sgs.png|700px]]<br>
'''Figure 1 Water level simulation results with SGS. Lefe: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>
On the other hand, the same model running without SGS method creates significantnotably differencedifferent results in the distance of water travelled alongand the gullyarea of inundation on floodplain due to the poor geometry representation.<br>
[[File:Fig2 H nonsgs.png|700px]]<br>
'''Figure 2 Water level simulation results without SGS. Lefe: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>
ThisThese meansexamples indicate the mesh size sensitivities of a SGS model are significantly reduced, and modellerthus modellers are increasingly using coarser mesh at model domainareas far away from the location of interest. However, this has also create a challenge onfor how to output water depth at those coarsecoarser cells. The example below shows even through the 10/20m mesh and the 2.5/5/10/20m mesh models produce similar water level, but the depth map output is much 'smoother'in the model with finer meshes. <br>
[[File:Fig3 D sgs zoom.png|700px]]<br>
'''Figure 3 Water depth simulation results with SGS. Lefe: 2.5/5/10/20m Quadtree model. Right: 10/20m Quadtree model.'''<br><br>
In TUFLOW, the depth output is interpolated from the nearest cell centre and cell corners surrounding the output grid. The interpolated depth may not perfectly represent the actual depth, since TUFLOW doesn't store the under laying DEM value at the moment. <br>
map output need to "remap" the water level in large Quadtree cells to a DEM with much finer resolution. While we are developing high resolution SGS output in the future release to address this issue, we have also added a new functionality in the [[ASC_to_ASC|ASC_to_ASC]] utility to 'remap' a water level grid to a finer DEM grid. This page introduce how to use the ASC_to_ASC remap function, and also discuss the limitation of the method.
=Base Case=
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