In the Layers Control Panel, select the Grid Extents layer and right-click.Right-click and select Delete Vertex from the menu. Click once in the interior of the polygon to exit the Add Vertex mode. Move to another location on the boundary to add a new vertex.
![pcswmm 2d urban flood modeling pcswmm 2d urban flood modeling](https://i.ytimg.com/vi/PJalVRYO3eQ/maxresdefault.jpg)
The vertex may be moved by dragging it to the new location. The cursor will appear as a box with arrows moving inward. Move the cursor over the polygon boundary. A red dot will appear next to the cursor. Right-click over the polygon and select Insert Vertex from the menu.Hold the left button down, drag the vertex to a new location and release.
![pcswmm 2d urban flood modeling pcswmm 2d urban flood modeling](https://i.pinimg.com/originals/b9/9d/f2/b99df2d757f709fc57e1bb6cfd1c0209.jpg)
After a polygon is selected, it may be edited by three techniques:
![pcswmm 2d urban flood modeling pcswmm 2d urban flood modeling](https://i.ytimg.com/vi/bAoGyM5S9bo/maxresdefault.jpg)
Then edit the polygon by adding and adjusting the vertices. One polygon drawing technique is to “rough in” the area with a few vertices.
![pcswmm 2d urban flood modeling pcswmm 2d urban flood modeling](https://i.ytimg.com/vi/V9IFCz4B3ho/maxresdefault.jpg)
Ive done a complete urban model for testing (fun) at home in XPSWMM utilizing rain on grid with a interconnected underground SS network that would take inflow from the surface. The reality is most SS networks are designed for ARI’s that lower than that used for inundation mapping.