TUFLOW 1D Channels and Hydraulic Structures: Difference between revisions

For irregular shaped culverts and channels with(set anas I typein crossthe sectionType attribute of the 1d_nwk layer), anthe alternativeonly available method to simulatemodel blockage is by applyingusing athe Skew (in degrees) attribute in the 1d_xs layer. This reduces the effective flow width of the cross section by rotating it relative to the direction of flow and can be used to approximate reduced capacity due to debris or structural blockage.

A skew angle of 0 means the cross section is aligned with the flow. As the angle increases, the effective width is reduced. For example, a skew of 4560 degrees results results in a square root of 250% reduction in width (as cos(60) 45= degrees0.5). While this does reduce conveyance,the effective width of the relationshipstructure, isit notisn’t oneexpected to onesee withthe percentagesame blockage,reduction asto conveyance alsoas conveyance depends on flowthe area,Manning’s hydraulicn radiusvalue, flow area and Manningshydraulic nradius.

For more control over blockage representation, the pBlockage attribute is recommended where available (for example with circular culverts or 2D HX lines). However, for irregular shapes where pBlockage is not supported, using the a Skew provides(in degrees) attribute is the only anavailable alternativemethod.