Branch trimming, also referred to as Branch Collapsing, is the process of removing short dead-end links and their corresponding junctions. Since pipes and junctions are removed by this process, you specify the criteria for both types of element. An important element of this skeletonization type is the reallocation of demands that are associated with junctions that are removed. The demand associated with a dead-end junction is assigned to the junction at the beginning of the branch.

Branch trimming is a recursive process; as dead-end pipes and junctions are removed, other junctions and pipes can become the new dead-ends—if they meet the trimming criteria, these elements may also be removed. You specify whether this process continues until all applicable branches have been trimmed or if the process should stop after a specified number of trimming levels.

Branch trimming is an effective skeletonization technique; dead-end junctions with no loading have no effect on the model, and dead end junctions that do have demands are accounted for at the point through which this flow would pass anyway (without skeletonization), so the hydraulic behavior of the network as a whole is unaffected.

A drawback to this type of skeletonization is that information and results cannot be obtained from non-existent elements. During water quality or fire flow analysis, information on these trimmed elements may be desired but unavailable. Having multiple models utilizing various levels of skeletonization is the solution to this potential issue.