Triangular Shape
In general, it can be said that the triangular version will not cause or introduce noticeable differences in the simulation of a storm event, particularly when one is concerned with the peak flow.
For long term simulations, the triangular unit hydrograph does have a potential impact, due to the shape of the recession limb.
The U.S. Army Corps of Engineers (HEC 1990) fits a Clark unit hydrograph to match the peak flows estimated by the Snyder unit hydrograph procedure.
It is also possible to fit a synthetic or mathematical function to the peak flow and timing parameters of the desired unit hydrograph.
Aron and White (1982) fitted a gamma probability distribution using peak flow and time to peak data.