Applies To
	Product(s):	PondPack, Civilstorm, SewerGEMS
	Version(s):	V8i, CONNECT Edition
	Area:	Dataset
	Original Author:	Kathy Wiggins, Bentley Technical Support Group

Problem

Where does the data for the 'BUL70-71' and 'BAS70-71' Dimensionless Rainfall Curves come from? And what is the difference between the two?

Solution

The data for the rainfall curves comes from the Illinois state water survey bulletin 70 and 71. These are sometimes referred to as Huff Distributions and are dimensionless time, so you can apply both a duration and a depth (in contrast to the SCS types which are not dimensionless time and are locked to 24 hours).

The 'BAS' contains data that comes directly from this bulletin. The 'BUL' is derived from the same bulletin, BUT has more times steps (and is thus more precise). The 'BUL' includes interpolated values from Bentley, which are provided for better computer modeling purposes. It is best to use the more precise data set when modeling with our program.

See Also

Stormwater Conveyance Modeling and Design (book - starting page 98)

Modifying and adding entries to Engineering Libraries

How can I apply a rainfall depth or intensity to a dimensionless curve to create a storm event?

Dimensionless Huff 10-50 2ndQ 50% and 50-400 3rdQ 50% distributions throw an index was outside the bounds of the array error