TxDOT Research Library - TxDOT Research Project

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New Rainfall Coefficients

What Was the Need?

Depth duration frequency (DDF) and intensity duration frequency (IDF) of annual maximum rainfall throughout Texas needed to be updated from previous research and implementation projects sponsored by TxDOT (Asquith, 1998, and Asquith and Roussel, 2004).

What's the Solution?

Depth-Duration-Frequency coefficients for Texas were updated to 2015 DDF values. The 2015 DDF values were used to estimate the 2015 ebd values to parameterize the intensity equation in the Texas Hydraulic Design Manual. A computational tool named EBDLKUP-2015.xlsx was built to replace an earlier tool in common use in Texas. The tool differs from the earlier tool in appearance, and is password protected to reduce unintentional changes to the underlying database. A companion tool named TXHYETO-2015.xlsx was built to enable designers to rapidly generate Texas specific hyetographs for importing into HEC-HMS and similar hydrologic modeling software using an approximation to the tabulations reported in Williams-Sether and others (2004). Training tutorials, a training video, and a training module are included.

Research Benefits

The new values and software tools enable designers to rapidly generate Texas specific hyetographs for importing into HEC-HMS and similar hydrologic modeling software. The training materials will facilitate rapid deployment of the tools.

The results of this research are fully implementable as-is and will provide the department a functional tool until a NOAA Atlas 14 product is completed for Texas.

Project Number

0-6824

Status

Completed

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