Updated Rainfall Coefficients for Texas - The EBDLKUP-NEW.XLS Tool

摘要

EBDLKUP.xls is a spreadsheet tool in current use by the Texas Department of Transportation (TxDOT) engineers and other design engineers for estimating intensity-duration-frequency (IDF) of design rainfall by county; the tool differs from discrete-duration IDF in that it facilitates estimation for real-value durations (not discrete durations). This real-value duration capability is a great utility tool for many hydrologic methods such as the rational method. The rainfall coefficients (E, B, and D) for the spreadsheet were created by interpreting the rainfall depth contours by duration and frequencies from research by the National Weather Service completed in the early 1960s and augmented in the 1970s. (TP-40 Hershfield, 1961; NWS Hydro-35, 1977) Recent research projects sponsored by TxDOT have produced newer knowledge related to rainfall depths from longer rainfall records, newer statistical methods, and improved presentation methods. The results of these studies are incorporated into a new tool EBDLKUP-NEW.xls. The new tool was designed to maintain a similar interface and data structure to ensure that the revised coefficients can be inserted into existing design software (GeoPack-Drainage, WinStorm, and other drainage design tools that directly use the E, B, and D values). Added features include embedded depth-duration-frequency (DDF) estimates for use with a companion tool to parameterize empirical Texas hyetographs, embedded documentation, and embedded video training. This paper presents the new tool, the underlying database analysis, and the embedded training concept.