This Manual is not intended to teach you how to do hydrologic engineering or even hydrology. It does not describe the mathematical equations for the various models included in the program. So what does it do? This Manual will teach you how to use the various features and capabilities of the program. It works very well to simply read the Manual through starting at the beginning. If you read the Manual in front of your computer with the program up and running, it will work even better. However, the Manual works equally well as an occasional reference when you cannot remember exactly how to perform a certain task or need to check the parameter definitions for a particular method.
The scope of this Manual does not mean that we think engineering applications or mathematical analysis are unimportant. In fact, both of those things are vital to producing good engineering plans and designs. We feel they are so important that we have created a separate Manual for each of them. The Technical Reference Manual provides detailed descriptions of each of the models included in the program. You can expect to find the mathematical derivation of the model equations, details on the numerical schemes employed in the program to solve the equations, and specific guidance on parameter estimation. Consequently, it focuses less on using the program and more on understanding the science of hydrology. The Applications Guide provides practical suggestions for using the program to perform engineering work. We selected a number of typical projects that engineers often encounter and showed how the program can be used to provide real answers. Consequently, it focuses less on using the program and more on the engineering process.
Many engineers, computer specialists, and student interns have contributed to the success of this project. Each one has made valuable contributions that enhance the overall success of the program. Nevertheless, the completion of this version of the program was overseen by Matt Fleming while Christopher N. Dunn was director of the Hydrologic Engineering Center. Greg Karlovits and Thomas Brauer led the HEC-HMS team during the Version 4.4 release cycle. HEC-HMS team members contributing to the version 4.4.1 release include Mike Bartles, Jay Pak, and David Ho.