Hydrologic Analysis using Civil Design versus HEC-HMS on Horsethief Creek Canyon Wash, California
This project develops an effective process to compare hydrologic results from CivilD and HEC-HMS. CivilD is a hydrologic modeling software used in Southern California: specifically Riverside, Los Angeles, San Diego, Orange, and San Bernardino counties. The software has a fee, but contains all of the necessary parameters to model a watershed with respect to the requirements in the jurisdictions with which it has received approval. HEC-HMS is a free hydrologic modeling software provided by the US Army Corps of Engineers, where the engineer needs to input all the necessary parameters. The results show that the percent difference between CivilD and HEC-HMS is 2.08% on average between varying storm return periods and durations. The greatest error occurs during the 25 year 24 hour storm due to, what is believed to be, variation in rounding of excess precipitation values between HECHMS preprocessing and the CivilD software. The study does not recommend the use of either software, it merely illustrates that they are both reliable tools for calculating flow rate. Based on our findings, we are able to verify the results of HEC-HMS with CivilD, and provide users with a clear understanding of the various inputs and outputs the programs require and generate, respectively. In addition, HEC-HMS allows a user to test various other hydrologic modeling methods, as the program provides a platform for more user autonomy. Thus, a user will gain value through exposure to insights this paper provides, which explain why a certain method is applicable for this project.