Using Streamgage Data – StreamStats to Bulletin 17C Frequency Analysis

Date / Time: February 20, 2019 2:00 pm

Participants will learn about how to determine the likelihood of flooding at any given site in a stream corridor, using two recently updated analysis tools: the USGS web-based tool StreamStats, and computer programs to compute streamflow frequency of gage. Efforts to design and build beneficial projects in stream corridors require an analysis of the frequency of streamflow flooding. Flows ranging from very low to very high are associated with a statistical likelihood of occurrence. Projects are designed to withstand flooding to a pre-determined flood recurrence level, often dictated by local or state ordinances. Engineers must use up to date and defensible analyses to determine these critical project parameters. The size and cost of stream corridor projects is directly dependent on these determinations. StreamStats is a statistical regression based method. The computer programs PeakFQ and HEC-DSS use annual peak flow data from stream gages to create streamflow frequency curves.