The Strategic Alliance for Risk Reduction II (STARR II) is a joint venture focused on flood risk mapping, assessment, communication, and mitigation. Under the mission to reduce the loss of life and property caused by floods, STARR II assists the Federal Emergency Management Agency (FEMA) in working with communities across the nation to prepare for and respond to these natural disasters.
In September 2020, Trihydro was selected as a subcontractor to provide hydraulic analysis and flood mapping deliverables. Trihydro used the US Army Corps of Engineers (USACE) River Analysis System (HEC-RAS) software to model 52 river miles covering 12 streams in two counties (Carbon and Monroe) in northeastern Pennsylvania. The hydraulic modeling incorporated detailed field survey information for over 80 structures and used high-resolution spatial datasets to parameterize the models. Trihydro also used lidar-based digital elevation model (DEM) datasets and bathymetric survey information to create the hydraulic model cross sections.
Modeling included the Standard Identification Number (SID) 84-compliant modeling events (10%, 4%, 2%, 1%, 0.2%, and 1%-plus), as well as a floodway analysis. Results were used to create flood map products for inclusion in updates to the countywide Flood Insurance Study (FIS) reports. As part of this effort, Trihydro prepared floodway data tables for the study streams and a Hydraulic Analysis Report documenting the methodology, assumptions, and data used in the hydraulics analysis. Additionally, Trihydro developed a GIS database compliant with the “Hydraulics Data Capture Standards, Technical Reference: Data Capture Standards (February 2019).”
Trihydro’s work with the STARR II team in support of FEMA will help communities to make better-informed flood and risk management decisions.