Flood Analysis Model
Independent External Peer Review

An independent external peer review was funded with Federal Emergency Management Agency's Risk Assessment, Mapping, and Planning Partners (RAMPP) studies program to evaluate the technical information, assumptions and methodologies used by the USGS, USACE and NWS to develop the Flood Analysis Model. Dr. Henry Hu of West Consultants, a contractor for FEMA, was hired to perform the technical review. Both USGS and USACE-HEC were given the opportunity to respond to the comments. Their responses are included in the report.

Peer review was conducted to determine the following:

  • the adequacy of the Flood Analysis Model to reproduce observed conditions for the three flood events;
  • the utility of the model to assess the impact of voids in designated Delaware River Basin reservoirs on the downstream river stages for the three flood events; and
  • the utility of the PRMS component of the model to evaluate the impact of watershed conditions on the three flood events.

The reviewer was tasked with reviewing the inputs, methodologies, and supporting documentation for the applications of PRMS and HEC-ResSim. DRBC also requested that the reviewer focus on the following:

  • use of MPE radar data in PRMS;
  • the snowmelt routine incorporated into PRMS;
  • the calibration techniques used for PRMS;
  • how flood control operations are simulated during floods in HEC-ResSim;
  • the routing methods used in HEC-ResSim; and
  • the development of alternate inflow files (FC-GageQ) for HEC-ResSim.

DRBC concurs with the opinions expressed by the peer reviewer, who concluded that the HEC-ResSim component of the model with the FC-GageQ alternative is adequate for the use to investigate the impacts of reservoir operation on downstream river stages for the three flood events. Upon review of initial model calibration, DRBC staff concluded that the PRMS model did not meet the objectives of the Flood Analysis Model project and requested that the FC-GageQ alternative be developed. However, DRBC believes that the PRMS component will be a valuable tool, with additional calibration and along with other models, to perform analyses of water resource management scenarios related to watershed issues. Although the PRMS component of the model the basin runoff fell short of realizing our expectations for the flood analysis model, it holds great promise as one of a suite of models for long term water management for resiliency and sustainability issues. DRBC believes that with the USGS and other partners, it is likely that the PRMS model can be re-calibrated for other purposes with accuracy appropriate for the scenarios being evaluated.