The US Army Corps of Engineers (USACE) Hydrologic Engineering Center (HEC) is the designated Center of Expertise for the US Army Corps of Engineers in the technical areas of surface and groundwater hydrology, river hydraulics and sediment transport, hydrologic statistics and risk analysis, reservoir system analysis, planning analysis, real-time water control management and a number of other closely associated technical subjects. The HEC supports Corps field offices, headquarters, and laboratories by providing technical methods and guidance, water resources models and associated utilities, training and workshops, accomplishing research and development, and performing technical assistance and special projects. HEC models and techniques are widely used by public agencies and by the private sector. One such model is the Reservoir System Simulation program (ResSim). For further information on the USACE HEC visit their website at http://www.hec.usace.army.mil/.

The NWS operates thirteen River Forecasts Centers (RFCs) that provide flood and water supply forecasts, guidance, and information for the protection of lives and property and the enhancement of the environment and economy. To accomplish this, the RFCs utilize a suite of software applications called the National Weather Service River Forecast System (NWSRFS). The NWSRFS is a collection of hydrologic models, operations, and data processing functions supported within a well-tested and rigorous operational infrastructure. The NWSRFS was developed by the NOAA/NWS Office of Hydrologic Development (OHD).

The Yuba County Water Agency (YCWA) is leading an interagency effort to develop "Forecast-Coordinated Operations (F-CO)" for Lake Oroville on the Feather River and New Bullards Bar Reservoir on the Yuba River in California. Agencies include the California Department of Water Resources (CADWR), the NWS California-Nevada River Forecast Center (CNRFC), the USACE HEC, and the YCWA. Representatives of these collaborating agencies have agreed to use the HEC’s ResSim model as the centerpiece model for a new decision support system. In order to meet the project requirements, ResSim must be made compatible with the CNRFC operations, who in concert with the CADWR, provide hydrologic forecast and warning support for the Feather and Yuba rivers during routine as well as flood emergency conditions.

Using ResSim within the operations of the CNRFC ensures that all project participants have an identical representation of the river system at all times. To accomplish this, ResSim must be effectively integrated within the CNRFC’s operational system, the NWSRFS. Direct coding of ResSim into NWSRFS is not desirable because expected modifications and updates to ResSim could not be effectively integrated. As such, the YCWA requested, and the OHD agreed, that the OHD would develop a portal from NWSRFS to the most recent version of ResSim available from the USACE using a "service-based" architecture. This is entirely compatible with the OHD's strategy for CHPS.

Through the NWS contract with RSIS, the OHD sub-contracted with Apex Digital Systems in 2006 to analyze, design, and develop a solution for the CNRFC that not only meets the requirements of the F-CO, but will also be "CHPS-ready". Since Delft-FEWS is under consideration as an infrastructure solution for CHPS, Apex’s proposed solution centered on a ResSim interface to NWSRFS through the Delft-FEWS. While this makes for a somewhat ‘heavier’ solution with more features than are absolutely necessary for this project, the advantage is that future migration of the CNRFC's ResSim interface to a CHPS environment will be significantly eased.

Having approved this approach, the OHD authorized Apex to begin final implementation for the ResSim project in early April 2007. For updates concerning activities on this project, visit the CHPS News & Activities page.

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