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coordination with participating entities will also ensure that resources are <br />directed in the most efficient manner. <br />4) Hydrologic Model Development — Phase II will consist of hydrologic modeling <br />for approximately 10 additional local watersheds compared to the two local <br />watersheds modeled in the Phasel hydrology. Hydrologic models for the local <br />watersheds will be developed using Geo -HMS to develop detailed geo- <br />referenced HEC -HMS models. This will allow inclusion of existing city and <br />county GIS data, and potentially reduce the time and effort needed to develop <br />hydrologic parameters. The models will include both existing and estimated <br />future land use conditions, and will utilize existing city and county GIS data, <br />regional planning data, and use STATSGO or SSURGO soil information to <br />generate hydrologic parameters. Modified Puls routing will be developed for <br />all detailed study streams. <br />Rainfall intensity and storm frequency are important elements in the analysis. <br />Coordination with the USGS and the National Weather Service may aid in <br />developing the most appropriate and accurate rainfall. A calibration analysis <br />based on historical record of rainfall and discharge will be performed. These <br />frequencies will be compared to current USGS regression equations and the <br />current FIS flow rates where available. <br />Detailed hydrologic models using uniform rainfall will be developed for <br />tributaries identified by participants. These models will be developed using <br />methods appropriate for the study areas. <br />The USACE, GBRA, and their contractors will perform all development of <br />HMS models described above. <br />5) Hydraulic Model Development — Collected field survey data, information from <br />design plans, recent topographic data, and the existing conditions hydraulic <br />models will be updated and converted to HEC -RAS format. The HEC -RAS <br />models will be geo- referenced to correlate with city and county GIS data, <br />using the HEC- GeoRAS extension in ArcMap 10. Roughness coefficients <br />(Manning's N) will be developed utilizing GIS overlays and supplemental field <br />observations as well as calibration to storm events. Flood profiles for multiple <br />frequency storm events will be developed for the existing and future <br />watershed conditions. A detailed report that summarizes the modeling results <br />will be prepared. Reports will include presentation of the methods of analysis, <br />summary of results, exhibits, and model output. Surveys will be more <br />detailed through damage centers with less detail for the stream reaches <br />between damage centers. <br />6) Evaluation of Flood Protection Criteria — The USACE, GBRA, and their <br />contractors will review existing design flood criteria for the problem areas and <br />acceptable levels of protection within each problem area will be determined. <br />7) Hydrologic and Hydraulic Analysis of Alternatives — The USACE, GBRA, and <br />their contractors will proceed with development alternatives, which may <br />include alternatives or combinations thereof developed in the previous study <br />