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<br />13. Local Drain 6 <br />14. Rush River <br />15. Drain 30 <br />16. Drain 29 <br />17. Drain 13 <br />II. Calibrate model to match each subbasin’s adopted discharge-frequency to obtain HMS <br />hydrographs for each inlet to the Diversion. <br />III. Obtain the following parameters: Clark’s Tc, R, R/(Tc+R), CN, slopes, and drainage area. <br />Parameters to be used to estimate Diversion inlet discharge-frequency using the NRCS <br />method for small subbasins, as per the ND Hydrology Guide. <br />Deliverables: <br />I. HMS hydrographs at each inlet to the Diversion in a separate DSSVue file. <br />II. List of parameters used or determined such as: precipitation, Clark’s Tc, R, R/(Tc+R), CN, <br />slopes, and drainage area. <br />III. Schematic showing drainage area for each inlet, with the Diversion alignment. <br />IV. Brief report describing method, assumptions, parameters used, maps, and results. <br />B. UPDATES TO THE RUSH/LOWER RUSH: <br />The objective of this subtask is to produce working HEC-RAS models using updated HEC-HMS <br />hydrology for local peak flows in the Rush and Lower Rush areas for use in project design. <br />Scope: <br />I. Red River Peak Flood - Modified Rush River hydrographs from the existing conditions <br />model will be input into the Phase 6 LPP model, which initially will be conducted for the <br />100-year flood event. <br />II. Rush River and Red River Peak Flood - The updated hydrographs from the HEC-HMS <br />models developed for existing conditions will be run for the Red River Peak 10 and 100- <br />year flood events in the Phase 6 LPP model. <br />III. RAS Mapper will be used to map the floodplain outside of the diversion channel for the <br />peak tributary event on the Rush and Lower Rush Rivers. <br />Deliverables: Updated existing conditions and with-project HEC-RAS unsteady models. <br />C. EVALUATION OF CHANNEL SIZE: <br />The objective of this subtask is to evaluate various Diversion Channel width sizes to determine <br />hydraulic impacts based on channel size. <br />Scope for Diversion Channel from the Outlet to the Maple River: <br />I. Evaluate alternatives using the criteria below to assess the size of the Diversion Channel <br />and conduct a Screening Analysis using the HEC-RAS steady state software with the <br />objective of determining the most favorable alternatives: <br />1. Bottom width of the main Diversion Channel. <br />2. Channel bottom elevation of the Diversion Channel. <br />3. Considerations of the water surface profile in the Diversion Channel with <br />respect to existing ground elevations. <br />4. Modification of the Hydraulic Structure at the Maple River. <br />HMG_TO9-A13_Long.docx 2 <br />DR <br />A <br />F <br />T <br /> <br />3/6 <br />/ <br />2 <br />0 <br />1 <br />5 <br />