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South Platte CWMS ModelMissouri Basin Forecasters Meeting

January 29, 2014

South Platte CWMS ModelMissouri Basin Forecasters Meeting

January 29, 2014

Brian Twombly, Omaha District, Corps of Engineers

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Corps Water Management System (CWMS)

Developed by the Hydrologic Engineering Center (HEC). Software that Interfaces:

• Data Acquisition• Data Storage• HEC-HMS (rainfall/runoff)• HEC-ResSim (reservoir routing)• RiverWare (river system)• HEC-RAS (hydraulics)• HEC-FIA (economic consequences)

HEC-RTS is the personal computer version of CWMS that interfaces all the models without the database connections.

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HEC-HMS

Three models were developed:• Upper Basin Snow• Upper Basin Rain• Middle Basin Rain

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Upper South Platte- Two different basins: Rain and Snow- Gridded snow and air temp from CRREL and NOHRSC

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Mid South Platte- Requires an input at the Waterton gage either from the upper HMS or NWS forecast.

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HEC-ResSim

HMS inflows fed into ResSim ResSim computes reservoir releases for:

►Chatfield►Cherry Creek►Bear Creek

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HEC-RAS

Uses outflow from ResSim in reaches downstream of the reservoirs.

HMS provides flows to other reaches.

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Model Development - GeoRAS

DEM:•2 meter LiDAR data for core Denver Metropolitan area, obtained in 2008. •10 meter DEM outside LiDAR extents, provided by the district.

Centerline Development:•Digitized from aerial imagery for South Platte River and the major contributing tributaries in the basin.•Centerlines in Green.

Cross Section Geometry :•Cross sections in Red.•Developed by RAS team.•Storage Areas in Blue.

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HEC-FIA

Calculates flood damages and loss of life Uses inundations calculated in HEC-RAS

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Data Needs

Forecasted Temperature Grids►CRREL to provide grids from NOHRSC►3 days forecasted temperature►Any other sources of grids?

Historical gridded temperature and precipitation►Could be used to develop spaghetti plots and

probabilistic forecasts.

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Data Needs

NWS Waterton Forecast►6 hour time step►Could be used instead of running the upper

HMS model. How are the radar precipitation grids

ground truthed?

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Questions

Brian Twombly, P.E.

brian.j.twombly@usace.army.mil

(402)995-2316

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South Platte ResSimSimulations

Sept 2013 Flood Simulation

Transposed rainfall grid for 10-16 Sept 2013

Created new rainfall grid over reservoir watersheds

Developed hydrographs using 75% HMS models

Create a Sept 2013 ResSim simulation using HMS results

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South Platte ResSimSept 2013 Simulation

Transposed Rainfall Grid

HEC-MetVue, Gage Interp, ArcGis

Created a grid of circles with Excel and ArcGis

Transposed gridded rainfall with MetVue

Re-sampled gridded rainfall by average rainfall for each circle over the time period of the gridded rainfall dss file

Created a new gridded rainfall file with Gage Interp

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South Platte ResSimSept 2013 Simulation

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Sept 2013 SimulationCherry Creek Basin Storm Centering

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Sept 2013 SimulationDownstream Storm Centering