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Guad2D: A Two-Dimensional Flow Model for Floodplain Mapping Over Time

American Water Resources AssociationGIS & Water Resources V

San Mateo, CaliforniaMarch 17-19, 2008

Francisco Olivera, Ph.D., P.E.Texas A&M University

Martin RodriguezInclam S.A., Madrid, Spain

Javier Murillo, Ph.D.University of Zaragoza, Spain

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Ranillas Meander at Zaragoza

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Guad2D

Guad2D is a distributed two-dimensional (shallow-

water) unsteady flow model.

Guad2D models the motion of water over non-uniform

terrain and calculates the water depth and flow velocity

at each point and computational time step, as well as

the evolution the floodplain boundary over time.

Guad2D runs in personal computers with Windows

operating system.

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RESULTS TERRAINROUGHNESSINITIAL CONDITIONSBOUNDARY CONDITIONS

Simulation PeriodStart timeEnd time

GUAD Creator GUAD ViewCALCULATION MODULE

Guad2D Components

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GuadCreator facilitates the input of data: (1) Terrain: Elevation grid or contour lines; (2) Roughness: Manning’s coefficient grid; (3) Boundary conditions: Inlets (i.e., Q(t), h(t)) and control sections (i.e., Q(h)); (4) Initial conditions: Water level before the simulation begins; and (5) Simulation period: Starting time, ending time and output dump interval.

GuadCreator generates the Guad2D configuration files.

GuadCreator uses standard GIS file formats, such as ***, and includes terrain functions such as ***.

GuadCreator

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Guad2D is the flow calculation module.

Guad2D performs calculations fast and is very stable (i.e., no convergence problems.)

Guad2D

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Guad2D averages the Navier-Stokes equations over depth to obtain 2D mass- and momentum-conservation equations.

where h is the water surface elevation, u the velocity in the x-direction and v the velocity in the y-direction.

University of Zaragoza

Fluid Mechanics Area

2 2

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x fx

y fy

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Guad2D

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University of Zaragoza

Fluid Mechanics Area

Guad2D uses an upwind finite volume method and Roe’s approximate Riemann solver.

Guad2D can handle:• Complex geometry and boundary conditions• Fast changes in flow dynamics• Steady and unsteady flow• Wet/dry interfaces.

Guad2D

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GuadView is a GIS itself with specific tools for visualizing Guad2D results.

GuadView can export results to standard GIS formats allowing the overlay with digital orthophotos and other vector and raster layers.

GuadView can display water surface elevations, water depths and flow velocities at each point of the analysis area.

GuadView can create plan-view and cross-section videos.

GuadView can display hydrographs at any user-defined cross section.

GuadView

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GuadView

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GuadView

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GuadView

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University of Zaragoza

Fluid Mechanics Area

Toce River - Validation Case

Toce River in Piedmont, Northern Italy

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Guad2D results were compared to estimates obtained with a scale model of a 5-km reach of the Toce River in Italy.

A number of probes registered the water depth over time.

INLETOUTLET ZONE

RIVER BED RESERVOIR

University of Zaragoza

Fluid Mechanics Area

Toce River - Validation Case

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Inflow hydrograph.

University of Zaragoza

Fluid Mechanics Area

Toce River - Validation Case

An inflow hydrograph was applied upstream. The valley was assumed to be initially dry.

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University of Zaragoza

Fluid Mechanics Area

Toce River - Validation Case

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A comparison between a reduced-scale model developed by the Spanish Centre for Studies and Experimentation of Public Works (CEDEX) and Guad2D was conducted.

In this comparison, the terrain in Guad2D was the same as in the CEDEX’s physical model.

Jucar River - Validation Case

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Júcar River - Validation Case

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The Ranillas Meander is located on the Ebro River northwest of downtown Zaragoza in Spain.

Ebro River - Ranillas Meander

Expo2008

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The Expo Zaragoza 2008 facilities are being built inside the Ranillas Meander.

Ebro River - Ranillas Meander

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The Expo Zaragoza 2008 facilities are being built inside the Ranillas Meander.

A number of flood-protection works have been included to safeguard the new buildings.

Ebro River - Ranillas Meander

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THE END

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Questions?