A Practical Introduction to 2D River Modelling in HEC-RAS

Open the map environment, select the Muncey Mars project, and load the appropriate .prj projection file to set the terrain projection, unless the terrain model already has one.

Load and create a terrain model in Mars Mapper, import a TIFF terrain file with its projection, convert to geotech, and visualize with contours for river channel refinement.

Import 1d cross-section geometry data into the 2d river model, view geo-referenced sections in the cross section viewer, and save the geometry as muncey geometry for later carving.

Create a 2d river model in HEC-RAS by editing geometry: enable bank lines and cross sections, generate an interpolation surface, and save edits to build a detailed channel network.

Create and merge terrain layers in a 2d river model by exporting the channel geometry as terrain, importing the base dtm, and merging rasters with the channel above the base.

Plot cross sections 1–61 and the Blue River line with bank lines, then overlay terrain data and Google satellite imagery to refine roughness layers for the 2D river model in HEC-RAS.

Create a Manning's n layer from a 10 m land cover tile from the usgs national land cover database and integrate it into the 2d river model.

Assign Manning's n values to land cover types and draw a channel classification polygon in Rouse Mapper by tracing bank lines for 2D river modeling in HEC-RAS.

Create a user defined Manning's layer by building an empty land cover, adding polygons with Manning's values for grassland and willows, and saving the classification for model input.

Create a 2D flow area inside a bend, touching cross-sections via perimeters, with a 50-meter grid, and generate computation points and property tables for the flood plain area.

Learn to edit 2D flow area polygons in HEC-RAS using perimeters and the pencil tool. Move and add vertices, undo/redo changes, and plot terrain beneath the polygon.

Update 2D area meshes in HEC-RAS after boundary edits by generating computation points with bright lines, and inspect hydraulic properties for each cell face via plots to verify accuracy.

Learn to add brake lines in a 2D flow area to align mesh cells with flow around bridges and roads, and adjust near spacing and near repeats.

Refine the 2D mesh with refinement regions, draw a polygon around housing, set a 15 by 15 meter cell size, enforce transitions, and recompute out-of-date matches.

Learn how to create Manning's n calibration regions in HEC-RAS, overlay calibration areas on the land cover, and adjust land-use specific Manning's n values without altering the base land cover.

Open the manage geometry associations tool and link the new terrain Muncie with the land cover layer. Enable the model to combine data from the related layers.

Compute hydraulic property tables for each 2D cell face and plot volume, area, weighted perimeter, Manning's n, and conveyance versus elevation; auto cell generation is powerful but can fail.

Learn to connect a 1D channel to a 2D area with lateral structures in HEC-RAS mapper, placing an interface between cross sections around 47 and 42 with a notional height.

Build the second lateral structure downstream from cross section 27 to 4 in a 2D river model, using the geometry editor to place points and set a two meter width.

Enter and edit two lateral structures in the geometry editor, configure upstream locations, headwater connections, and 2D flow areas, and save geometry data for 2D river modelling in HEC-RAS.

Edit the downstream lateral structure in the geometric data editor, setting headwater overbank, storage area, overflow method, and embankment data with cross-section connections and 2D terrain integration.

Enter unsteady flow data by configuring boundary conditions and loading a Muncey hydrograph, then apply Manning's equation with friction slope of 0.0005 and flow 32 qmax, save as Munsey Flow.

Set up an unsteady flow simulation in HEC-RAS by selecting geometry and flow files, running the geometry preprocessor, configuring cross-section hydraulic tables, and choosing computation and output intervals.

Master unsteady flow modeling in HEC-RAS by configuring computation options and tolerances. Learn to manage time steps, warm up periods, and iteration controls for stable, accurate results.

Explore calculation options 2 in 2d river modeling for hec-ras, detailing flow options, Coriolis effects, diffusion wave vs momentum equations, initial condition ramps, and time slices.

Explore unsteady flow options and computation tolerances for 1D to 2D connections, including water surface, flow, and minimum flow tolerances, plus mixed flow regime and LP-based stability near critical depth.

Perform an unsteady flow analysis for a 2D river model in HEC-RAS, tune the computation interval, and assess volume accounting and results via the post processor.

Explore 1D and 2D river results in the Rouse Mapper, using long profiles, cross sections, and river stationing to track water surface, bed elevations, and lateral structures.

Learn to view 1D results in HEC-RAS, including stage and flow hydrographs, cross-section data, rating curves, and exportable tables for lateral structures, plus warnings and 3D plot options for visualization.

Explore 2D results in Rao's mapper for HEC-RAS, compare dynamic time mapping with stored maps, and adjust depth, velocity, and water surface while examining interpolation and display options.

Explore 2D results in HEC-RAS by plotting depth time series and profiling depth along the channel. Visualize velocity with static arrows and particle tracing, and view water surface elevation.

Explore 2D results in HEC-RAS by using rounds mapper to display depth, switch to Google satellite or terrain, save bespoke views, and query velocity and time-series hydraulic properties.

Adjust the 1D theta weighting in a 2D river model in HEC-RAS, compare plan one and plan two results, and enable the mixed flow regime to account for critical depth.

Modify the 2D flow equations from diffusion wave to shallow water, tune the computation interval to three seconds, and compare Plan one and Plan two results for 2D flow.

Adjust 2D computation options in HEC-RAS by enabling boundary condition volume checks, using shallow water equations, and tuning the computation interval from 30 seconds to 3 seconds for unsteady flow.

Tune the time step in HEC-RAS by balancing delta t, delta x, and velocity for diffusion wave and shallow water equations, using velocity estimates or current outputs.

Adapt time steps in 2D river modelling with HEC-RAS using current numbers to guide adaptive controls, ensuring stable, efficient simulations.

Copy your existing HEC-RAS model into a new 2D project folder. Remove unneeded plans and geometry, leaving the 2D terrain and land cover for the new model.

Create a new 2D flow area that covers the entire land cover polygon using a geometry file and 50 spacing to generate a grid for the channel and floodplain, then save.

Trace the channel in a refinement region within the 2d flow area, edit geometry along the banks, and save edits before defining the cell size in the next lecture.

Set the refinement region cell size to 10 meters and enable one cell protection radius, then enforce all regions and fix a 2D geometry error with try to fix MASH.

Align cells in the refinement region with the channel flow by drawing a centre line, setting near spacing and four cells on each side, then enforce brake lines.

Configure geometry associations for the 2D river model, then draw external boundary condition lines for inflow and outflow using the geometry editor and RAS Mapper.

Discover boundary and initial conditions for 2D river modelling in hEC-rAS, including external, internal, and global options, with flow and stage hydrographs, normal depth, and various initial-condition types.

Edit the boundary condition data for the abc line outflow and inflow using Manning's equation to set the outflow depth and import the monthly flow data into the flow hydrograph.

Learn to set up an unsteady 2D river model in HEC-RAS, configure initial conditions and ramp-up, apply warm-up steps and adaptive time stepping, and evaluate stability.

Explore unsteady flow simulation in a 2d river model and see how adjusting land cover roughness, especially channel and outer bank values, changes the maximum inundation extent in Raaz Mapper.

Switch from diffusion wave to shallow water equations in unsteady 2D river modelling and compare plan one and plan two depth outputs using the RASter calculator.

Compare 1D and 2D modeling and steady versus unsteady flow to decide the appropriate modeling approach; use 2D behind levees and wide floodplains, while 1D suffices for dominant river-path flows.

Explore 2D river model results in 3D using Razz Mapper, fly around the terrain with keyboard, mouse, or a game controller, and simulate along a flight plan.