Flooding Risk Assessment with Hec-Ras, Hec-HMS, QGIS

Learn how to download and install open source tools for flooding risk assessment, including QGIS, HEC-HMS, and HEC-RAS, and verify proper setup on Windows.

Learn to prepare data in QGIS by installing plugins, adding Google satellite imagery, downloading Landsat data, selecting study areas with polygons, and configuring UTM projection and export extents for analysis.

Learn to download a spatial reference from spatial reference.org, set up a new cross project in international metric units, and apply a prj projection file for Nova Scotia's coordinate system.

Learn to create a Ras terrain in Grass, clone and resample terrain data, set the coordinate system, and prepare Tehran and Halifax datasets for downstream flooding analysis.

Create a new Hec-HMS project, set up terrain data and a coordinate system, then build and process drainage, identify streams, and delineate brick lines for focused flood analysis.

Learn perimeter delineation in HEC-RAS by creating a new geometry and boundary, then generate a mesh of a chosen size while noting that outside the perimeter does not affect results.

Refining region focuses calculations on a targeted area by creating smaller 10 by 10 meter meshes within a 50 by 50 grid, recalculating results to compare refined versus broader regions.

Understand how land use and land cover drive flood modeling. Download 2020 land cover data from if map catalog, classify land, and prepare it in QGIS for HEC-RAS and HEC-HMS.

Learn to calibrate classifications in QGIS by defining and adjusting roughness coefficient values, create new classes, and override defaults to support accurate flood risk assessment.

Analyze Manning's n as the roughness coefficient that dictates resistance to flow in channels and flood plains, and its impact on velocity and flood modeling.

Prepare precipitation data and boundary conditions, convert units, and configure a rain-driven flood simulation in Hec-Ras, Hec-HMS, and QGIS, then run and review the study flow results.

Analyze flood simulation results by exploring rainfall-driven water flow, velocity, and volume accumulation with profile lines and cross-sections to identify impacted areas.

Troubleshoot flood simulations by examining the Courant number, log files, and runtime messages. Adjust time steps and cell size to keep the Courant number within acceptable limits and improve accuracy.

Learn to configure boundary condition lines and outflow in a 12-hour precipitation-driven flood simulation, define rainfall inputs and slope, and run the updated grid analysis in HEC-RAS.

Analyze simulation results, assess instability indicators, and adjust computing time; explore water levels, flow, and volume evolution using particle tracing, profile lines, and volume accumulation tools.

Create a new geometry to focus a flood study on an area, setting a perimeter and refining regions with 50 by 50 and 10 by 10 cells for hydrograph study.

Modify terrain geometry to form and refine a river channel, adjust cross sections and bathymetry, then save and export updated geometry for flood risk assessment.

Master flow hydrograph analysis by building and simulating flood scenarios in geometry, inflow and outflow boundaries, and boundary conditions, then visualize velocity and flood extent.

Learn to build a dam and bypass channel using terrain modification tools, place houses, and evaluate flood risk with elevation changes and particle tracing in simulations.

Visualize the flood simulation results to compare house elevations and their flooding outcomes, assess dam and bypass performance, and view the 3D results showing high-velocity areas.

Take a three-dimensional visualization of flood results in Tehran, revealing elevation, how water propagates, a dam blocking the flow, and rebuilt houses along the channel.

Explore tsunami hazard and coastal big-wave modelling with Hec-Ras by building coastal geometries, delineating the study area, running a tsunami simulation, and visualizing results in 3-d.