Urban Flood Model

Integrated simulation of rivers, sewers, and floodplains for urban flooding

The Urban Flood Model brings the "Urban Flood Prediction Analysis System (Ver.1.5)", co-developed by Prof. Makoto Takeda (Chubu University) and Kajima Corporation, into the iRIC environment. It couples 1D unsteady river flow, 1D sewer networks (manholes, conduits, pumps, storage tanks), and 2D floodplain flow to simulate river flooding, inland flooding, and sewer overflow in a single framework.

Key Features

Sewer grid input

Model underground sewer networks and use them together with river analysis.

Configurable items

Manhole data

Setting item
X coordinate
Y coordinate
Manhole ID
Manhole invert elevation
Manhole section type
Internal width / diameter
Internal length / diameter

Conduit data

Setting item
Conduit ID
Downstream manhole ID
Upstream manhole ID
Internal width / diameter
Internal height / diameter
Downstream invert elevation
Upstream invert elevation
Conduit section type

Sewer grid input — Sewer grid display (manhole invert elevation MZO)

River connection boundary conditions

By defining how sewers connect to rivers, you can represent drainage, backflow, and other water exchange. Specify the connection location and register it as a boundary condition.

Example river connection settings (type: Connection to river)

Mapping levees, embankments, channel elevation & width

Reflect levees, embankments, channels, and other floodplain geometry in the model.

Visualization of results

Review results on maps and graphs to see where inundation and overflow occur.

Main outputs to review

You can review manhole and conduit water levels and overflow, the spread of surface inundation, water exchange with rivers, and maximum inundation and water levels over the simulation.

Visualization of results — Integrated analysis: inundation (left), sewer water levels (top right), conduit status (bottom right)

What the sewer model can represent

Quantify urban water movement that river-only solvers cannot capture alone.

Flow and storage in pipe networks

Hydraulics of manholes, conduits, pumps, and detention—free surface and pressurized conditions

Manhole surcharge (inland flooding)

Overflow to the surface when capacity is exceeded and its propagation over the floodplain

Exchange with rivers and channels

Outfalls, reverse flow at high river stages, and pump discharge effects

Scenario comparison for improvements

Compare impacts on inundation and overflow across scenarios with pipe size or invert elevation changes

Temporal and spatial outputs

Time series and maps of depth, discharge, and water levels (CGNS visualization, etc.)

Development background (iRIC-UC research group)

Led by iRIC-UC with Chubu University, Kajima, Mizuho R&T, Kozo Keikaku Engineering Institute, and other partners since 2024. Phase 1 (Jun–Sep 2024) achieved an end-to-end workflow on sample data for the Arakawa and Sumida river areas.

Phase 2 (2025–) extends applicability beyond sample rivers, InfoWorks integration, and automated generation of levee and building attributes. Use is limited to participating member companies. Contact us for demos and online briefings.

Join the research group / request a demo

Available to participating member companies. We offer briefings and demos for members exploring sewer-related services.

Usage rights are granted to participating iRIC-UC member companies that meet fee and work obligations.

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