Integrated 1D/2D Flood Model



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A Realistic View of How Overland Flow Interacts with Existing Systems.

xp2D, a 2-dimensional overland flow module for xpswmm and xpstorm, gives you the power to analyse and predict potential flood extents, depth and velocity and accurately models the interaction of surface and underground systems in an integrated 1D/2D modelling environment. The software can also be effectively used to simulate and analyse tidal surges, dam breaks and breaches on sewer networks.

xp2D simulates the complex hydrodynamics of floods and tides by combining the full 1D St. Venant equations and the full 2D free-surface shallow water equations.


Combine dynamic 2D overland flow calculations with 1D network analysis for a powerful result:

  • Analyse the whole drainage area in a single model: hydrology, channel flow, pipe flow and overland flow
  • Create accurate flood maps with confidence using fewer assumptions
  • Model structural failures (dams, levees, floodwalls) to allow detailed analysis of emergency response scenarios
  • Identify trouble spots in a 1D network by simulating surface flooding, its flow path and recession after a storm

WHY xp2D?

Accuracy. When it comes to flooding, accurate simulation and forecasting can save lives and property. A simulation model that can demonstrate how water moves over land and how it interacts with its terrain as well as the existing system helps you minimise risk, protect lives, homes, businesses and public dollars.

Rigorously Tested and Approved. xp2D has been benchmark tested by the U.K. Environment Agency and is approved by the U.S. EPA for FEMA National Flood Insurance Program submission.

1D/2D Integration. The combination of the 1D network flow with 2D surface flow uses the best description of the flow for each case — no need to use inadequate approximations. See how flood waters on the surface interact with an existing river or pipe system. Watch as storm sewers surcharge, waters flow down streets or across land surfaces and either pool or re-enter the system. Complex situations such as flood plains with braided river systems can easily be analysed with xp2D.

Structures and Terrain. Model not only the land terrain but its specific attributes. Factors in a model can include different types of land use, buildings, structures, dams, levees, fences and more.

Powerful Analysis. Using the powerful and well-accepted TUFLOW analysis engine coupled with the versatile xpswmm or xpstorm 1D engine, xp2D solves the full 2D shallow-water equations on a finite-difference grid. This means that you will get accurate hydraulics answers, stable model runs, and relatively fast run times — key requirements that must be balanced in a model suited for real-world use.

Presentation of Results. All of xpswmm and xpstorm’s familiar tools for generating tables, graphs, and animations are available for reviewing, analysing and presenting model results. New 2D and 3D animation tools make it easy to present results to managers, decision makers, and even public audiences.


Use xp2D to model complex hydrologic and hydraulic features such as:

  • Urban floodplain areas with dual drainage systems or combinations of enclosed drainage systems, open channels and overland flow paths
  • Braided river systems with significant overbank areas
  • Tidal surges, dam breaks and levee breaches and their impact on 1D systems
  • "Flat" areas where flooding may be caused by heavy rainfall and its recession over time
  • Impact of flooding on non-connected 1D systems such as parallel rivers, drainage canals and irrigation systems


  • Broad surface drainage such as parking lots, commercial sites, golf courses, etc.
  • Flood Hazard Mapping including extends of flooding (depth and velocity), emergency response procedures and design engineering solutions to mitigate impact of flooding.
  • Flows or overbank spills conveyed over flat terrain where the flow paths vary


Emergency Planning | XP2D Manual | Brochure | Request Demo/Info

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