Detailed Hydraulic (Flood) Modelling

Detailed Hydraulic (Flood) Modelling

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Detailed flood modelling to understand flood risk in virtually any environment throughout the UK

Our experienced flood consultants can create 1D and 2D hydraulic flood models to supplement your Flood Risk Assessment, assessing the impact of flooding on a development, and the impact of a development on the surrounding area. This is especially helpful if your development site is lacking in up-to-date EA modelling data or has a particularly complex hydrological environment.

Often, the Environment Agency (EA) has modelled data that is available for use to create a sufficient Flood Risk Assessment in order to pass planning. However, this is not always the case. In fact, there are many areas of the UK that hasn't been modelled by the EA in a recent years, or at all. This is where Hydraulic (Flood) Modelling comes in.

Dynamic hydraulic modelling can simulate rainfall, river, and tidal water sources in complex environments.

  • Accurately model the flood levels on your site, including climate change allowances
  • Support your planning application
  • Make more informed decisions
  • Understand flow and water levels in rivers, estuaries, and coastlines
  • Understand the flood extent, depth, velocity, hazard, timing, duration, and flow paths for fluvial or tidal flood plains
  • Understand loadings on flood defences

What is 1D and 2D flood modelling and how can it support my project?

1D and 2D hydraulic models are used to assess the full impact of flooding on a development, as well as the development's impact on a local watercourse. They can be used separately, or together in a combined 1D/2D model, depending on the complexity of the site and what information is needed.

This allows us to create accurate flood maps to support your planning applications and develop effective mitigation options, keeping your site and its occupants safe.

Our experienced flood modellers and consultant team are trained to use the latest software, tailoring our models and reports to your requirements, in line with budget, timescales, and data needs.


How our consultants can help your project

Our flood modelling team has significant experience of delivering site specific and strategic flood models, enabling the development of a streamlined methodology. This methodology has been shaped through conversations with the flood modelling and forecasting team at the Environment Agency, meetings and site inspections with Lead Local Flood Authorities, and meetings with third party technical reviewers.

We use the feedback from the stakeholders and our clients to continually improve our flood modelling service.  This is exemplified through our use of a powerful and dedicated flood modelling machine, which has been built to enable our team to deliver not just the base results but a sufficient range of sensitivity testing simulations to be enable a deeper understanding of the flood mechanism at the site and in the surrounding area.

What this means is that from the outset we will be able to adapt our methodology and processes to define a suitable area of interest and to deliver a flood model that is appropriate to the scale of the development.

Get in contact with us today on +44 (0) 1273 006 900 or request a free quote and one of our friendly specialists will be in touch

What modelling approach is most suitable for my development?

When to use 1D modelling on a project

A 1D flood model represents the river network by connecting cross-sections taken through the river and the land and simulating the water level as it flows through the model.

The flow is only in 1 Direction (hence the 1D abbreviation) along the river channel, the flow can go backwards, for instance where a structure is present that restricts the passage of water. There are a number of weaknesses to this approach, the main one being it is assumes that the floodplain between the cross-sections is the same.

Obviously this is often untrue especially in urban areas were the networks of roads and spacing of buildings can alter the flow.  Where railway lines are present in cuttings these can effectively act as channels, however more normally railways are embanked forming a barrier to flow.

Traditionally the 1D models were used for flood forecasting of live events, because they run more quickly than 2D models. 1D model elements also include below ground pipes and drainage that can be used.

1D Flood Modelling Animation
1D flood modelling long-section showing the build up of flood water upstream of a culvert

1D Flood Modelling Schematic
1D flood modelling schematic image

2D Flood Modelling Schematic
2D flood modelling schematic image

When to use 2D modelling on a project

A 2D model (often linked to a 1D model of the channel between the river banks) uses a grid across the floodplain area to represent the changes in the ground between cross-sections.

This grid samples the ground levels from a variety of survey sources, so that the model considers the variation of the ground terrain within the model.  Please note that flood modelling convention removes building footprints from the floodplains and is based on a bare earth terrain model.

This grid allows 2D models to simulate the flow forwards and backwards like in a 1D model, but also allows water to flow left and right across this means that were flow would travel away from a river it can then flow back into the river at some point further downstream.  This gives a better representation of the flow regime, whereas in a 1D model such out of bank flow routes would need to be manually defined, and often local flow routes were not represented in the large scale strategic models.

Our dedicated flood modelling computer can run 2D models faster than traditional 1D models, the computer can run simulations 15x faster than the previous technology allowed.

In most circumstances we would recommend the use of a 1D/2D linked model for the UK, with the river channel represented in 1D and the out of bank flows represented in the 2D model. For larger channels a 2D only model can be suitable, given the wide braided nature of these channel types

Most flood models produced aim to answer the question: is the site at risk of flooding? If it’s proven to be at risk, the next question is: how can I shape my development to be compatible with the flood risk? A sufficiently detailed flood model can answer these questions, it can also answer the following:

  • Will I be allowed to build a flood wall or bund around my property/asset? – Use Flood Defence Impact Modelling
  • I’m looking to build near a watercourse or in an area of surface water flood risk, how can I make it safe? – Use Development Flood Modelling
  • We are a community at risk of flooding and we are looking at property level protection (PLP), what are the flood levels for each property? – Use Flood Resilience Modelling
  • We are looking to improve the drainage network in an area, based on its current condition which properties are at greatest risk of flooding? – Use Flood Resilience Modelling
  • The Environment Agency / Local Council are objecting to my Planning Application, but are unable to provide modelled flood levels, to set my finished floor levels too, what is the flood level at the site? – Use Development Flood Modelling
  • I’m responsible for a sensitive infrastructure asset, and I need to understand the potential worst case impacts of climate change, to inform my emergency response plan, what routes will be safe to and from the site in the event of a flood? – Use Flood Resilience Modelling
  • I have a large above ground storage tank (holding a liquid) if this fails where on my / or my neighbours land, would be at risk. Also are my bunds high enough? – Use Onshore Spill Modelling.
  • We are looking to reforest a portion of our land, what benefits to flooding could this have? – Use Natural Flood Management Modelling
  • We are looking to improve the network of ditches and watercourses within out land, what benefits could this have to others? – Use Natural Flood Management Modelling

Get in contact with us today on +44 (0) 1273 006 900 or request a free quote and one of our friendly specialists will be in touch

Modelling Tools We Use

Our modelling experts use a range of industry leading tools to accurately model flood data on your site. This includes our own independent flood modelling software (Flowroute-I™). This allows us to provide the most accurate representation of flood risk for any site throughout the UK, so you can effectively mitigate against any potential flood event.

Planning Applications


Flowroute-i™ is Ambiental's in-house flood modelling software. The suite of programs is highly compatible with all common GIS platforms and is highly adaptable. This allows us to create highly bespoke models for many scenarios and iterations as required more rapidly than other modellers, saving a considerable amount of time and cost for our clients.

Learn More About Flowroute-i™

TuFlow Logo


TUFLOW Products are a suite of advanced numerical engines and supporting tools that simulate free-surface water flow for urban waterways, rivers, floodplains, estuaries, and coastlines. We use TUFLOW to model both 1D and 2D flood flows.

Flood Modeller Logo

Flood Modeller

Flood Modeller's 1D and 2D solvers allow seamless modelling of rivers, floodplains, and urban drainage systems. It's flexible and allows a good level of detail to understand the challenges of the site's flood risk, allowing for easier mitigation.

Microdrainage Logo


MicroDrainage is an advanced drainage design software that focuses on performance and effectiveness of drainage sustems. We use this to  support our SuDS designs to ensure our drainage designs are sustainable and effective for the predicted level of flooding.

Hec-Ras Logo


The Hydrologic Engineering Center's (CEIWR-HEC) River Analysis System allows us to perform 1D steady flow, and 1 and 2D unsteady flow calculations.

Steven Brown Ambiental Associate

Get In Touch With Our Flood Modelling Team

To get a quote or to discuss what you need, contact one of our Modelling Consultants.

Call the team on +44 (0) 1273 006 900  or email at [email protected]

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