By: CH2M Global Technology Leader Jon Wicks

Advancements in Flood Modelling

Over the last few decades, software and data used for flood modelling has advanced significantly. Ten years ago, 1D modelling was the standard approach for fluvial flood inundation modelling, and the availability of good terrain data, for example from LiDAR, was limited. Today, 2D modelling is the most common approach in the United Kingdom for flood inundation modelling, and LiDAR coverage is extensive. The flood modelling process is also much more accessible with the availability of free and fully-featured modelling software, such as CH2M’s Flood Modeller Free and the Environment Agency’s free LiDAR.

Advances in flood modelling software and data have increased accuracy and reduced flood modelling costs. These advances have also made it much easier for non-modellers to become involved in the process of assessing current flood risk and analysing options to reduce future flood risk. The visualisation tools in modern software enable graphs, 2D mapping and 3D visualisations with animation to be easily produced, thus helping non-modellers better understand and evaluate the outputs. For instance, software tools make it easy to show predicted flow routes during a flood on animated maps, and communities can use these to help assess how realistic the predictions seem. Additionally, flood management options, such as new flood defences, can be drawn on maps within flood modelling software and new simulations can be undertaken quickly to assess the barriers’ effectiveness.

Getting communities more involved in the flood modelling process is beneficial

Insight from flood prone communities and their involvement in solution development can be critical for the success of flood risk management. However, the opportunity for greater stakeholder involvement in the modelling process and solution development is generally lost because flood modelling is still seen as a “back office” task. In general, the main stakeholder interaction still takes place at workshops, where the results of pre-calculated options are presented to communities. An inclusive, stakeholder-centric approach that involves the community in all stages of solution development is the best approach to take.

At the start of the process talk with the community to enable them to share their views of the local flooding characteristics, such as what floods first and what are the key influences on flooding. Also get their views on what are the potential flood management solutions – this will help guide the modelling approach as well enhance stakeholder involvement.

Once the initial version of the calibration model is developed, workshop the draft model with the community to bring in their soft knowledge. Work together to achieve a calibrated model such that all parties have a common understanding of how well it represents current conditions. When developing potential solutions, modellers can also host interactive workshops that allow communities to test different options and/or vary the dimensions of pre-defined options. The models that represent the potential solutions must include options that the community has suggested. For these sessions to be most effective, the modelling software needs to be sufficiently fast and robust to enable simulations to be undertaken during the sessions. Outputs need to include outline implementation costs, together with estimates of benefits achieved. Partnership funding calculations will also be needed to help stakeholders understand the level of local financial contribution that may be required for each of the options presented.

Engaging the community leads to success

Getting the community involved was an effective approach for CH2Mers working on the Oxford Flood Alleviation Scheme, where the lead modeller met with community groups and attended public meetings to capture local knowledge and gain support for the modelling that will underpin the scheme’s design. The local knowledge captured during these meetings helped the team identify important flood routes and build rapport with the community who entrusted them to work on the project.

Risk factors of engaging the community

Nevertheless, there are risks associated with encouraging increased stakeholder involvement in the modelling process, but the risks are likely to be outweighed by the potential benefits of identifying better solutions and gaining buy-in from the community.

To learn more about our approach to protecting communities from flood events, join Jon and other CH2M flood modelling experts for discussions and tips for using our industry leading Flood Modeller software at the 2016 Flood and Coast conference. Visit us at booth C10 and be sure to check out exciting opportunities to join our flood modelling team, on our careers page, here. To learn more about our involvement at the conference, follow our Twitter account.

Dr. Jon Wicks has more than 25 years of post-doctoral experience, including flood modelling of the Thames and Lower Mekong. A key part of Jon’s role is to work at the interface of flood modelling research, software development and customer requirements to ensure that innovative, efficient and effective tools are developed and used to improve the management of flood risk.