3 September 2012
A two-dimensional flood inundation model has helped advance the predictive tools used to generate national flood maps, assess flood risk for the global insurance and re-insurance industry and estimate flood damage.
The power of LISFLOOD-FP lies in its relative simplicity. Prior to its development, the prevailing wisdom was that better predictive models resulted from using increasingly complex physics equations that in turn required expensive computer power to solve. Hydraulic modellers found that the more physics they put into their models, the closer they came to predicting observations in controlled laboratory experiments, and so they continued to build more physics into the models.
In the 1990s, Paul Bates, Director of the Cabot Institute and Professor of Hydrology at Bristol, decided to re-think the physics behind the models. He joined his friend Dr. Ad de Roo of the EU Joint Research Centre in Italy and for three months the colleagues worked to develop a new flood inundation code.
“Instead of looking at including more and more complex physical processes, we turned that modelling paradigm on its head and asked ‘what’s the simplest model that matches the available data and still allows us to predict what we want’,” said Bates. “We found that the way to improve the predictive skill of the model was not to load more physics in, but to work out what was the minimum physics required to simulate the processes of interest that then allows the model to run on the finest grid possible over the biggest area.”
Bates had no idea that this discovery would lead to more than a decade of research. Since the 1990s, he and his colleagues have moved the LISFLOOD-FP model forward and with each step they have openly published their advancements, building a blueprint for both academic and commercial code developers and saving industry years of developer time.
“Our original 2D floodplain model, JFlow, was closely related to the LISFLOOD-FP model,” said Dr. Rob Lamb, Chief Scientist at the engineering consultancy and risk management company JBA Group. “The LISFLOOD-FP research established a proof of concept for the robust use of relatively simple hydraulic concepts to model flows dynamically on a digital terrain model grid.”
Clones of LISFLOOD–FP have been used by high-impact engineering and risk management consultancies such as JBA Group to produce the national flood map for the UK’s Environment Agency showing the predicted 1 in 1000 year flood outline, RMS Ltd to conduct risk analysis for the global insurance and re-insurance industries, and Ambiental for generating flood mapping tools used by the international insurance industry
LISFLOOD-FP has also been used directly by the specialist environmental consultancy Haycock Associates when consulting with multi-stakeholder groups. They animate the model output to create an effective communication tool for discussing flood risk and management strategies.
“An example of this was the flood in August 2004 at Boscastle where the dynamics of the flood wave was perceived differently between different stakeholder groups,” said Dr. Nick Haycock, Director of Consulting for Haycock Associates. “The modelling and animation enabled the community to concentrate on the mitigation solutions and linkage of catchment engineering and channel engineering through the village.”
Bates has also made a shareware version of the model available on the University of Bristol website. In just over a year, there have been 104 unique downloads from 34 different countries with a diversity of applications. It’s being used by scientists in China to help estimate the impacts of sea level rise on coastal zones; an area with high agricultural importance and a population of tens of millions, including some of the most populous cities in China such as Shanghai and Guangzhou.