From root: How can simulations help me take better actions?

How much flood risk can natural flood management offset?

Climate change is making UK flooding worse: how much can natural flood management interventions offset that risk, and is more spending always better?

The simulation below is calibrated to 16 years of Environment Agency data from the Upper Calder Valley, modelling how rainfall and catchment dynamics translate into peak river flows under different policies and climate scenarios.

Pick an NFM portfolio and a climate scenario, and watch how peak flows and intervention cost-effectiveness shift.

Catchment flood policy support: pick a portfolio of natural flood management interventions and a climate scenario; the simulator (calibrated to Environment Agency data from the Upper Calder Valley) shows peak flow distributions over a 25-member ensemble of 5-year stochastic runs. This is a research model fitted to surveillance data, not a flood-risk planning tool.

Simulation

 

 

Live controls
NFM portfolio
Climate scenario

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The link to this project can be found here.

Data and licence: This simulation is calibrated to river-flow and rainfall records from the Environment Agency Hydrology and Flood Monitoring APIs, with peak-flow data from the NRFA and climate projections from UKCP18. Environment Agency data contains public sector information licensed under the Open Government Licence v3.0.

References and further reading

Environment Agency. n.d.-a. “Hydrology Data Explorer.” Environment Agency. https://environment.data.gov.uk/hydrology/explore.
Environment Agency. n.d.-b. “Real-Time Flood Monitoring API Reference.” Environment Agency. https://environment.data.gov.uk/flood-monitoring/doc/reference.
Hall, Jim W., Paul B. Sayers, and Richard J. Dawson. 2005. “National-Scale Assessment of Current and Future Flood Risk in England and Wales.” Natural Hazards 36 (1–2): 147–64. https://doi.org/10.1007/s11069-004-4546-7.
Hardwick, Robert J. 2022. “Stochadex: A Simulation Engine Written in Go.” GitHub. https://stochadex.github.io/.
Hardwick, Robert J. 2026a. “floodrisk: Stochastic Simulations of Catchment-Scale Flood Dynamics.” GitHub. https://github.com/umbralcalc/floodrisk.
Hardwick, Robert J. 2026b. “How can simulations help me take better actions?” umbralcalculations, May. https://umbralcalc.github.io/posts/how_can_simulations_help_me_take_better_actions.html.
Hardwick, Robert J. 2026c. “How does a simulation learn its parameters from data?” umbralcalculations, November. https://umbralcalc.github.io/posts/how_does_a_simulation_learn_its_parameters_from_data.html.
Hardwick, Robert J. 2026d. “What is a state partition?” umbralcalculations, November. https://umbralcalc.github.io/posts/what_is_a_state_partition.html.
Jongman, Brenden, Philip J. Ward, and Jeroen C. J. H. Aerts. 2012. “Global Exposure to River and Coastal Flooding: Long Term Trends and Changes.” Global Environmental Change 22 (4): 823–35. https://doi.org/10.1016/j.gloenvcha.2012.07.004.
Merz, Bruno, Heidi Kreibich, Reimund Schwarze, and Annegret Thieken. 2010. “Review Article: Assessment of Economic Flood Damage.” Natural Hazards and Earth System Sciences 10 (8): 1697–724. https://doi.org/10.5194/nhess-10-1697-2010.
The National Archives. n.d. “Open Government Licence for Public Sector Information, Version 3.0.” The National Archives. https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/.