United Kingdom

	Inland Flood
	Storm Surge
	Europe Windstorm

U.K. Inland Flood

Inland flooding is a principal cause of catastrophic loss in the United Kingdom. Several major flooding events have struck over the past ten years, culminating in the devastating summer 2007 floods, which are estimated to have caused around £3billion of insured losses. Losses from flood events can accumulate significantly, and U.K. flood risk continues to increase due to accelerated development in river floodplains. 

Based on several years of extensive research since the original model release in 2001, the 2008 update of the fully probabilistic RMS® U.K. Inland Flood Model incorporates the latest generation of flood modeling at RMS to provide the high-resolution capability necessary to price and underwrite policies and manage portfolio accumulations. The model employs new numerical modeling approaches to cover all sources of flood risk on and off the major floodplains, by physically modeling major rivers as well as flooding from the vast network of minor rivers and temporary streams, surface water flow, the impacts of rising groundwater levels, and drainage overflow in urban areas. Around 1 million kilometers (over 600,000 miles) of river and surface water flow are physically modeled on the latest digital terrain model of 10m resolution, resulting in highly realistic flow modeling and flood footprints.

The RMS model calculations are performed on a propriety RMS variable resolution grid (VRG) of up to 50-meter resolution allowing high-level differentiation of flood risk. Damage functions relate the level of insurance loss to the depth of floodwaters using a component-based approach derived from engineering and flood studies, and several years of flood survey experience, and collecting claims and damage information after the major events of 1998, 2000 and 2007. Damage can be differentiated by 12 risk modifiers including the ability to assess losses by individual floors.  If detailed risk information is lacking, the model falls back on a detailed building inventory which captures regional variations in building characteristics and applies the most appropriate damage function dependent on the risk location. 

Accessing information about flood risk is available as a suite of products comprising return period flood maps and flood risk rating tools to probabilistic loss models in RiskLink® DLM and ALM. Each product is tailored to meet the differing needs of business segments to improve and ensure alignment of underwriting and portfolio management decisions.

Model Highlights

	Comprehensive high-resolution assessment of precipitation-driven flood risk across the whole of the British Isles from both river flooding and surface water flooding
	Rainfall simulation methodology reflects temporal-spatial reality of rain across the U.K. and Europe
	Continuous rainfall-runoff simulation methodology captures the importance of antecedant conditions and how these can drive the extent and severity of flooding from subsequent rainfall events
	Comprehensive research into climate change impacts on rainfall and stream flow patterns across the U.K.
	Model developed on an enhanced country-wide 10 m horizontal resolution digital terrain model
	Detailed river flood defense information incorporated into the model for inundation and downstream river flows calculations
	All components of the model rigorously validated against rainfall, stream flow, and loss data
	Calculations performed on a variable resolution grid (VRG) of up to 50-meter horizontal resolution
	U.K.-specific vulnerability functions calibrated from engineering studies and loss data from recent events
	Detailed inventory data defined at postcode sector for unknown construction, occupancy or height

Geographic Scope

U.K., excluding Northern Ireland, the Channel Islands, and the Isle of Man

Exposure Data Resolution

Inland flood risk can be analyzed at latitude/longitude, street address, postcode unit, postcode sector, CRESTA Zone

U.K. Storm Surge

The size and shape of the North Sea basin, wide areas of forcing winds, and extensive regions of low-lying coastal land combine to make Europe’s North Sea coastline particularly susceptible to storm surge flooding events driven by winter storms. The RMS® U.K. Storm Surge Model allows companies to evaluate coastal flood risk along the most vulnerable East Coast of England, from the Humber to the Thames Estuary.

Model Highlights

	Over 1,000 stochastic storm surge events along the U.K. East Coast with associated windfields and their probabilities
	Different tidal states capture the interaction of the tide with the storm surge.
	Sea defense failure modeling of even the strongest defenses, including the Barking, Dartford Creek, and Thames barriers.
	Time-stepping inundation model that accounts both for seawater volume and the duration of high water levels along the coast.
	Flood depths calculated using at up to 50-meter resolution to model storm surge flood risk in densely populated coastal areas
	Component-based vulnerability module that incorporates the storm surge damage to each element of a building  as basements or flood protection that may mitigate or augment the losses

Geographic Scope

The United Kingdom's East Coast, from the Humber estuary to the Thames

Exposure Data Resolution

Storm surge risk can be analyzed at latitude/longitude, street address, Postcode district, Postcode sector, or CRESTA zone