UK JBA Flood Maps

1. What is it?

The JBA Flood Mapping dataset provides comprehensive flood risk data, specifically designed to support underwriting decisions related to flood risk in the United Kingdom and Ireland. Using predictive modelling to assess the probability and impact of flood events, the allows insurers to understand and quantify risk levels for properties across various regions.

This dataset includes fields for both defended and undefended conditions. Key metrics cover flood depths and scores by flood type (river, coastal, surface water) across return periods like 1 in 20, 1 in 75, and up to 1 in 1000 years. Additional attributes provide risks related to canal failures, dam breaks, and drainage board statuses, alongside “floodability” and overall flood scores. This data assists insurers in precise property-level flood risk assessment.

Updated annually, JBA Flood Mapping is a valuable tool for the insurance sector, real estate, and property risk management.

2. How can I use it?

This dataset can be utilised by insurance underwriters and pricing experts to assess flood risks at the property level. By integrating JBA Flood Mapping data, insurers can identify high-risk areas, evaluate premium pricing, and tailor policies based on the specific flood exposure of individual properties. This is particularly beneficial for precise risk management and for providing detailed insights into different flood types (e.g., fluvial, pluvial, coastal flooding) impacting underwriting decisions.

3. How is the data created?

The data within JBA Flood Mapping is created using hydrodynamic modelling, incorporating a range of factors such as return periods (https://www.sciencedirect.com/topics/engineering/return-period) rainfall patterns, river flow, elevation, and historical flood records. JBA's proprietary models simulate potential flood scenarios, integrating local geography and climate data to produce accurate flood hazard assessments. This model undergoes periodic validation with observed data and is adjusted for annual updates to ensure reliability and relevance.

4. Are there any limitations?

While JBA Flood Mapping provides highly detailed flood data, there are some limitations:

• Annual Updates: The data is refreshed once a year, and only in targeted regions, so real-time flood risks or rapid environmental changes may not be immediately reflected.
• Data Granularity: Flood models are estimates and may not capture very localized or rare events with absolute precision.

5. What data points are available?

Defended Flood Risk (flddef)

This dataset provides flood risk data where flood defences are in place. Key fields cover river, coastal, and surface water flood depths and scores for various return periods, as well as defence standard ratings. Please refer to https://www.jbarisk.com/news-blogs/what-are-flood-defences/

• rmax20: Expected river flood depth for a 1 in 20-year event (in meters).
• rmax75: Expected river flood depth for a 1 in 75-year event (in meters).
• rmax100: Expected river flood depth for a 1 in 100-year event (in meters).
• rmax200: Expected river flood depth for a 1 in 200-year event (in meters).
• rmax1000: Expected river flood depth for a 1 in 1000-year event (in meters).
• sop_ri: Standard of protection for river defences, indicating the return period the defences are designed to withstand.
• level_ri: JBA confidence level in the defences. Using a score 1a, 1b, 2 or 3 Please refer to

• 

• fixt_ri: The type of river defences that are in place https://www.jbarisk.com/news-blogs/what-are-flood-defences/
• cdefmax75: Expected coastal flood depth for a 1 in 75-year event with defences (in meters).
• cdefmax100: Expected coastal flood depth for a 1 in 100-year event with defences (in meters).
• cdefmax200: Expected coastal flood depth for a 1 in 200-year event with defences (in meters).
• cdefmax1000: Expected coastal flood depth for a 1 in 1000-year event with defences (in meters).
• swmax75: Expected surface water flood depth for a 1 in 75-year event (in meters).
• swmax200: Expected surface water flood depth for a 1 in 200-year event (in meters).
• swmax1000: Expected surface water flood depth for a 1 in 1000-year event (in meters).
• sop_sw: Standard of protection for surface water defences, representing the return period the defences can handle.
• canal_failure: Boolean flag indicating if the property is at risk from canal failure.
• dam_break: Boolean flag indicating if the property is at risk from dam failure.
• idb: Boolean flag showing if the property falls within an area managed by an Internal Drainage Board (IDB).
• groundwater_chalk: Expected groundwater flood risk for areas with chalk aquifers, expressed as a return period.
• r20matrix: Flood risk score for a 1 in 20-year river flood event without defences (higher values indicate greater risk).
• r20matrix_def: Flood risk score for a 1 in 20-year river flood event with defences.
• r75matrix: Flood risk score for a 1 in 75-year river flood event without defences.
• r75matrix_def: Flood risk score for a 1 in 75-year river flood event with defences.
• r100matrix: Flood risk score for a 1 in 100-year river flood event without defences.
• r100matrix_def: Flood risk score for a 1 in 100-year river flood event with defences.
• r200matrix: Flood risk score for a 1 in 200-year river flood event without defences.
• r200matrix_def: Flood risk score for a 1 in 200-year river flood event with defences.
• r1000matrix: Flood risk score for a 1 in 1000-year river flood event without defences.
• r1000matrix_def: Flood risk score for a 1 in 1000-year river flood event with defences.
• river_floodscore_def: Overall flood risk score considering river defences.
• cdef75matrix: Flood risk score for a 1 in 75-year coastal flood event with defences.
• cdef100matrix: Flood risk score for a 1 in 100-year coastal flood event with defences.
• cdef200matrix: Flood risk score for a 1 in 200-year coastal flood event with defences.
• cdef1000matrix: Flood risk score for a 1 in 1000-year coastal flood event with defences.
• coastal_floodscore_def: Overall coastal flood score considering defences.
• sw75matrix: Flood risk score for a 1 in 75-year surface water flood event.
• sw75matrix_def: Flood risk score for a 1 in 75-year surface water flood event with defences.
• sw200matrix: Flood risk score for a 1 in 200-year surface water flood event.
• sw200matrix_def: Flood risk score for a 1 in 200-year surface water flood event with defences.
• sw1000matrix: Flood risk score for a 1 in 1000-year surface water flood event.
• sw1000matrix_def: Flood risk score for a 1 in 1000-year surface water flood event with defences.
• surfacewater_floodscore_def: Overall surface water flood score considering defences.
• groundwaterchalk_floodscore: Flood risk score for groundwater chalk flooding.
• floodscore_def: Aggregated flood risk score considering all defences.
• floodability: A textual classification that categorizes the general flood risk level of the property.

Undefended Flood Risk (fldudf)

This dataset provides flood risk data without the influence of defences. It includes depth and score metrics for river, coastal, and surface water flood events.

• rmax20: Expected river flood depth for a 1 in 20-year event (no defences).
• rmax75: Expected river flood depth for a 1 in 75-year event (no defences).
• rmax100: Expected river flood depth for a 1 in 100-year event (no defences).
• rmax200: Expected river flood depth for a 1 in 200-year event (no defences).
• rmax1000: Expected river flood depth for a 1 in 1000-year event (no defences).
• cudmax75: Expected coastal flood depth for a 1 in 75-year event (no defences).
• cudmax100: Expected coastal flood depth for a 1 in 100-year event (no defences).
• cudmax200: Expected coastal flood depth for a 1 in 200-year event (no defences).
• cudmax1000: Expected coastal flood depth for a 1 in 1000-year event (no defences).
• swmax75: Expected surface water flood depth for a 1 in 75-year event (no defences).
• swmax200: Expected surface water flood depth for a 1 in 200-year event (no defences).
• swmax1000: Expected surface water flood depth for a 1 in 1000-year event (no defences).
• r20matrix: Flood risk score for a 1 in 20-year river flood event.
• r75matrix: Flood risk score for a 1 in 75-year river flood event.
• r100matrix: Flood risk score for a 1 in 100-year river flood event.
• r200matrix: Flood risk score for a 1 in 200-year river flood event.
• r1000matrix: Flood risk score for a 1 in 1000-year river flood event.
• river_floodscore_ud: Overall river flood risk score (no defences).
• cud75matrix: Flood risk score for a 1 in 75-year coastal flood event.
• cud100matrix: Flood risk score for a 1 in 100-year coastal flood event.
• cud200matrix: Flood risk score for a 1 in 200-year coastal flood event.
• cud1000matrix: Flood risk score for a 1 in 1000-year coastal flood event.
• coastal_floodscore_ud: Overall coastal flood score (no defences).
• sw75matrix: Flood risk score for a 1 in 75-year surface water flood event.
• sw200matrix: Flood risk score for a 1 in 200-year surface water flood event.
• sw1000matrix: Flood risk score for a 1 in 1000-year surface water flood event.
• surfacewater_floodscore_ud: Overall surface water flood score (no defences).
• floodscore_ud: Aggregate flood risk score for all types (no defences).
• floodability: Textual description of flood susceptibility for the property.

Unflood (unflod)

This dataset provides information on areas with minimal or no flood risk, focusing on elevation as a primary factor. For further information please go to the JBA website https://www.jbarisk.com/news-blogs/representing-uncertainty-in-flood-maps/

• value: Unflood risk score from 1 (low) to 3 (high), reflecting the absence of flood risk.
• heightband: Elevation range in meters above sea level for the area, indicating the likelihood of flood risk based on topography.

Addresscloud Flood Risk Scores (acflod)

The Addresscloud Flood Risk Scores dataset provides percentile-based scores at address, building, land parcel, and postcode levels, considering defended flood scenarios.

• floodscore_def_adr_90pc: Defended flood risk score for an address at the 90th percentile within a 10-meter buffer.
• floodscore_def_adr_max: Maximum defended flood risk score within a 10-meter buffer around the address.
• floodscore_def_pco_max: Maximum defended flood risk score at the postcode level, summarizing risk across the area.
• surfacewater_floodscore_def_pco_max: Maximum defended surface water flood risk score at the postcode level, reflecting local surface water risk under defence scenarios.
• floodscore_def_bld_90pc: Defended flood risk score at the OS OML building level, at the 90th percentile.
• floodscore_def_bld_max: Maximum defended flood risk score at the OS OML building level.
• floodscore_def_bld_sit_max: Highest defended flood risk score within an INSPIRE land parcel at the OS OML building level.
• floodscore_def_sit_90pc: Defended flood risk score at the INSPIRE land parcel, at the 90th percentile.
• floodscore_def_sit_max: Maximum defended flood risk score for the INSPIRE land parcel.

These scores enable a multi-scale analysis of flood risk across varying levels of geography, supporting more precise risk assessments.

6. Where can I find out more?

For more detailed information about JBA Flood Data https://www.jbarisk.com/news-blogs/ you can explore the data sources listed above, our API documentation or contact our helpdesk using the chat option on this page.