Data comparison

Public flood maps vs an address-level risk model

The Czech insurers' flood map, the Slovak SVP hazard maps, the Polish ISOK maps and the JRC European maps each answer one specific question well, and each is free or near free at the point of use. An address-level model is not a replacement for them; it is built on them. This page sets out what each map answers, where it is enough on its own, and where it stops. Bytero sells an address-level model and says so.

Four public maps, four different questions

ČAP povodňové mapy, Czechia

How the Czech insurance market classes an address. Four tariff zones, TZ1 to TZ4, built and operated for the Czech Insurers' Association by Intermap. A pricing convention, not a hazard map you can read the depth from.

SVP hazard maps, Slovakia

Is the parcel inside a modeled river extent, and how deep. Floods Directive scenario lines for Q5, Q10, Q50, Q100 and Q1000 with depth and velocity attributes, published by the state water enterprise.

ISOK maps, Poland

Is the address in the 10 %, 1 % or 0.2 % annual-probability zone, or exposed if an embankment fails. Statutory maps prepared by Wody Polskie, with depth sheets and, for selected areas, velocity.

JRC river flood maps, Europe

How deep a large-river flood is on a 100 m grid, with one method from Portugal to the Black Sea. Nine return periods from 10 to 500 years, no local defenses, open license.

Map matrix

Map	Question answered	Resolution	Return periods	Pluvial	Depth	Defenses	Update cycle	Access
ČAP povodňové mapyCzech Insurers’ Association, operated by Intermap	which tariff zone (TZ1 to TZ4) the Czech insurance market puts an address in	per address; a Risk Asistent tool weighs elevation, distance to watercourses and terrain obstacles for individual properties	N-year river extents behind the zones; flash floods in four return periods	Yesflash-flood map folded into the tariff zone	Partial2D hydraulic modeling with velocity and duration behind the zones; depth grids not published	Yesstate flood-protection measures along about 9 000 km of watercourses as model inputs	generational rebuilds: RZ2023 built in 2022 and 2023; sixth-generation river maps announced for 2026	member insurers; paid property report for commercial purposes since 1 February 2023; the platform behind it is Intermap’s Aquarius RMA
SVP hazard mapsSlovenský vodohospodársky podnik, š. p.	whether a parcel lies inside a modeled Q5 to Q1000 river extent, and the depth and velocity there	vector flood lines per scenario with depth and velocity attributes	Q5, Q10, Q50, Q100, Q1000	Noriver scenarios only	Yesdepth in meters and velocity in meters per second, MIKE Flood	not published	six-year Floods Directive cycles	public web viewer by district; reuse license not stated on the portal pages
ISOK flood hazard mapsWody Polskie, Poland	whether an address is in the 10 %, 1 % or 0.2 % annual-probability zone, or exposed if an embankment fails	cartographic sheets and vector data per river reach	10 %, 1 % and 0.2 % annual probability (1-in-10, 1-in-100, 1-in-500 years)	Noriver, sea and hydrotechnical-structure floods	Yesdepth sheets; velocity and direction for selected areas	Partialseparate scenario for embankment destruction; 26 hydrotechnical structures mapped	six-year cycles; first cycle published 15 April 2015, second cycle 2016 to 2021	free public access: cartographic sheets at mapy.isok.gov.pl, vector data at wody.isok.gov.pl
JRC river flood hazard mapsEuropean Commission Joint Research Centre	how deep a large-river flood is at a given return period, comparably across Europe	100 m grid; river basins above 150 km²	nine return periods from 10 to 500 years	Noriver flooding only	Yeswater depth in meters per cell	Nolocal defenses, in particular dykes, are not accounted for	versioned releases; the current dataset was issued in March 2024	open download, CC BY 4.0
Bytero Shield(this site)address-level model, Alpue s. r. o.	what this building costs per year in expected flood loss, in money, next to what it is worth	building footprint and measured height at the address	those of the underlying state zones and JRC layers (JRC: 10 to 500 years)	YesHAND-style susceptibility everywhere; 2D pluvial model for part of the coverage	Partialfluvial depth from the JRC and EFAS layers on the state zones; not hydrodynamic simulation everywhere	Partialprotection-standard screening plus the state zones; no defense-failure simulation	follows the state and JRC sources as they update	API; markets: see /coverage

Every cell describes what the publisher states on its own pages. "Not published" means the publisher's pages do not say; it does not mean the map lacks it. The public maps are the legal and administrative record; a model is not, and nothing on this page changes that.

Where the public maps are enough

Use the public maps alone when

You are screening. Is this address inside any modeled river extent at all? The SVP lines, the ISOK zones and the JRC grid answer that for free, and for most of a portfolio the answer is no.
You are zoning a portfolio for accumulation control or reinsurance reporting, where a consistent zone label matters more than a depth. The Czech tariff zone is the market's shared label for exactly this.
The question is legal or administrative: whether a parcel is inside a statutory flood area, whether building is restricted, what the water authority has determined. Only the official map answers that, and a model that disagrees with it is wrong for that purpose.
You need cross-border comparability on the big rivers. The JRC maps apply one method at 100 m across Europe, which no national map does.
You need an insurer's likely reaction to a Czech address. The ČAP tariff zone is what member insurers use for risk assessment and premium calculation.

Where they stop

Pluvial flooding. The SVP scenario lines, the ISOK zones and the JRC grid are river maps. Only the Czech map carries a flash-flood layer, and it is folded into the tariff zone rather than published as a depth. Rain falling on a slope above a house that is nowhere near a river is invisible to three of the four.
Depth at the building. The ČAP zone hides the depth it was built from. The SVP and ISOK depths are attributes of a scenario polygon, not of a door threshold or a cellar. The JRC depth is a 100 m cell average.
Building elevation. None of the four knows how high the ground floor sits above the plot, whether there is a basement, or where the footprint lies inside the parcel. A plot inside a Q100 line can hold a house that stays dry.
Defended areas. The JRC maps state that they do not account for local flood defenses, in particular dyke systems. ISOK models embankment destruction as a separate scenario but not the reliability of the embankment. The SVP pages do not say. Behind a dyke, the public maps either over-state or under-state the risk depending on which map you read.
Update lag. The Floods Directive runs in six-year cycles. A flood, a new embankment or a new estate can be five years old before the map moves.
Money. No public map knows the value of the building or its rebuild cost, so none of them can turn a hazard into an expected annual loss.

What you should know about each

ČAP povodňové mapy

The Czech Insurers' Association is the expert guarantor of a map system that Intermap builds and operates. The current RZ2023 generation was built in 2022 and 2023 on a precise state terrain model with discharges from more than 200 gauging stations and 2D hydraulic modeling that produces velocity and duration as well as depth. In February 2026 the association announced a sixth generation of river maps and a second generation of flash-flood maps, commissioned by eight member insurers, with bridge profiles added as flow obstacles, 2D velocity modeling on about a hundred major watercourses, a terrain model of roughly 20 cm precision for the flash-flood component, and validation against anonymized claims from the September 2024 floods.

It answers the underwriting question and hides the engineering one. The tariff zone combines flood type, return period, depth and velocity into one label; the depth itself is not published. Member insurers use it for risk assessment and premium calculation, and a paid property report for commercial purposes has been offered since 1 February 2023.

SVP hazard maps

Slovenský vodohospodársky podnik prepares the flood hazard and flood risk maps required by Directive 2007/60/EC. The hazard maps are vector lines for five scenarios, Q5, Q10, Q50, Q100 and Q1000, each carrying water depth in meters and flow velocity in meters per second, produced with the MIKE Flood hydrodynamic model; the risk maps overlay exposed population, activities, installations and protected areas.

The best free depth in the region, and the narrowest in scope: river scenarios only, no pluvial layer, no API, a viewer rather than a download, and no reuse license stated on the portal pages. Whether and how defenses enter the model is not published.

ISOK flood hazard maps

Poland prepares statutory flood hazard maps (MZP) and flood risk maps (MRP) under Article 169 of the Water Law. They show areas of low probability at 0.2 % (once in 500 years), medium at 1 % (once in 100 years) and high at 10 % (once in 10 years), plus areas exposed at the 1 % flow if an embankment is destroyed; sea floods and floods from 26 hydrotechnical structures are mapped separately. The maps come in two thematic sets, one with water depth and one, for selected areas, with velocity and direction of flow.

The maps are free: cartographic PDF sheets at mapy.isok.gov.pl, vector data at wody.isok.gov.pl. They run in six-year cycles, with the first cycle published on 15 April 2015 and the second covering 2016 to 2021. Areas at 1 % and 10 % carry a statutory building ban, which makes the map a planning instrument as much as a hazard product.

JRC river flood hazard maps

The Joint Research Centre's maps cover Europe and the Mediterranean basin on a 100 m grid for nine return periods from 10 to 500 years, on river basins above 150 km², with each cell holding water depth in meters. They are produced with the LISFLOOD and LISFLOOD-FP models behind the European Flood Awareness System and released under CC BY 4.0; the current dataset was issued in March 2024.

The authors are explicit that the maps do not account for local flood defenses, in particular dyke systems, and that they are not an official flood hazard map. They resolve the Danube, the Elbe, the Morava and the Oder; they do not resolve the tributaries that cause most of the damage in a Central European flood.

Bytero Shield

One address in, valuation plus risk out. Fluvial from the state Floods Directive zones with JRC and EFAS depths layered on; pluvial from HAND-style terrain susceptibility with a 2D model for part of the coverage; defenses screened from protection standards and the state zones; loss expressed as an expected annual amount in money, per building, next to market value and rebuild cost from measured geometry.

It is not a hydrodynamic simulation everywhere, it has no legal standing, and on a state-modeled reach the state depth is the better number. Which markets are live is on the coverage page, and nowhere else on this site.

How an address-level model uses them

The public maps are inputs, not competitors

Bytero Shield treats the state Floods Directive zones as the fluvial baseline, because they are the record the regulator and the courts recognize, and lays modeled depths from the JRC river flood maps and the Copernicus EFAS layers over them. The pluvial layer is terrain susceptibility in the HAND style, built from the national terrain model, with a 2D pluvial model for part of the coverage; outside those areas it is a susceptibility index, not a depth. Defenses are screened from protection standards and from the state zones; there is no defense-failure simulation. The building's footprint, its measured height and its rebuild cost turn the hazard into an expected annual loss in money, and the same call returns the market value.

What the model adds is the join: one address, hazard and value together, on every address rather than only inside a mapped reach. What it does not add is a better river simulation than the state's own hydrodynamic study where one exists. On a reach the SVP has modeled with MIKE Flood, the SVP depth is the number to trust.

Where the public maps are the better answer

For a legal question, always. For a Czech insurer's pricing, the tariff zone. For a single building on a modeled reach, the state study's depth and velocity. For a cross-border view of the Danube, the Elbe or the Oder, the JRC grid. A model should be judged on how well it reproduces those maps where they exist and on what it adds where they do not: pluvial, elevation, defenses, money.

How this page is maintained

Every statement about a public map comes from the publisher's own pages or a public document, and each is re-checked on review. Zone thresholds and scenario lists change between map generations, so treat this as a reading guide rather than a specification. Corrections are welcome and will be applied.

Sources

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