The Flood Hazard Maps and the Flood Risk Maps in the 3rd cycle

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The Polish Waters (PGW WP, Wody Polskie) is carrying out work related to the review and update of planning documents for flood risk management as part of the 3rd planning cycle (2022–2027) under the implementation of Directive 2007/60/EC of the European Parliament and of the Council of 23 October 2007 on the assessment and management of flood risks (the Floods Directive).

The review and update of flood hazard maps (FHM) and flood risk maps (FRM) in the 3rd planning cycle are funded by the European Funds for Infrastructure, Climate, and Environment 2021-2027.

In line with Article 171, paragraph 8 of the Water Law, flood hazard maps and flood risk maps must be reviewed every six years and updated if necessary.

The purpose of the maps review is to identify significant changes in flood hazard and risk and determine the scope of updates of the FHM and FRM as well as the required data.

During the review of FHM and FRM for river floods, the following factors are taken into account:

Results of the analysis of comments submitted to the maps during the 2nd planning cycle (letters from administrative authorities, internal comments from PGW WP, and others);
Results of the review of input data for flood hazard maps;
Results of the review of hydraulic models used to determine flood hazard areas;
Results of the review of input data for flood risk maps.

As part of the review of the flood hazard maps, the following activities are carried out:

Verification of data validity used in the hydraulic models.
An inventory of investments – finished since the previous FHM development and planned until 2025, focusing on those affecting the extent of flood hazard areas. The surveys is conducted among local government administrative bodies, Polish Waters units, maritime offices, GDDKiA (General Directorate for National Roads and Motorways), PKP (Polish State Railways), and road management authorities in regions with flood hazard areas. Information collected include data on the construction and modernization of water facilities, mobile flood protection systems, and road and rail engineering structures (e.g., bridges, culverts), as well as linear road and rail investments impacting floodwater flow conditions.
Analysis of hydraulic model construction and parameters as well as the review of hydrological and meteorological data.
Analysis of changes in topography and land cover, including digital terrain models, cross-sectional river data, and land cover data in floodplain areas.

In reviewing flood risk maps, verification of sources and identification of current data necessary for FRM updates is conducted (including data on the estimated number of inhabitants potentially affected by flooding, land-use classes, residential buildings) and analysis of data updates for calculating potential flood losses (including valuation adjustments).

After analyzing the factors and criteria under review and assigning them significance metrics for their impact on flood hazard and risk levels, a comprehensive evaluation of changes for individual river sections is made, based on which rivers or river sections are divided into two groups:

Indicated for update FHMs – in cases of significant changes identified in the comprehensive assessment;
Not indicated for update FHMs – in cases of minor changes or no impact on flood hazard levels.

For all river sections developed in the 1st and 2nd planning cycles (approximately 29400 km of rivers), updating of the flood risk maps is advisable due to changes in the input data determining the flood risk.