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Flood Investigation Reports

Investigation reports relating to flooding in the Vale of Glamorgan


The Vale of Glamorgan Council, as a Lead Local Flood Authority (LLFA), has a duty to investigate and publish reports on flood events that occur within its area to the extent that it considers it necessary or appropriate.


On becoming aware of a flood in its area, a lead local flood authority must, to the extent that it considers it necessary or appropriate, investigate:

  • which risk management authorities have relevant flood risk management functions

  • whether each of those risk management authorities (RMAs) has exercised, or is proposing to exercise, those functions in response to the flood


Where an authority carries out an investigation, it must:

  • publish the results of its investigation

  • notify any relevant risk management authorities

 For further details, a copy of the full legislation is available here

Thresholds for Conducting Investigations

The thresholds for conducting formal Section 19 flood investigations, in general accordance with the indicators for significant harmful consequences as set out in the Local Flood and Water Management Strategy are:

  • an event where nine or more properties have been internally flooded

  • an event where two or more non-residential properties are internally flooded

  • an event where critical services are flooded or significantly disrupted


    an event where 750m of road (A Road, B Road, Local Street and motorway) or rail (any type) is directly impacted by flooding

  • an event where one or more nationally or internationally environmentally designated sites are detrimentally impacted by flooding

  • an event where one or more nationally or internationally important heritage features are detrimentally impacted by flooding

  • an event where an area greater than 0.4km2 of Grade 1, 2 or 3 land is flooded



Flood Investigation reports:


Section 19 reports
 DocumentEvent Date Date Published 
 Sully Section 19 report   23 - 24th December 2020   July 2021

Dinas Powys Section 19 Technical Report

Dinas Powys Section 19 Data Analysis

23 - 24th December 2020 November 2021

Lavernock Road Section 19 report

23 - 24th December 2020 May 2023

Sully Moors Road Section 19 report

29th Feb - 2nd Mar 2020 March 2023

Sully Moors Road Section 19 report

23 - 24th DEcember 2020 December 2023


Next Steps:


The Section 19 investigation for Sully has identified 18 properties that were affected by surface water flooding on 23rd December 2020.  The Vale of Glamorgan has already secured £149,270 funding to provide property level flood protection measures to 21 properties in Sully.  Property surveys are ongoing and installation is planned within the next 6 months.  Whilst this will help protect the individual properties it won’t help prevent any wider impacts due to flooding of gardens, outbuildings and roads.  The Lead Local Flood Authority therefore intends to assess the viability of a community level scheme to manage the risk of surface water flooding in the area, starting with an application to Welsh Government for funding to develop an outline business case.  Development of an outline business case will require more detailed modelling of the existing flood risk and potential damages as well as the assessment of options, such as flood storage areas or upgrading of existing infrastructure and associated costs.  The timescales for delivery of any physical works will depend on the location and type of works as well as securing the necessary funding and consents for delivery.  Subject to a successful bid to Welsh Government for Flood Defence Grant in Aid, preparation of an outline business case is expected to commence in April 2022, with an estimated completion timescale of 6 months.  



A Section 19 investigation for Dinas Powys identified 98 properties that were affected by internal flooding on 23rd December 2020 and one of the key recommendations was to consider the viability of Property Flood Resilience (PFR) measures for at risk properties across Dinas Powys.  Since the 2020 event the Vale of Glamorgan has developed a business case and secured Welsh Government grant in aid funding allocation of £2.5M for the installation of PFR to 181 properties.  Procurement of the PFR installation contract is ongoing with award anticipated in April 2023, subject to Welsh Government funding approval, and an estimated 9 month programme of works.