Scoping review: factors contributing to surface water flooding

A review of Section 19 investigations to help practitioners identify the factors that contribute to surface water flooding and limitations in procedures.

From:
Flood and Coastal Erosion Risk Management Research and Development Programme and Department for Environment, Food & Rural Affairs
Published
23 February 2021
Category:
Managing flood incidents
Topics:
Asset performance, Flood risk assessment, Incident management, Resilience planning, Resilient infrastructure, Spatial planning, Strategy and planning, Sustainable drainage systems
Project status:
Completed
Project code:
FD2692
Date of completion:
31 March 2015

Documents

Section 19 LLFA reports: evidence review of factors contributing to surface water flooding - final report (1 MB) PDF

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Details

Background

Many factors contribute to surface water flooding, including the:

  • capacity of drains and sewerage
  • higher than expected rainfall
  • failure to make accurate assessments of runoff
  • absence of information about the impact of new development
  • inadequate maintenance of sustainable urban drainage systems (SuDS)

Objectives

The aim of the Section 19 investigations (under the Flood and Water Management Act 2010) is to explain a flood event and define the responsibility of the various authorities during the event. The recommendations help the authorities to learn from the event and address the infrastructure needs associated with it.

Section 19 investigations were reviewed along with other relevant information, such as academic literature and water company reports. This was to identify the factors that contributed to surface water flooding, and how common they are. Reviewing reports on floods and their causes makes drainage practitioners aware of the limitations of existing procedures.

Conclusions

A number of conclusions can be drawn from the review of Section 19 investigations:

  • the threshold for Section 19 reports varies between authorities, but most authorities state what threshold they apply
  • having a threshold that can be amended allows flexibility for the Lead Local Flood Authorities (LLFAs) to adapt their measures
  • Section 19 reports range from one page to over 100 pages, however the most effective reports tend to be around 25 pages long - they’re concise and focus on reporting the:
    • specific event
    • hydrological aspects
    • performance of drainage systems
    • causes of flooding

This project was run during 2015 at a cost of £36,418.

Published 23 February 2021