Flood Risk Management (Scotland) Act 2009 implementation: report to the Scottish Parliament - 2020

5. Scottish Water Progress

5.1 Background

Great progress has been made since the introduction of the Act in 2009 in understanding the impact of surface water flooding in Scotland, where our priorities lie and how we can work together to manage the impacts of floods on our communities. We now understand that approximately 210,000 homes, businesses and services are at risk from surface water flooding and that this is estimated to increase to 270,000 by 2080 through climate change.

5.2 Integrated Catchment Studies

Scottish Water is leading on a number of Integrated Catchment Studies in partnership with 20 local authorities across Scotland. These studies aim to create a detailed understanding of the above and below ground drainage systems – combined sewer networks, culverted and open watercourses and surface water sewers for example. They aim to understand the interactions of the drainage network and identify the sources and mechanisms of flooding in these urban areas. These studies were commissioned in two batches and are currently at varying stages of development.

In 2020, five of these studies have continued to progress through the Optioneering phase of work, which will identify the most sustainable solutions for managing flood risk in areas that have been identified as joint priority needs areas for Scottish Water and local authorities. Despite the impacts of the pandemic, the Optioneering phase of work remains on course to be completed during the first FRM cycle.

Ten studies have now completed the requirements of the actions within the current FRM strategies, with four of these completed in 2020. The final two studies have completed their model build and verification stages. These are currently undertaking a catchment flooding assessment which will identify the sources, mechanisms and impacts of flooding. These final studies will be completed in 2021. Dependent on the outcomes, some of these areas may continue to an Optioneering phase.

5.3 Section 16 Assessment of Flood Risk from the Sewer Systems

Scottish Water is progressing on schedule with the programme to undertake modelling to assess flood risk from the sewers systems across 201 catchments by the end of the first FRM cycle. As of December 2020, 198 assessments were complete. All other Section 16 assessments are on programme for completion within the first FRM cycle. On completion, the outputs are provided to SEPA for use in their National Flood Risk Assessment (NFRA2) and the continued development of their surface water (pluvial) mapping. The outputs are also provided to the appropriate local authorities as part of their SWMP Process.